Abstract # 1065: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
OUTLOOK ON AEROPONIC CULTURES IN IRAN

Afzalipour, M¹, Kafi, M¹, Babalar, M¹ and Fattahi Moghadam, M¹

¹Department of Horticulture, Faculty of Agriculture, University of Tehran, Karaj, Iran
Email: mafzalipour@yahoo.com

Aeroponics is a method of soilless culture in which roots are suspended within a closed chamber and receive an intermittent or constant application of sprayed nutrient solution. The major advantage of the aeroponics system is the control of cultural conditions. Aeroponics promotes good ventilation and stimulates extension of root hairs.

We have developed a new aeroponic system that uses compressed ambient air to atomise nutrient solution, which was sprayed onto the roots of Gerbera jamesonii "Double Dutch". The interval times were either three minutes spraying - fifteen minutes off or three minutes spraying - thirty minutes off.

The three minutes spraying - fifteen minutes off treatment promoted plant growth and production of flowers, with 90% of the plants in this treatment producing flowers compared with only 40% of the plants in the thirty minutes off treatment. The treatment of three minutes spraying - thirty minutes off promoted vegetative growth, with these plants producing nearly 20% more leaves than the fifteen minutes off treatment (9.5 leaves per plant vs 8 leaves per plant). These results were recorded 2 months after cultivation commenced and the trial is ongoing.

It seems that this system is very useful in countries such as Iran due to reduced water usage and loss, but further investigations are needed to determine the best approach for optimal flower production.

CALATAYUD, A., GORBE, E., ROCA, D. & MARTÍNEZ, P.F., 2008. Effect of two nutrient solution temperatures on nitrate uptake, nitrate reductase activity, NH₄⁺ concentration and chlorophyll a fluorescence in rose plants. Environ. Exp. Bot. 64, 65-74.

SRIHAJONG, N., RUAMRUNGSRI, S., TERDTOON, P., KAMONPET, P. & OHYAMA, T., 2005. Heat pipe as a cooling mechanism in an aeroponic system. Appl. Therm. Eng. 26, 267–276.

The authors would like to thank M. Khanjari for providing the gerbera seedlings.

Keywords: Aeroponic, Gerbera, Spray ,

Abstract # 1123: A Paper on Crop nutrition & water / Gewasvoeding & water
PREDICTING N-MINERALIZATION IN SOIL OF THE WESTERN CAPE WHEAT PRODUCING AREA.

Agenbag, GA¹

¹Department of Agronomy Private bag X1 Matieland 7602
Email: gaa@sun.ac.za

Worldwide, nitrogen is next to moisture, regarded as the most important yield limiting factor in crop production. Nitrogen fertilization is, however, expensive and may attribute as much as 30% of the total variable production cost of winter cereals in the Western Cape winter cereal producing areas. During the last number of years, crop rotation systems which include legumes and conservation tillage with no till planting became very popular in these areas. This may result in improved soil fertility levels and higher N-mineralisation potentials. Under these conditions, presently used N fertilization programs which do not make use of soil N measurements may not be accurate any more.  

Soil samples were collected from different localities in both the Swartland and Southern Cape wheat producing areas. After analysing these soil samples to determine their physical and chemical properties they were subjected to a series of incubation experiments at different temperature and soil water levels to measure the N-mineralization potential. Multiple regression analysis was done on the data and a prediction model was developed, using the N-balance approach.

The model showed that N-mineralization during the first 40 days after planting, when most of the yield potential of spring wheat cultivars is established, can be predicted by using the soil pH, clay content, organic C, total N and C:N ratio. Residual N at planting, however, can not be predicted by the model and needs to be measured. In this model, long term climatic data is used to accommodate different planting dates while yield records are used to determine the total nitrogen needs. 

The model seem to be quite accurate when used in the Swartland area where very little rain occurs during the summer and wheat is planted after the first rains in autumn, but seem to be less accurate in the Southern Cape where as much as 40% of the total annual rainfall is received during summer. In order to improve the model for field use, more research is needed to determine the percentage recovery of applied nitrogen in different soils and rainfall conditions.      

Keywords: N-mineralization ,

Abstract # 1209: A Paper on Crop production / Gewasverbouing
SCREENING OF SOME MAIZE CULTIVARS FOR ACETOCHLOR TOLERANCE

Alleman, J¹ and Mphundi, PM¹

¹University of the Free State, PO Box 339, Bloemfontein 9300
Email: allemannj@ufs.ac.za

Keywords: Acetochlor, corn, cultivar, maize, phytotoxicity, tolerance

Abstract # 1130: A Paper on Crop nutrition & water / Gewasvoeding & water
PRUDENT USE OF MUNICIPAL SLUDGE FOR AGRICULTURAL PRODUCTION

Annandale, JG¹, Tesfamariam, EH¹, Steyn, JM¹ and Stirzaker, RJ²

¹University of Pretoria, Department of Plant Production and Soil Science, Pretoria; ²CSIRO Land and Water, P.O.Box 1666, Canberra, Australia, 2061and CRC for Irrigation Futures
Email: John.Annandale@up.ac.za

Agricultural use of sludge is expected to increase due to its agricultural benefits and possible economic advantages. The current South African sludge guideline is considered prudent, and allows an upper limit of 10 t ha^-1 yr^-1. However, a dynamic decision support system would be useful to responsibly utilize sludges as valuable nutrient (N and P) sources in agriculture. The overall objective of this study was to investigate the dynamic nature of sludge loading and asses the environmental impacts associated with N based sludge application through nitrate leaching and soil profile P build up. 

Nutrient balances of four cropping systems, dryland maize, an irrigated maize/oat rotation, dryland pasture (Eragrostis curvula), and turfgrass, were investigated on a clay loam soil, at ERWAT, Ekurhuleni district apart from an inorganic fertilizer control treatment. The first three cropping systems were treated with four sludge rates of 0, 4, 8, and 16 t ha^-1 yr^-1. The fourth cropping system was treated with five sludge rates of 0, 8, 33, 67, and 100 t ha^-1 yr^-1. The sludge used in this study was anaerobically digested and paddy-dried having the quality that allows it to be utilized in agriculture. Field results were used to validate a nutrient (N & P) version of the Soil Water Balance (SWB) model developed as a decision support tool for site specific sludge loading recommendations.

Mean forage N uptake by the irrigated maize/oat rotation was equivalent to the N supply from 22 t ha^-1 yr^-1 sludge, while the dryland maize was only able to utilize an N equivalent of 6 t ha^-1 yr^-1 sludge. The turfgrass on the other hand, was able to export as much as 33 t ha^-1 sludge per harvest, without reducing turf growth and quality. Nitrate concentration of soil solutions collected from 0.3 m deep wetting front detectors in the 16 t ha^-1 irrigated maize/oat rotation and the 33 t ha^-1 turfgrass treatment, were below drinking water standards. However, soil P accumulation was evident in all agronomic cropping systems. The N model was successfully calibrated and validated with acceptable accuracy for dryland maize and an irrigated maize/oat rotation. The model was also successfully calibrated for dryland pasture. Model accuracy, however, was low during corroboration due to the non-mechanistic approach followed by the model when simulating the growth of perennial grasses. 

Sludge loading to satisfy crop N demand is dynamic, as it depends on sludge N content and cropping intensity. Ultimately, maximum cumulative municipal sludge loading to an area will depend on the accumulation of P and heavy metals and the risk this poses for pollution. The model developed is a useful decision support tool for sustainable sludge use in agricultural lands. 

Funding from WRC, ERWAT, and SASOL is gratefully acknowledged

Keywords: sludge, nutrient balances, cropping systems, leaching, SWB, modelling

Abstract # 1076: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
DETERMINATION OF THE OPTIMAL TIME FOR SHOOT TIP MICROGRAFTING OF WALNUT

Balanian, H¹ and Fattahi Moghadam, M¹

¹Department of Horticulture, Faculty of Agriculture, University of Tehran, Karaj, Iran
Email: balanian@ut.ac.ir

Keywords: micrografting, walnut

Abstract # 1161: A Poster on Soil fertility / Grondvrugbaarheid
ASSESSMENT OF VARIABLE APPLICATION RATES OF BIOLOGICAL AMENDMENT SUBSTANCES ON SEEDLING ESTABLISHMENT AND GROWTH CHARACTERISTICS OF MAIZE GROWN UNDER GLASSHOUSE CONDITION

Baloyi, TC¹, Kutu, FR² and Du Preez, CC³

¹ARC-Grain Crops Institute, P/Bag X1251, Potchefstroom 2520; ²School of Agriculture and Environmental Sciences, University of Limpopo, Private Bag X1106, Sovenga 0727; ³Department of Soil, Crop and Climate Sciences, University of the Free State P.O. Box 339, Bloemfontein 9300
Email: baloyitc@arc.agric.za

Keywords: Industrial manufactured biological amendment substances, maize phenology, seedling emergence, soil amendments

Abstract # 1068: A Paper on Crop quality / Gewaskwaliteit
IS LATE MATURITY α-AMYLASE A REALITY IN SOUTH AFRICA?

Barnard, A¹

¹ARC-Small Grain Institute, Private Bag X29, Bethlehem, 9700
Email: barnarda@arc.agric.za

Late maturity α-amylase (LMA) is a genetic defect present in some genotypes that can result in high levels of α-amylase and low falling numbers (FNs) in ripe grain in the absence of preharvest sprouting (PHS) or rain. During recent years high levels of low FNs in wheat was experienced in parts of South Africa, especially in the summer rainfall area of the Free State and Mpumalanga. A lot of wheat has been downgraded at intake level due to low FNs, but without any visible sprouting damage. Was this due to LMA expression?  Research was conducted to determine if LMA is a reality in South African wheat cultivars.

During 2007 and 2008 trials were planted according to a randomised complete block design with four replicates under a rain shelter to prevent rain on the physiologically ripe ears.  Trial plots consisted of five rows of 2 m length each and an inter-row spacing of 45 cm.  Nine South African wheat cultivars, varying in PHS resistance, as well as four international standards, of which the LMA status is known, were included in the trials.  The induction of LMA was done by removing tillers 25 – 30 days post anthesis, and placed in water in a controlled environment growth room at lower temperatures (13-18°C). After 7 days in the cool environment, the detached tillers were transferred to a similar growth room at higher temperatures (16-30°C) until maturity (Mares & Mrva, 2008). In order to determine the effect of cool temperatures on PHS, ears that received the cool treatment, as well as the control ears that remained in the field and ripened under normal growing conditions, were subjected to simulated rainfall.  FNs, as well as the direct measurement of α-amylase through the Phadebas method, were also determined on both cool treatment ears and control ears.

The PHS scores of certain cultivars were significantly (P<0.05) lower after being subjected to a cool treatment than the controls, indicating a higher PHS resistance under these conditions. Falling numbers in certain cultivars were significantly (P<0.05) lower after a cool treatment, indicating a higher α-amylase activity which was confirmed by direct α-amylase measuring. Results indicated that PHS and LMA are not correlated.

In five of the cultivars tested LMA was expressed after a cool treatment. The direct measurement of α-amylase indicated that Elands was the only cultivar with a low enzyme activity after exposure to simulated rainfall. It is clear that, even if Elands is prone to LMA and can sometimes produce low FNs, the PHS resistance of this cultivar is exceptional. From the results it is clear that LMA is indeed a reality in certain South African wheat cultivars and it should be addressed in future research.

Mares, D. & Mrva, K., 2008. Late maturity α-amylase: Low falling numbers in wheat in the absence of preharvest sprouting. J. Cer. Sci. 47(1), 6-17.

Keywords: late maturity amylase, preharvest sprouting, wheat ,

Abstract # 1180: A Poster on Crop protection / Gewasbeskerming
COMPARING METHODS FOR MEASURING THE PATHOGENICITY AND TOXICITY OF FUSARIUM VERTICILLIOIDES IN MAIZE

Belgrove, A¹, Flett, BC¹ and Viljoen, A²

¹Agricultural Research Council-Grain Crop Institute, Private Bag X1251, Potchefstroom 2520, South Africa; ²Department of Plant Pathology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
Email: BelgroveA@arc.agric.za

Fusarium verticillioides is a fungal plant pathogen known to cause Fusarium ear rot of maize and, more significantly, to produce toxic secondary metabolites called fumonisins in maize kernels. Fumonisins are categorized as class 2B carcinogens and are associated with mycotoxicoses in various animals. The toxin has also been linked to oesophageal cancer incidence in humans. The aim of this study was to evaluate in planta inoculation methods to distinguish isolates of F. verticillioides that are able to cause visual symptoms from those unable to cause symptoms, but still produce fumonisins in maize.

Three cultivars and four F. verticillioides isolates were used for pathogenicity trials in growth cabinets and the field. Two inoculation techniques were compared in a plant growth cabinet. For the first technique, maize seed was inoculated by flooding maize kernels with a spore solution prior to planting. The second technique involves planting of maize seed in sand inoculated with F. verticillioides grown on autoclaved millet seed at an inoculum density of 3%. After two weeks root and shoot length and weight was determined. Two techniques were also used for field inoculation, viz. 1) silk inoculations and 2) toothpick inoculations. Silk inoculations involve injecting the maize ear with a spore suspension of each isolate and toothpick inoculation entails inoculating ears with an infested toothpick. The trial was planted in a randomised block design with four replicates. Disease severity was rated using percentage ear area infected at harvest. Maize grain samples were further collected and analysed for levels of fumonisin contamination using enzyme-linked immuno sorbent assay (ELISA) kits.

Growth chamber data correlated poorly to results obtained in the field. The results obtained in both trials were not significant (p < 0.05), thus suggesting that none of the methods tested were able to distinguish between the pathogenicity of the isolates. The occurrence of disease symptoms did not compare well with fumonisin levels. Although direct inoculation of the ear occurred, disease severity remained low but ELISA tests showed fumonisin levels to be higher than 2 ppm (FDA and EU recommended limits).

Growth chamber and field tests for rapid identification of pathogenicity were arduous and time consuming. Further studies to refine a rapid, accurate screening test are underway.

We thank the Maize Trust and The Agricultural Research Council for financial support.

Keywords: ELISA, Fumonisin, Fusarium verticillioides, pathogenicity

Abstract # 1206: A Paper on Keynote speech
ADVANCES IN SOIL AND WATER MANAGEMENT FOR SUSTAINABLE CROP PRODUCTION IN SOUTHERN AFRICA

Bennie, ATP¹

¹Part-time Professor, University of the Free State, PO Box 339, Bloemfontein 9300
Email: bennieboer@nashuaisp.co.za

Keywords: soil classification, fallowing, drought risk ,

Abstract # 1127: A Paper on Hort physiology / Tuinboufisiologie
CARBOHYDRATE PATTERNS PRESENT DURING THE ONTOGENETIC DEVELOPMENT OF ‘HASS’ AVOCADO

Bertling, I¹, Tesfay, SZ¹ and Bower, JP¹

¹Horticultural Science, School of Agricultural Sciences and Agribusiness,University of KwaZulu-Natal, P Bag X01, 3209, Scottsville, Pietermaritzburg, South Africa
Email: BertlingI@ukzn.ac.za

Avocado (Persea americana Mill.) is one of very few plant species able to synthesize and translocate significant amounts of heptose sugars. The heptoses D-mannoheptulose, and its polyol form, perseitol, are found in all tissues/organs and during various phenological stages of avocado development (Liu et al., 1999). These heptoses, as well as starch, are recognized forms of carbohydrate reserves in avocado (Bertling & Bower, 2005). An ontogenetic approach was used to elucidate the role of various sugars present in ‘Hass’ avocado, in an attempt to understand carbohydrate partitioning, transport and storage in avocado.

Fruit were collected from an orchard located in the KwaZulu-Natal Midlands, South Africa. Monthly sampling of 20 fruit at characteristic stages (from early fruit set to commercial fruit maturity) was carried out as well as sampling from seedlings grown under controlled environment conditions, either with or without light. At specific ontogenetic stages plants were either destructively harvested or leaf and fruit material was removed from mature trees. Sugars were analyzed using HPLC. Statistical analyses were performed using GenStat, 11^th edition.

The embryo of the mature seed contained hexoses and heptoses during seed germination, while ontogenetically mature tissue contained mainly heptoses. Hexoses and heptoses were produced in different amounts at the examined phenological stages. The shoots of etiolated seedlings contained significantly higher concentrations of perseitol, glucose, fructose and mannoheptulose than seedlings grown under light. However, the starch concentration of etiolated seedlings was lower than that of light-exposed ones.

The dominance of heptoses during early ontogenetic stages compared to that during the later stages seems to be a typical feature of the ontogenetic development of ‘Hass’ avocado.

BERTLING, I. & BOWER, J.P., 2005. Sugars as energy sources – is there a link to avocado fruit quality? S. Afri. Avocado Growers’ Assoc. Yrbk. 28, 24-27.

LIU, X., ROBINSON, P.W., MADORE, M.A., WITNEY, G.W., & ARPAIA, M.L. 1999. ‘Hass’ Avocado Carbohydrate Fluctuations. II. Fruit Growth and Ripening. J. Am. Soc. Hortic. Sci. 124, 676–681.

Keywords: D-mannoheptulose , Perseitol

Abstract # 1086: A Paper on Hort physiology / Tuinboufisiologie
HIGH TEMPERATURE EFFECTS ON VEGETATIVE AND REPRODUCTIVE PHYSIOLOGY OF PROTEA CV. PINK ICE

Bezuidenhout, E¹, Hoffman, EW¹ and Midgley, SJE²

¹Dept Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland 7602, South Africa; ²OneWorld Sustainable Investments, PO Box 8359, Roggebaai 8012, South Africa
Email: 14085399@sun.ac.za

Keywords: ecophysioloy, global warming, Protea ,

Abstract # 1103: A Poster on Crop quality / Gewaskwaliteit
EVALUATION OF THE SUITABILITY OF CACTUS PEAR FRUITS FOR JELLY MAKING

Bothma, C¹, Frey, M¹, De Wit, M¹ and Hugo, A¹

¹PO Box 339, University of the Free State, Bloemfontein 9300
Email: bothmac.sci@ufs.ac.za

Keywords: sensory analysis, cactus pear, jelly, texture

Abstract # 1204: A Paper on Crop production / Gewasverbouing
MECHANIZATION OF THE IN-FIELD RAINWATER HARVESTING TECHNIQUE: A CASE STUDY AT PARADYS EXPERIMENTAL FARM

Bothma, CB¹, Van Rensburg, LD² and Le Roux, PAL²

¹GWK Bpk. Douglas, Posbus 47, Douglas 8730; ²Soil Science (54), UFS, PO Box 339, Bloemfontein 9300
Email: ibothma@gwk.co.za

Keywords: Mechanization, IRWH , ridge plough, puddle plough

Abstract # 1176: A Paper on Soil physics / Grondfisika
HYDRAULIC PROPERTIES OF A HUTTON SOIL PROFILE IN THE SOUTH-WESTERN FREE STATE

Bouwer, D¹, Van Rensburg, LD¹, Hensley, M¹ and Le Roux, PAL¹

¹University of the Free State, PO Box 339, Bloemfontein 9300
Email: bouwerd@ufs.ac.za

INTRODUCTION

Keywords: Ksat, Double ring infiltrometer, ECH2O soil water sensor, K-Ө relationship, Soil- water potential,

Abstract # 1153: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
EFFECT OF LIGHT AND PACKAGING ON SHELF LIFE OF FRESH-CUT SWEET BASIL AND ROSEMARY

Bower, J¹, Bertling, I and Anderson, R

¹Horticultural Science, University of KwaZulu-Natal, Pietermaritzburg, P/Bag X01, Scottsville, 3209
Email: bowerj@ukzn.ac.za

The sale of fresh-cut herbs is often adversely affected by poor storage life. Temperature and humidity levels are known, but not concentrations of gases in the packaging. Light is believed to delay chlorophyll breakdown and thus senescence (Lopresti and Tomkins, 1997). The correct levels of gasses such as CO₂ and O₂ are difficult to apply and maintain, and with relative humidity, can be influenced by packaging. The objective was to investigate different forms of packaging, storage conditions and atmosphere for packaged herbs.

Rosemary and sweet basil were used. Micro-perforated packaging (Thompson,1998), was tested against non-perforated polypropylene bags, with normal and modified atmospheres applied to the non-perforated bags. Rosemary was stored at 1⁰C for 21 days and basil for 9 days at 12⁰C, with and without light.

In the non micro-perforated bags, carbon dioxide levels increased rapidly and caused deterioration. While a modified atmosphere may be advantageous (Thompson, 1998; Amodio et al., 2005), concentrations are important, not only at the time of packing, but also changes during storage. It is suggested that in the presence of light some photosynthesis may have continued, thus reducing CO₂ in the packages. The micro-perforated packaging also appeared to adequately control water loss, which is essential to maintaining good appearance and texture.

The micro-perforated packaging decreased the potential for CO₂ build-up (Aharoni et al., 1989), but at the same time controlled water loss. Light further controlled CO₂ build-up, and it is recommended that such packaging be used.

AHARONI, N., REUVENI, A. & DVIR, O., 1989. Modified atmospheres in film packages delay senescence and decay of fresh herbs. Acta Hort. 258, 255-262.

AMODIO, M.L., PERI, G., COLELLI, G., CENTONZE, D. & QUINTO, M., 2005. Effects of atmosphere composition on postharvest quality of fresh basil leaves. Acta Hort. 682, 731-735.

LOPRESTI, J. & TOMKINS, B., 1997. Postharvest handling and packaging of fresh herbs. Rural Industries Research and Development Corporation of Australia 5, 7-32.

THOMPSON, A.K. 1998. Controlled atmosphere storage of fruits and vegetables. CAB International, Wallingford.

Keywords: packaging, shelf life, fresh-cut, basil, rosemary,

Abstract # 1212: A Paper on Crop production / Gewasverbouing
SCANNING THE EFFICACY OF A NEW GENERATION TRANSPORT VESICLE FOR USE WITH PLANT REMEDIES IN AGRICULTURE

Buitendag, RA ¹, Pretorius, JC¹, Buitendag, CD¹ and Labuschagne , A¹

¹University of the Free State, PO Box 339, Bloemfontein 9300
Email: r.buitendag@agraforum-sa.com

Keywords: Adjuvant ,

Abstract # 1107: A Poster on Crop production / Gewasverbouing
ASSESSMENT OF CASSAVA–BASED CROPPING SYSTEMS AT MSELENI KWAZULU-NATAL

Buthelezi, NM¹, Allemann, J² and Ngobeni, ND³

¹University of Zululand, P/Bag X1001, KwaDlangezwa 3886; ²University of The Free State, P.0 Box 339, Bloemfontein 9300; ³ARC, Institute for Industrial Crops, P/Bag X82075, Rustenburg 0300
Email: mbuthele@pan.uzulu.ac.za

Keywords: Cassava, cropping systems

Abstract # 1075: A Paper on Soil fertility / Grondvrugbaarheid
FARMERS’ SOIL FERTILITY PERCEPTION AND ASSESSMENT IN EZIGENI AND OGAGWINI VILLAGES, KWAZULU-NATAL, SOUTH AFRICA

Buthelezi, NN¹, Hughes, JC¹ and Modi, AT²

¹School of Environmental Sciences, University of KwaZulu-Natal, Scottsville 3209; ²School of Agricultural Sciences & Agribusiness, University of KwaZulu-Natal, Scottsville 3209
Email: cphokazee@gmail.com

Keywords: Soil fertility , Indicators

Abstract # 1091: A Paper on Industry research presentations / Industrie - navorsing
CAN DEMONSTRATION PLOTS IMPROVE WEED CONTROL PRACTICES OF EMERGING FARMERS?

Campbell, PL¹, Gillespie, WA¹ and Phewa, F¹

¹SASRI P Bag X02 Mt Edgecombe 4300 KwaZulu Natal
Email: peta.campbell@sugar.org.za

Keywords: Cynodon dactylon, sugarcane, emerging farmers, demonstration plots, technology transfer,

Abstract # 1213: A Paper on Soil physics / Grondfisika
GEOPHYSICS FOR GROWTH THE LATEST IN SOIL & CROP SCIENCE GEOPHYSICS: WHAT CAN IT DO FOR YOU?

Cassidy, NJ¹

¹Keele University, Staffordshire, ST5 5BG, U.K.
Email: n.j.cassidy@esci.keele.ac.uk

Keywords: Geophysics, non-invasive investigation, soil and crop sciences ,

Abstract # 1120: A Poster on Crop production / Gewasverbouing
LABLAB PRODUCTION IN THE LIMPOPO PROVINCE OF SOUTH AFRICA AND ITS MULTIPURPOSE USES

CHUENE, MM¹, AYODELE, V I¹, MARIGA, I K¹ and WHITBREAD, A²

¹School of Agricultural and Environmental Sciences, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa; ²CSIRO Sustainable Ecosystems, 306 Carmody Road, St Lucia, Queensland 4067, Australia
Email: chenem@ul.ac.za

Keywords: lablab, biomass production, nodulation, smallholder farmers

Abstract # 1124: A Poster on Soil biology / Grondbiologie
MICROBIAL BIOMASS IN RECLAIMED SOILS FOLLOWING COAL MINING IN VIRGINIA, USA

Clayton, HG¹, Wick, AF² and Daniels, WL³

¹University of the Free State, Dept of Crop, Soil, and Climate Sciences, Internal Box 54, Bloemfontein 9300 RSA; ²246 Smyth Hall (0404), Blacksburg, VA 24061 USA; ³244 Smyth Hall (0404), Blacksburg, VA 24061 USA
Email: claytonhg@ufs.ac.za

Keywords: succession, chronosequence, Appalachian hardwoods, soil quality

Abstract # 1146: A Poster on Crop protection / Gewasbeskerming
EXSEROHILUM TURCICUM RESISTANCE OF SOUTH AFRICAN ULTRA-SHORT-SEASON MAIZE HYBRIDS

Craven, M¹ and Morey, L²

¹ARC-Grain Crops Institute, P/Bag X1251, Potchefstroom 2520; ²ARC-Biometry Unit, PO Box 8783, Pretoria 0001
Email: cravenm@arc.agric.za

Keywords: Disease progress curves, Exserhilum turcicum, resistance, maize

Abstract # 1069: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
POSTHARVEST PIGMENT AND CARBOHYDRATE CHANGES IN RELATION TO THE INCIDENCE OF RIND BREAKDOWN OF ‘NULES CLEMENTINE’ MANDARIN FRUIT

Cronje, PJR¹, Barry, GH² and Huysamer, M³

¹Citrus Research International, Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602, South Africa; ²GCM Variedades Vegetales, Valencia, Spain; ³Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602, South Africa
Email: paulcronje@sun.ac.za

Keywords: Citrus, Rind breakdown, Carbohydrates, Postharvest , Physiological disorder,

Abstract # 1139: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
NAA EFFECTIVELY THINS TABLE OLIVES IN THE “ON” YEAR THEREBY DECREASING ALTERNATE BEARING AND INCREASING FRUIT QUALITY

Crous, JJ¹ and Steyn, WJ¹

¹Department of Horticulture, Stellenbosch University, P/Bag X1, Stellenbosch, 7600
Email: crous.jacques@gmail.com

Keywords: NAA, Chemical thinning, Olea europaea, Biennial bearing

Abstract # 1186: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
EFFICACY OF MYCORRHIZAL INOCULATION ON THE GROWTH AND NUTRITION OF TOMATO (SOLANUM LYCOPERSICUM) IN THE PRESENCE AND ABSENCE OF A MYCORRHIZAL STIMULANT, IN SAND-BASED HYDROPONIC CULTURE.

Cwala, Y¹, Meyer, AH², Laubscher, CP¹ and Ndakidemi, PA¹

¹Department of Horticultural Sciences, Faculty of Applied Sciences, Cape Peninsula University of Technology, P.O. Box 652, Cape Town, 8000, South Africa; ²ARC Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch, 7599
Email: CwalaY@arc.agric.za

Keywords: arbuscular mycorrhiza, inoculant, hydroponic, stimulant, tomato, root colonization

Abstract # 1064: A Poster on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
THE INFLUENCE OF VARIETY AND SEASON ON CACTUS PEAR FRUIT JUICE: A SENSORY QUALITY EVALUATION

De Wit, M¹, Rothman, M¹, Bothma, C¹ and Hugo, A¹

¹Dept. of Microbial, Biochemical and Food Biotechnology, University of the Free State, PO Box 339, Bloemfontein, 9300
Email: dewitm.sci@ufs.ac.za

The adaptation of cactus pear (Opuntia ficus-indica) to arid and semi-arid climates allows them to be an interesting agricultural resource. It can be cultivated in areas that offer very little growth possibility for common fruit and vegetables (Saenz, 2000). Fruit quality is highly influenced by environmental characteristics, such as climate and rainfall. The objective of the study was to evaluate the effect of variety and season on the sensory quality of fruit juice from cactus pears cultivated using standardised orchard management methods (Potgieter, 1997).

Fresh fruit juice samples from 33 cactus pear cultivars were evaluated sensorically by means of Free-Choice Profiling (FCP) by ten semi-naïve panellists over two agricultural seasons: A (2006/2007) and B (2007/2008) to determine if differences exist between varieties. Cultivars included 31 Opuntia spp. and 2 Robusta spp (used as animal fodder). The fruit was peeled and the juice extracted manually. For each of the two seasons, two evaluation sessions per day were scheduled with a 60 min rest period between each session, amounting to a total of 5 cultivars per session. Ten cultivars were tested each day. The whole range of 33 cultivars was evaluated over 3 days. The whole process was repeated two weeks later. Generalized Procrustes Analysis (GPA) provided data on inter-relationships between samples and assessors and together with Principle Component Analysis (PCA) indentified the principle variables between varieties (Deliza et al., 2004).

Among the ten panellists, FCP generated 21 idiosyncratic descriptors for the attribute taste, e.g. “sweet”, “prickly pear”, “fruity”, “melon”, etc. The frequency of use of the descriptors for seasons A and B indicated clear differences between the two seasons. The GPA biplot indicated that the assessors could clearly distinguishbetween seasons A and B, since the 33 cultivars from season A were all situated to the right hand side of the figure and those from season B on the left side. The two cultivars used mainly for animal feed (Robusta spp.), Robusta and Monterey, were characterized by descriptors “sour”, “pungent”, “vegetable”, “bitter”, “beetroot” and “raw potato” and were clearly distinguished from the 31 cultivars for human consumption. The assessors were not successful in distinguishing among the 31 cultivars.

The effect of variety on fruit juice sensory quality was evident by the distinction between the fodder varieties and the human consumption varieties. No distinction could however be made among the 31 cultivars because of using an untrained panel. The influence of the season was evident from the PGA biplot results.

DELIZA, R. 2004. The consumer sensory perception of passion-fruit juice using free-choice profiling. J. Sensory Studies 20:17-27.

POTGIETER, JP. 1997 Guidelines for the cultivation of cactus pear for fruit production purposes. Second revised Edition, Group 7 Trust Publishers, Pretoria, South Africa

SAENZ, C. 2000. Processing technologies: an alternative for cactus pear (Opuntia spp.) fruits and cladodes. J. Arid Environ 46:209-225.

The authors would like to thank Dr. Herman Fouche and the ARC for providing the cactus pear fruit as well as the NRF and UFS Strategic Cluster 4 for funding.

Keywords: cactus pear, free-choice profiling, generalized Procrustes analysis, sensory, quality,

Abstract # 1126: A Paper on Crop breeding & adaptation / Gewasveredeling & aanpassing
A BREEDING PROGRAM TO ENHANCE MAIZE RESISTANCE TO BIOTIC STRESS: I. NORTHERN CORN LEAF BLIGHT RESISTANCE IN TROPICAL INBREDS

Derera, J¹, Sibiya, J¹, Magorokosho, C², Van Rij, N³ and Qwabe, F.N.P⁴

¹African Centre for Crop Improvement School of Agricultural Sciences & Agribusiness, University of KwaZulu-Natal, P/Bag X01, Scottsville 3209, South Africa; ²International Maize and Wheat Improvement Center (CIMMYT), P.O. Box MP163, MT Pleasant, Zimbabwe; ³Crop Protection, Cedara Agricultural Research Station, KwaZulu-Natal (KZN)Department of Agriculture, Environmental Affairs and Rural Development, P/Bag X9059, Pietermaritzburg, South Africa; ⁴Makhathini Research Station, KZN Department of Agriculture, Environmental Affairs & Rural Development, P/Bag X004, Jozini 3969, South Africa
Email: dereraj@ukzn.ac.za

INTRODUCTION

The staple food, maize is grown without fungicide protection in sub-Saharan Africa. Therefore recent upsurge of northern corn leaf blight disease (NLB), caused by Exserohilum turcicum, threatens maize grain productivity with negative impact on food security. With the aim of breeding for resistance to NLB in maize varieties, 2000 F₃ to F₇ inbred progenies (hybrid parents), from the program at the University of KwaZulu-Natal and CIMMYT program in Harare, were evaluated in nurseries.

MATERIALS AND METHODS

Single row plots of 5 m were established for each inbred at Cedara and Ukulinga Research Farms during the 2007/8 and 2008 /9 summer and at Makhathini Research Station during the 2009 winter. One set of hybrids, check inbreds and test inbreds was replicated twice at Cedara, but most test inbreds were not replicated. Standard cultural practices except fungicide application were followed. Irrigation was applied to supplement rainfall at Ukulinga and Makhathini. Nurseries were subjected to natural infection and were rated at the hard dough stage using a 1 (resistant) to 9 (susceptible) scale.

RESULTS AND DISCUSSION

Results indicated high level of disease incidence with highly significant (P≤0.01) genetic variation for disease scores. Disease scores of inbreds ranged from resistant to very susceptible depending on their background. Severity scores were highest in late planted nurseries. Popcorn inbreds were very susceptible; whereas the dent and flint subtropical inbreds were less vulnerable to NLB than their tropical counterparts reflecting their superior adaptation to these South African environments. Genetic analysis of hybrids involving a sample of the inbreds revealed that predominantly genes with additive effects (75-86%) controlled resistance, while genes with non-additive effects played a minor (14-25%) but significant role. Therefore breeding procedures that emphasise general combining ability will be used to enhance the resistance in inbreds, while specific combining ability will be exploited in designing hybrids for deployment in sub-saharan Africa.

CONCLUSION

Overall results indicated huge genetic variation which can be exploited in a breeding program to enhance NLB resistance in maize varieties targeted at African ecosystems.

ACKNOWLEDGEMENT

The maize breeding program at the University of KwaZulu-Natal is funded by the Alliance for a Green Revolution in Africa.

Keywords: Disease resistance, Exserohilum turcicum, genetic variation, maize inbred lines, northern corn leaf blight, plant breeding program

Abstract # 1211: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
SOIL INFORMATION AND EDUCATION FOR A SUSTAINABLE MANAGEMENT: THE SOIL ATLAS OF AFRICA

Dewitte, O¹

¹1Land Management & Natural Hazards Unit, SOIL Action, IES – Institute for Environment and Sustainability
Email: lerouxpa.sci@ufs.ac.za

Keywords: soil atlas ,

Abstract # 1132: A Paper on Soil chemistry / Grondchemie
THE EFFECT OF CHICKEN MANURE ON SOILS CHEMICAL PROPERTIES IN SELECTED SOIL TYPES IN BOTSWANA

Dikinya, O¹ and Mufwanzala, N¹

¹Department of Environmental Science, University of Botswana, P/Bag 0022, Gaborone
Email: dikinyao@mopipi.ub.bw

Keywords: chicken manure, soil chemical properties, soil types, Botswana

Abstract # 1208: A Paper on Keynote speech
THE IMPORTANCE AND FUTURE OF WEED SCIENCE

Duke, SO¹

¹USDA, ARS, NPURU, P. O. Box 8048, University, MS 38677, USA
Email: Stephen.duke@ars.usda.gov

Keywords: HRC ,

Abstract # 1087: A Paper on Hort nutrition & water management / Tuinbou voeding & waterbestuur
INTEGRATING HYPERSPECTRAL AND PHYSIOLOGICAL DATA TO DETERMINE THE WATER STATUS OF SATSUMA MANDARIN TREES

Dzikiti, S¹, Verreynne, JS¹, Stuckens, J¹, Strever, A¹, Verstaeten, WW¹, Swennen, R¹ and Coppin, P¹

¹Department of Horticultural Science, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
Email: sdzikiti@sun.ac.za

Traditional irrigation scheduling of crops normally involves indirect monitoring of environmental variables e.g. climatic and /or soil water conditions. Irrigation scheduling based on detecting drought stress directly from the plants is currently a subject of scientific interest because many aspects of the plant's physiology respond directly to changes in the water status in the plant tissues rather to changes e.g. in the bulk soil water content. In this study we investigate the potential of hyperspectral sensing as a tool for plant-based stress detection. We propose a method which integrates hyperspectral and physiological data to improve the accuracy of estimates of tree water status.  

Leaf reflectance of young potted citrus trees subjected to different drought stress regimes was monitored outdoors using an ASD spectroradiometer that detects reflectance in the 350 - 2500 nm spectral region at fine spectral resolutions. Water status indicators commonly used for irrigation scheduling namely the midday stem, midday leaf, and predawn leaf water potentials were quantified with the leaf water content and sap flow as ancillary data. Relationships between changes in leaf reflectance and the drought stress indicators were determined using existing spectral indices, logistic regression and a tree level water balance model.

Most spectral indices were highly correlated with the leaf water content of both stressed and unstressed trees with a narrow band spectral ratio of the reflectance at 960 and 950 nm giving the highest leaf water content estimates for citrus leaves. The spectral indices predicted fairly accurately the water potentials of severely stressed trees but they failed to predict the water potentials of the moderately stressed and unstressed trees with R²<0.20. However, using the leaf water content data predicted by the spectral methods on unstressed trees as inputs to the tree water balance model significantly improved the midday stem water potential estimates with sap flow as the other model input.  

Hyperspectral indices seem to have a limited use in directly predicting the water potential of trees under light drought stress. Integrating the hyperspectral with physiological data potentially improves the accuracy of prediction of the stem water potential although this approach still needs to be evaluated under field conditions.    

We acknowledge funding from the collaboration between Stellenbosch University and the Katholieke Universiteit Leuven, Belgium and Citrus Research International.

Keywords: Citrus, drought stress, model, spectral indices, water potential,

Abstract # 1062: A Poster on Crop protection / Gewasbeskerming
POST RELEASE MONITORING OF LEPIDOPTERA ON BT AND NON-BT MAIZE AT SIX SITES IN THE VAALWATER AND VENTERSDORP AREAS

Engelbrecht, EE¹ and Van den Berg, J¹

¹School of Environmental Sciences and Development, North West University, P/Bag X6001, Potchefstroom, 2520
Email: 20096550@puk.ac.za

Keywords: Bt-maize, Lepidoptera

Abstract # 1129: A Poster on Crop protection / Gewasbeskerming
RESPONSE OF TWO NOCTUID SPECIES, THE AFRICAN BOLLWORM AND COMMON CUTWORM, TO BT MAIZE

Erasmus, A¹, Van Rensburg, JBJ¹ and Van den Berg, J²

¹ARC - Grain Crop Institute, P/Bag X1251, Potchefstroom 2520; ²School of Environmental Sciences and Development, North-West University, Potchefstroom 2520
Email: ErasmusA@arc.agric.za

Transgenic maize (Bt) was introduced in South Africa for control of the lepidopterous stemborers, Busseola fusca Fuller (Noctuidae) and Chilo partellus Swinhoe (Crambidae) during 1998. Other noctuid species, including the cutworm Agrotis segetum Denis & Schiffermüller (injurious to seedlings) and African bollworm Helicoverpa armigera Hübner (ear feeder), are exposed to Bt toxin for a part of their life cycle, although neither pest is regarded as a target for Bt-technology. In the present study the effect of Bt maize on the growth and survival of both A. segetum and H. armigera was investigated.

A laboratory study was conducted in which survival, mass gain and pupation of A. segetum 4^th instar larvae were recorded when fed on Bt- and non-Bt maize seedlings. The following varieties were used: DKC 7815B (transgenic, MON810), CRN 3505 (non-Bt iso-hybrid for DKC 7815B), NK Mayor B (transgenic, Bt11), and Brasco (non-Bt iso-hybrid for NK Mayor B). The longevity and fecundity of moths of A. segetum derived fromsurviving larvae were also recorded. Helicoverpa armigera larval survival and mass gain on Bt- and non-Bt maize ears were evaluated in a greenhouse trail. The hybrids tested were DKC 78-15B (event MON810) with iso-hybrid CRN 3505. Probability of the study is indicated by P<0.05.

No significant differences in mass and larval survival of A. segetum when feeding on any of the hybrids were observed. The incidence of pupation of larvae over time was higher on Brasco than on NK Mayor B, with no differences between CRN 3505 and DKC 7815B. Moths originating from larvae feeding on Brasco produced more eggs than those from NK Mayor B. Fertility was significantly higher in moths originating from larvae feeding on DKC 7815B compared to the other hybrids. The mean longevity of female or male moths did not differ between any of the hybrids. Larvae feeding on Brasco reached higher percentage pupation over a shorter period of time compared to larvae feeding on NK Mayor B.

Mass of H. armigera larvae feeding on DKC 7815 B ears were lower than larvae feeding on CRN 3505 ears. Mass of larvae feeding on the Bt hybrid did not increase over time but a consistent increase was observed when feeding on the non-Bt hybrid. Larval survival differed significantly between Bt and non-Bt ears for hybrid CRN 3505 and DKC 7815 B. Helicoverpa armigera larvae feeding on Bt ears were always smaller than larvae feeding on non-Bt hybrids which contributed to a delay in development. This may result in much less ear damage on Bt than non-Bt plants.

This study indicated that Bt maize will most likely not have a significant effect on the biology of A. segetum under field conditions. The study also quantified the effect of Bt maize on H. armigera and provided important information on the potential of Bt maize to protect maize ears from feeding damage.

Keywords: Agrotis segetum, Bt maize, feeding studies, Helicoverpa armigera

Abstract # 1189: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
EFFECT OF HYDROGEN CYANAMIDE, MINERAL OIL AND THIDIAZURON IN COMBINATION WITH TIP PRUNING, ON BUD BREAK IN 'EVITA' FIG

Gerber, HJ¹, Steyn, WJ¹ and Theron, KI¹

¹Department of Horticultural Science, Stellenbosch University, P/Bag X1, Matieland, 7602
Email: hjg@sun.ac.za

Keywords: dormancy, Ficus carica L., harvest scheduling, rest breaking

Abstract # 1190: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
VEGETATIVE AND REPRODUCTIVE PHENOLOGY OF 'EVITA' FIG (FICUS CARICA L.) UNDER SOUTH AFRICAN CONDITIONS

Gerber, HJ¹, Steyn, WJ¹ and Theron, KI¹

¹Department of Horticultural Science, Stellenbosch University, P/Bag X1, Matieland, 7602
Email: hjg@sun.ac.za

Keywords: commercial practices, yield, pruning, shoot length

Abstract # 1080: A Poster on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
PRELIMINARY STUDIES ON THE UPTAKE OF COMMERICAL POST HARVEST PRODUCTS BY GERBERA MAXI CULTIVAR ‘OPTIMA’

Hannweg, K¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: karin@arc.agric.za

Cut flowers are supplied to many markets world-wide and, as with most fresh products, require specific post harvest handling to ensure that quality after harvest is maintained for as long as possible. Cut flowers should be harvested at the correct maturity, under the appropriate conditions, and handled according to the variety’s specific requirements. All handling, from harvest to market, will significantly affect the quality and longevity of the flowers - one of the most important steps requires that flowers be adequately hydrated before shipping to customers to ensure that maximum vase-life is obtained. Two commercial products developed for use by farmers were tested for their uptake potential and were compared with the currently used post harvest treatment for Gerbera cut flowers grown by the Timbali Technology Incubator growers.

Harvested flowers were treated with either Product A, B (both commercial products) or C (currently used as a post-harvest treatment and is not a commercial product). All three products are chlorine-based. Flowers were harvested at the two-ring stage and were delivered to the laboratory within 30 minutes of harvesting. Solution uptake was recorded over a period of five hours. The trial was repeated three times.  After treatment, flowers were placed in vases containing slightly acidified water (pH 6.0) containing a surfactant and maintained under ambient conditions to simulate customer conditions.

Trends in uptake indicated that the flowers became less hydrated, i.e. appeared to lose water through transpiration over time for Products A and B compared with those flowers placed in Product C, which took up more solution during the trial. Solution pH may have played a role in uptake in that Products A and B had an extremely high average pH (pH 6.81 for Product A and pH7.56 for Product B) in comparison with Product C (3.56). Hydration solutions with a high pH are not readily taken up by flower stems, although sterilising chlorine species are more active in neutral pH solutions. However, it appears that combined with the low pH which facilitates water uptake, the lower pH level of Product C may in addition prevent bacterial bloom, thus further promoting uptake.

The commercial products did not promote uptake of water and the flowers rather appeared to lose water over time. Although this did not appear to affect the vase-life compared with Product C, it would not be economically feasible for farmers to make use of these commercial products without there being a major benefit in enhancing vase-life. It is extremely important that producers ensure that the products they are using are providing the benefits they require.

Timbali Technology Incubator staff and beneficiaries are thanked for providing the plant material for the trial. Ms Shirley Sihlangu, Ms Zodwa Ndimande and Ms Lucy Mthethwa from the Agricultural Research Council (ARC) are thanked for their assistance in the laboratory. The ARC partially funded the study.

Keywords: hydration, cut flower, post harvest quality, solution uptake

Abstract # 1079: A Paper on Hort biotechnology, breeding &development / Tuinbou biotegnologie, veredeling & ontwikkeling
PHYSICAL, BIOCHEMICAL AND MOLECULAR METHODS FOR THE IDENTIFICATION OF HYBRID EMBRYOS DERIVED FROM CONTROLLED POLYEMBRYONIC CITRUS ROOTSTOCK CROSSES

Hannweg , K¹ and Visser, G¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: karin@arc.agric.za

Keywords: zygotic embryos, nucellar embryos, molecular analysis ,

Abstract # 1192: A Paper on Soil chemistry / Grondchemie
CHARACTERISATION OF RAW AND CHEMICALLY OXIDISED BIOCHAR FOR USE AS A SOIL AMENDMENT

Hardie, AG¹, De Lange, L² and Hoffman, JE¹

¹Dept. Soil Science, Stellenbosch University, P/Bag X1, Matieland 7602; ²Sudor Carbon Sciences (Pty) Ltd, PO Box 1053, Stellenbosch 7599
Email: aghardie@sun.ac.za

Keywords: biochar, CEC

Abstract # 1199: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
EFFECT OF FERMENTATION TEMPERATURE AND TIME ON CHEMICAL COMPOSITION OF BUSH TEA (ATHRIXIA PHYLICOIDES)

Hlahla, LN¹, Mariga , IK and Mudau, FN

¹Department of Soil Science, Plant Production and Remote Sensing, University of Limpopo, P/Bag X1106, Sovenga, 0727
Email: l.hlahla@webmail.co.za

Athrixia phylicoides (DC.), commonly known as bush tea, is indigenous to South Africa. It is used as a herbal tea and a medicinal plant by traditional African people (Roberts, 1990). McGaw et al. (2007) reported that bush tea leavescontain no caffeine or pyrrolizidine alkaloids, justifying its medical potential. Total polyphenols in tea leaves are the main indicators for medicinal potential due to their antioxidant activities (Hirasawa et al., 2002). This study was initiated to determine the effect of fermentation temperature and time on the quality of bushtea.

Fermentation temperatures and times were investigated separately, with each treatment replicated three times. Temperature treatments comprised 24°C (control), 30°C, 34°C, 38°C and 42°C, with the tea leaves being fermented for 30 minutes in an incubator. To determine the optimal time, fermentation was carried out for 0 (control), 60, 90 and 120 minutes at 22-26°C in an incubator. Chemical analyses (polyphenols, tannins and antioxidants) were according to the methods of Waterman and Mole (1994).

This study demonstrated that fermentation temperatures of 30, 34 and 38°C significantly increases polyphenols, whereas tannin content showed a great reduction at 38 and 42°C. Increasing fermentation time achieved a significant increase in both polyphenols (60 and 90 minutes) and tannin contents (90 and 120 minutes). However, changes in either fermentation temperature or time did not have a significant influence on antioxidant content of bush tea.

Different fermentation temperatures and times of bush tea exhibited significant influence on polyphenol and tannin contents, but had no influence on the antioxidant content of the tea. Further studies are required to determine the sensory quality parameters, such as taste and aroma.

HIRASAWA, M., TAKADA, T., MAKIMURA, M. & OTAKE, O., 2002. Improvement of periodontal status by green tea catechin using a local delivery system: A clinical pilot study. J. Periodontal Res. 37, 433-438.

 McGAW, L.J., STEENKAMP, V., & ELOFF, J.N., 2007. Evaluation of Athrixia bush tea for cytotoxicity, antioxidant activity, caffeine content and presence of pyrrolizidine alkaloids. J. Erthnopharmacol. 110(1), 16-22.

ROBERTS, M., 1990. Indigenous Healing Plants (first edition), Southern Book Publishers, Halfway House, South Africa.

WATERMAN, P. & MOLE, S., 1994. Analysis of phenolic plant metabolites p. 85 – 88. Blackwell Scientific, London.

The authors would like to thank Tshumisano for providing funds.

Keywords: Athrixia phylicoides, fermentation, temperature, chemical composition

Abstract # 1194: A Poster on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
TOWARDS IMPROVING LONGEVITY OF CUT LILIUM ‘ACAPULCO’

Hoffman, EW¹

¹Department of Horticulture, Stellenbosch University, P/Bag X1, Matieland, 7602
Email: ewh@sun.ac.za

Keywords: ethylene, floriculture, postharvest, respiration

Abstract # 1145: A Poster on Crop quality / Gewaskwaliteit
EFFECT OF SEED DRESSINGS AND SEED SIZE ON MAIZE GERMINATION AFTER STORAGE

Hugo, E¹, Van der Walt, MM¹ and Saayman-du Toit, AEJ¹

¹ARC-grain Crops Institute, P/Bag X1251, Potchefstroom 2520
Email: hugoE@arc.agric.za

Keywords: germination, maize, storage, seed dressing

Abstract # 1207: A Paper on Keynote speech
MORE SUGAR WITH LESS WATER IN THE AUSTRALIAN SUGAR INDUSTRY

Inman-Bamber, G¹

¹Principal research scientist, CSIRO Plant Industry, Davies Lab, Townsville Australia
Email: @

Keywords: sucrose accumulation ,

Abstract # 1137: A Poster on Soil fertility / Grondvrugbaarheid
TRENDS IN SOIL NUTRIENT STATUS OF CROPPED SOILS IN LOW EXTERNAL INPUT FARMING SYSTEMS OF THE EASTERN CAPE PROVINCE

Jezile, GG¹ and Turner, DP¹

¹600 Belvedere Street, ARC-ISCW, Arcadia, Pretoria 0001
Email: jezileg@arc.agric.za

Keywords: cultivated and uncultivated lands, fields, home gardens, small-scale agriculture, soil fertility status,

Abstract # 1093: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
CHILLING INJURY IN ‘EUREKA’ LEMONS: COULD POLYAMINES REDUCE THE INCIDENCE?

Jordaan, SCP¹, Taylor, NJ¹ and Robbertse, PJ¹

¹Department of Plant Production and Soil Science, University of Pretoria, Pretoria, 0002
Email: scpjordaan@tuks.co.za

The polyamines (PAs) putrescine, spermidine and spermine are ubiquitous molecules, present in both plants and animals. They are believed to play roles in a wide variety of plant functions, from floral initiation to rhizogenesis and cell division. The ability of PAs to impact these functions suggests that they could perhaps be used as a plant growth regulator to influence fruit set or fruit growth and fruit quality. The potential of PAs to reduce Chilling injury (CI) occurrence in lemons was investigated, as these molecules influence membrane permeability and cell wall rigidity.

CI was simulated by storing lemons in a cold room set at 2 °C ± 2 °C. Storage conditions were adapted from USDA Phytosanitary Requirements for citrus export. Temperature and relative humidity within the cold room were measured at regular intervals. Harvest-ready lemons were treated with two concentrations i.e. 1mM and 0.1mM of the three PAs, putrescine, spermidine and spermine, seven days prior to harvest. An untreated control was included. Following harvest these lemons were stored in a cold room. Additional lemons were also treated post-harvest by dipping them in the same concentrations of PAs for 30 seconds, following which they were transferred to the cold room. CI was evaluated after 48 days of storage and PA levels within the fruit rind quantified using HPLC. Micrographs were prepared to investigate the effects of PA applications on cell membranes. A complete randomized design was used, with 40 replicates of each treatment. The Kruskal-Wallis test was performed to test for significant differences between treatments and a t-test (LSD) to determine differences between means with a probability level of 0.05%.

CI could be found under simulation conditions on treated and control fruit. These symptoms occurred mainly in the rind of the fruit, without greatly influencing internal fruit quality. Occasionally CI was found on the whole fruit surface, rendering fruit soft to the touch, and when cut open the rind had a halo-like appearance. Certain PA-treatments appeared to reduce the incidence of CI, but this was dependent on the timing of application, the PA applied and the concentration thereof.

PAs could be used as a possible method to reduce CI in export citrus fruit. The reduction in CI is a result of interaction with cell membranes, reducing membrane permeability and increasing cell wall rigidity.

Keywords: Chilling Injury, polyamines, putrescine, spermidine, spermine,

Abstract # 1099: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
EFFECT OF SILICON APPLICATION ON 'HASS' AVOCADO FRUIT PHYSIOLOGY

Kaluwa, K¹, Bertling, I¹ and Bower, JP¹

¹Horticultural Science, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, Pietermaritzburg
Email: kaluwa.k@gmail.com

Keywords: Avocado, Silicon, Fruit firmness, carbon dioxide, ethylene,

Abstract # 1070: A Poster on Crop production / Gewasverbouing
EFFECT OF PLANT POPULATION, ROW SPACING AND NITROGEN APPLICATION RATES ON KENAF PRODUCTION

Kayembe, KP¹

¹Department of Plant Production and Soil Science, University of Pretoria, Pretoria 0002
Email: s28663447@tuks.co.za

INTRODUCTION

Keywords: Kenaf, Multipurpose crop, Growth characteristics, Biomass production

Abstract # 1182: A Poster on Crop nutrition & water / Gewasvoeding & water
IRRIGATION FREQUENCY AND PHOSPHATE APPLICATION RATE OF HYDROPONICALLY GROWN TOMATOES

Kempen, E¹

¹Department of Agronomy, Stellenbosch University, P/Bag X1, Matieland 7602
Email: estellek@sun.ac.za

Keywords: Fertigation frequency, hydroponics, phosphate, tomato

Abstract # 1159: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
LOW TEMPERATURE SHIPPING AND COLD CHAIN MANAGEMENT OF ‘HASS’ AVOCADOS: AN OPPORTUNITY TO REDUCE SHIPPING COSTS

Kok, RD¹, Bower, JP and Bertling, I

¹Horticultural Science, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, P/Bag XO1, Scottsville, 3209, Pietermaritzburg, South Africa
Email: 206507812@ukzn.ac.za

With the South African avocado industry being largely export orientated, new and effective technologies are vital to improve quality and shelf life. The ‘Hass’ cultivar comprises 50% of South African avocado exports. Current technologies to delay ripening, such as 1-MCP and CA, are costly and have disadvantages (Maré et al., 2002). It has been shown that breaks in the cold chain are highly detrimental to fruit quality, even if the fruit recover to normal physiological functioning. Premature softening, mass loss and colour change resulted from cold chain breakage in Chilean fruit (Undurraga et al., 2007). This study examined whether storage at 1°C is comparable to 1-MCP during simulated shipping, and ascertained the effects of cold chain breaks on the final fruit quality of ‘Hass’ avocados.

‘Hass’ avocado fruit were subjected to treatments of temperature (1^oC and 5.5^oC), 1-MCP (treated and untreated), waxing (waxed and non-waxed) and cold chain breaks (no break, 24 hour delay, break at 5, 10 and 20 days). The 40 treatment combinations (10 fruit each) were placed into simulated shipping for 28 days. The weight, fruit softness, water content, CO₂, ethylene, and days to ripening were measured and recorded. Statistical analysis was conducted in the form of a factorial design in order to determine significant differences between the treatments used.

The results indicated that the effect of ripening with the use of 1^oC was comparable to the use of 1-MCP, although 1-MCP slightly extended the time to ripening. There were signs that the occurrence of cold chain breaks did in fact reduce the quality and ripening period, but results were variable. It was interesting to note that the temperature of 1^oC nullified the effect of the breaks to some extent.

It is possible that 1^oC will be the protocol temperature for the ‘Hass’ cultivar due to the advantageous effects. This temperature may not entirely match the performance of 1-MCP, but it may be a viable alternative with respect to the economics involved. The effect of cold chain breaks are also reduced at this temperature but the physiological aspects still need to be investigated.

MARÉ, L., TRUTER, A.B., DODD, M.C. & HOLCROFT, D.M., 2002. The use of CA storage, CO₂ shock treatments and / or 1-MCP treatments on ‘Fuerte’ and ‘Hass’ avocados. S. Afr. Avocado Growers’ Assoc. Yrbk. 25, 35-44.

UNDURRAGA, P., OLAETA, J.A. & SAN MARTIN, J., 2007. Effect of Temperature Break in the Behaviour of Avocados (Persea americana Mill.) Hass cv. During Refrigerated Storage. Proceedings VI World Avocado Congress, Viña Del Mar, Chile.

Keywords: low temperature shipping, 1-MCP, cold chain breaks ,

Abstract # 1060: A Paper on Crop protection / Gewasbeskerming
LOW LEVELS OF REFUGE COMPLIANCE RESULTED IN RESISTANCE DEVELOPMENT OF THE MAIZE STEM BORER TO BT MAIZE AT THE VAALHARTS IRRIGATION SCHEME

Kruger, M¹, Van Rensburg, JBJ² and Van den Berg, J¹

¹North-West University, School of Environmental Sciences and Development, Private Bag X6001, Potchefstroom, 2520, South Africa.; ²ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom, 2520, South Africa
Email: marlene.kruger@nwu.ac.za

Keywords: Bt-maize, Busseola fusca, refuge compliance, resistance development

Abstract # 1154: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
COMPARISON OF THE DEGREE OF WATER SATURATION OF SELECTED DIAGNOSTIC HORIZONS IN THE CATHEDRAL PEAK VI AND WEATHERLEY CATCHMENTS

Kuenene, BT¹, Le Roux, PAL¹, Van Huyssteen, CW¹ and Hensley, M¹

¹University of Free State, Department of Soil, Crop and Climate Sciences, P.O. Box 339, Bloemfontein 9300
Email: kuenenebt.sci@ufs.ac.za

Keywords: saturation, soil water regime, redox, porosity

Abstract # 1142: A Poster on Weed management / Onkruidbestuur
EFFECTS OF FIVE MANAGEMENT PRACTICES ON WEED SPECTRUM IN A CHARDONNAY/ 99 RICHTER VINEYARD

Kutama, TG¹, Fourie, JC² and Kunjeku, EC¹

¹University of Venda, P/bag X 5050, Thohoyandou 0950; ²ARC, Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch 7599
Email: thifheli@univen.ac.za

ACKNOWLEDGEMENTS

Keywords: management practices , grapevines, weed stand, weed spectrum

Abstract # 1168: A Paper on Hort nutrition & water management / Tuinbou voeding & waterbestuur
BASELINING THE NUTRIENT ELEMENTS OF MIMUSOPS ZEYHERI UNDER NATURAL CONDITIONS

Ledwaba, CR¹, Mafeo, TP², Mashela, PW² and Mphosi, MS²

¹Limpopo Department of Agriculture, P/Bag X9487, Polokwane, 0700, South Africa; ²School of Agricultural and Environmental Sciences, University of Limpopo, P/Bag X1106, SOVENGA, 0727, South Africa
Email: Ledwabac@agric.limpopo.gov.za

Mimusops zeyheri, indigenous to south Saharan Africa, has fruits with highest vitamin C among both exotic and indigenous tested fruit trees. Currently, it is found in mountainous areas and along the rivers in Limpopo Province. Attempts are currently under way to domesticate the plant in order to use it for both aesthetic and nutritional purposes. A baseline study was conducted to determine factors that influence its nutritional status.

The experiment was arranged as a 2 x 3 factorial in a randomized complete block design, with the first and second factors being sampling time and location, respectively. Five matured leaves from fruit-bearing branches were sampled from each of the four cardinal positions. Soil samples were collected from the cardinal points at 0.5 m from the trunk using a 2-cm-diameter auger. Leaf nutrient elements were regressed against soil Ca, Cu, K, Fe, Mn, Na, Zn, P, pH (H₂O) and EC.

The stepwise regression eliminated factors that the plant was saturated with. For any nutrient element in the leaf, certain soil factors might be limiting for the accumulation of that element during fruiting, but after fruiting the same soil factors became limiting, optimal or inhibitory to the accumulation of the same element in leaves. For instance, for accumulation of Cu in leaves, Mg was inhibitory during fruiting and after fruiting, whereas it had limited effect on accumulation of K during fruiting. Identification of limiting nutrient elements could improve the determination of fertilizer requirement for this plant.

Physiological studies will be necessary to assess the importance of “limiting” mineral nutrients in the accumulation of certain mineral nutrients in M. zeyheri in relation to its productivity.

The authors are grateful to the National Research Foundation for funding the study.

Keywords: Mimusops zeyheri, nutrient elements, stepwise regression ,

Abstract # 1081: A Poster on Crop protection / Gewasbeskerming
EFFECTS OF IMIDACLOPRID AND ENVIRONMENT ON GERMINATION OF DRYLAND WHEAT IN THE SUMMER RAINFALL REGION

Lindeque, RC¹

¹ARC-SGI, Private Bag X29, Bethlehem 9700
Email: lindequerc@arc.agric.za

Keywords: Wheat, Russian Wheat Aphid, Imidacloprid, Seedling germination

Abstract # 1082: A Paper on Crop protection / Gewasbeskerming
SEED DRESSING AND FOLIAR-APPLIED INSECTICIDE EFFICACY AGAINST RUSSIAN WHEAT APHID (DIURAPHIS NOXIA) ON DRYLAND WHEAT IN THE SUMMER RAINFALL REGION

Lindeque, RC¹

¹ARC-Small Grain Institute, P/Bag X29, Bethlehem 9700
Email: lindequerc@arc.agric.za

INTRODUCTIONSeed dressing, foliar-applied insecticides and host plant resistance provide protection against RWA though new biotypes may overcome genetic resistance in wheat varieties. Insecticide sprays are less environmentally friendly and may contribute excessively to input costs of the farmer. The aim of our experiment is to determine efficacy of host plant resistance in commercial wheat varieties compared to chemical control and also analyze cost implications and profitability of chemical RWA control measures in commercial wheat.

MATERIALS AND METHODSField trials using a split-split plot design with four replications were planted at ARC-SGI (Bethlehem) and Seotlong (Qwa-qwa) in 2008. Comparisons between application cost, efficacy and profitability of host plant resistance, seed dressing (Imidacloprid) and foliar insecticides (Demeton-S-Methyl/Parathion or Chlorpyriphos) applied singularly or in combination to Matlabas, Scheepers 69 (susceptible check), SST 399 and PAN 3144 (resistant check) were made. An adapted commercial precision planter with an in-row spacing of 5cm, between-row spacing of 45cm and fertilizer placement sufficient for 30kg ha-1 was used and soil moisture during planting was adequate in 2008. Seed dressing consisted of Gaucho 350FS applied at 400ml of Imidachloprid with 800ml of water to 100kg of seed. The foliar insecticides Demeton-S-Methyl (500ml/ha) + Parathion (650ml/ha) and Chlorpyriphos (850ml/ha) were applied with a knapsack sprayer delivering 100l/ha between growth stages 12 to 13. Percentage infested tillers in plots were determined between growth stage 12 to 13 before application of foliar insecticide treatments by using the recommended scouting technique for RWA. Application cost (seed, pesticide, application and risk), cultivar yield and quality were used to calculate profitability of all treatments in comparison with the untreated check for each cultivar. Data was analyzed by ANOVA using GENSTATS 8.1 for Windows (F probabilities of 0.05, 0.01 and 0.001).

RESULTS AND DISCUSSIONSeed dressing combined with insecticides increased yield significantly above the untreated check and frequently resulted in a positive growth response. In 2008 main effect of Treatments (Insecticides) was significant at Seotlong (F.pr <0.05) confirming that reduced RWA infestation from Imidacloprid treatment combined with insecticides enables wheat varieties to achieve yields closer to the genetic potential for the specific variety. Hectolitre mass of Scheepers 69 (susceptible check) was significantly increased at ARC-SGI (F.pr <0.001) and Seotlong (F.pr <0.001) by Imidacloprid and Chlorpyriphos and Demeton-s-methyl/Parathion. Though percentage RWA infestation at ARC-SGI was less than at Seotlong in 2008, marginal rainfall on shallower sandy-loam soil resulted in a mean yield of 1.85 tons ha-1 at ARC-SGI compared to 2.41 tons ha-1 at Seotlong where higher rainfall during the late wheat season on deep sandy soil increased yield.

CONCLUSIONSWith the production conditions of 2008 insecticide treatments were generally more profitable in high-yielding environments such as Seotlong as all five treatments increased profitability on three of the four wheat varieties. This trend strongly indicates that insecticides become increasingly important as the yield potential of a specific production area or field approaches optimal yielding conditions.

Keywords: Wheat, Russian Wheat Aphid, Chemical Control ,

Abstract # 1096: A Poster on Weed management / Onkruidbestuur
HERBICIDE APPLICATION RATE AFFECT THE CONTROL OF THREE ANNUAL WEED SPECIES

Liphadzi, KB¹ and Dille, A²

¹Limpopo Department of Agriculture, Private Bag X 9487, Polokwane 0700; ²Department of Agronomy, Kansas State University, Manhattan, KS 66506-5501
Email: liphadzik@agric.limpopo.gov.za

Keywords: Flumetsulam, giant foxtail, Isoxaflutole, Palmer amaranth, velvetleaf,

Abstract # 1160: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
LOW TEMPERATURE SHIPPING AND COLD CHAIN MANAGEMENT OF 'FUERTE' AVOCADOS: AN OPPORTUNITY TO REDUCE SHIPPING COSTS

Lütge, A¹, Bower, JP and Bertling, I

¹Horticultural Science, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, P/Bag XO1, Scottsville, 3209, Pietermaritzburg, South Africa
Email: 206504141@ukzn.ac.za

The South African avocado industry is largely export orientated, depending heavily on the European markets, with ‘Fuerte’ making up 25% of exports. A temperature of 5.5^oC and expensive controlled and modified atmosphere treatments are currently used to delay ripening; however, fruit still appear on the European market showing signs of softening and physiological disorders. Previous work by Bower & Magwaza (2004) showed that it is possible to ship greenskins at 2^oC, and has also been repeatedly shown to result in improved fruit quality (Van Rooyen, 2006). The extent to which cold chain breaks affect quality, and whether 1-MCP counters this, is unknown in greenskins, as is the combination with low temperature. The objective of the study was to determine the potential for shipping ‘Fuerte’ avocados at 2^oC, and to determine the effects of cold chain breaks on fruit quality. 

‘Fuerte’ avocado fruit were subjected to treatments of temperature (2^oC and 5.5^oC), 1-MCP (treated and untreated), waxing (waxed and non-waxed) and cold chain breaks (no break, 24 hour delay, break at 5, 10 and 20 days). The 40 treatment combinations were placed into simulated shipping for 28 days. Data were collected for 10 fruit (replications) for each treatment combination and analysed with respect to fruit softness, weight, water content, CO₂ levels, days-to-ripening, external quality and internal quality. A factorial design was used for the statistical analysis.

The storage temperature of 2^oC provided good internal quality as well as reduced weight loss (mainly water loss) and fruit softening. The 2^oC storage temperature did cause a notably higher occurrence of external chilling injury than 5.5^oC. The cold chain breaks showed no definitive results, but further physiological analysis of the tissue samples should highlight the effects of cold chain breaks on fruit quality.

The results indicate that a 2^oC storage temperature can improve the internal quality. Being a greenskin, the external chilling injury which occurred as a result of 2^oC storage is unacceptable and may require other mitigating treatments to negate the external chilling injury. This suggests that 1-MCP may still be required for greenskins, whereas the external injury in non-greenskins such as ‘Hass’ would be immaterial.

BOWER, J. P., MAGWAZA, L.S. 2004. Effect of coatings and packaging on external and internal quality with emphasis on cold injury. S. Afr. Avocado Grower’s Assoc. Yrbk. 27, 51-55.

VAN ROOYEN, Z., 2006. Factors affecting mesocarp discoloration severity in 'Pinkerton' avocados. Ph.D. Thesis, University of KwaZulu-Natal, Pietermaritzburg, South Africa.

Keywords: low temperature shipping, 1-MCP, cold chain breaks ,

Abstract # 1066: A Paper on Crop production / Gewasverbouing
CAN HYDROPRIMING IMPROVE GERMINATION SPEED, VIGOUR AND EMERGENCE OF MAIZE LANDRACES UNDER WATER STRESS?

Mabhaudhi, T¹ and Modi, AT¹

¹Crop Science Department, School of Agriculture and Agribusiness, University of KwaZulu-Natal, P/Bag X01, Scottsville, PMB. 3209
Email: tafadzwanashemabhaudhi@yahoo.com

Maize landraces are crop genetic resources that have evolved through natural and farmer selection. Earlier work showed that landraces may have the same viability but not vigour as hybrids. Hydropriming has recently been used to enhance seed vigour in several other crops. The aim of this study was to evaluate whether hydropriming can improve vigour characteristics and seedling emergence of a local maize landrace compared to commercial hybrids under water stress.

MATERIALS AND METHODS

The study was conducted at the University of KwaZulu-Natal, Pietermaritzburg. Seeds from a local landrace were produced and characterized according to kernel colour, white (Land A) and purple (Land B), and compared to two hybrids, SC701 and SR52, which are popular amongst local farmers. Three replications of 25 seeds from each variety were soaked in water for 0 hours (unprimed or control), 12 hours and 24 hours, and germinated between moistened double layered paper towels in a germination chamber at 25⁰C for 8 days. Parameters measured included final germination, mean germination time (MGT) and germination velocity index (GVI). Seedling emergence was performed in seedling trays, using three replications of 10 seeds from each variety and treatment, using pine bark wetted to 25% or 75% of field capacity (FC), for 21 days in a temperature-controlled glasshouse (25⁰C day; 15⁰C night; 60% RH). Parameters measured included final emergence, mean emergence time (MET), root and shoot lengths, and leaf area.  Samples of unprimed and primed seeds were analysed for soluble sugars using isocratic High-Performance Liquid Chromatography (HPLC). Data was analysed using GenStat® (Version 11) ANOVA and LSD (5%) to separate means.

Hydropriming did not improve final germination. Hybrids performed better than landraces when seeds were not primed. Priming landraces for 12 and 24 hours reduced MGT by 9% and 7%, respectively, compared to 5% in hybrids for both 12 and 24 hours priming. GVI of landraces was improved by 40% following 12 hours of priming. GVI of hybrids was 11% and 7% slower than landraces after priming seeds for 12 and 24 hours, respectively. There was a highly significant interaction (P<0.001) between variety and priming for germination traits associated with vigour, namely root length, shoot length and fresh mass. For all varieties, priming seeds for 24 hours improved emergence at 25% FC, whereas priming for 12 hours improved emergence at 75% FC, albeit not significantly (P>0.05). There was a highly significant interaction (P<0.001) between priming and FC for MET. Priming seeds for 24 hours reduced MET for all varieties. Priming seeds for 12 and 24 hours increased leaf area by 33.8% and 29%, respectively. There was no correlation between the pool of soluble sugars and other measured parameters in response to priming, implying that benefits realised from priming were not related to availability of soluble sugars.

Hydropriming seeds for 12 and 24 hours, respectively, improved GVI, reduced MGT and improved emergence and MET of maize landraces under water stress. Performance of hybrid seeds remains superior to that of landraces even after seed treatment to improve germination and vigour. The positive response of landraces to seed treatment, and improved performance under water stress conditions, suggest that there is a need to identify genes for vigour in the landrace maize.

Keywords: Emergence, Germination, Hydropriming, Landraces, Water stress,

Abstract # 1144: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
COMPARATIVE PERFORMANCE OF TOMATO CULTIVARS IN A CLOSED SOILLESS HYDROPONIC PRODUCTION SYSTEM VERSUS AN OPEN BAG SYSTEM

Maboko, MM¹, Du Plooy, CP¹ and Bertling, I²

¹ARC Vegetable and Ornamental Plant Institute, P/Bag X293, Pretoria, 0001; ²Horticultural Science, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, Pietermaritzburg
Email: mmaboko@arc.agric.za

Keywords: Closed system, fruit cracking, open bag system, marketable yield

Abstract # 1166: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
INFLUENCE OF SEED PRIMING ON GERMINATION OF WILD CUCUMBER (CUCUMIS MYRIOCARPUS)

Mafeo, TP¹, Mashela, PW and Mphosi, MS

¹School of Agricultural and Environmental Sciences, University of Limpopo, Private Bag X1106, SOVENGA, 0727
Email: mafeot@ul.ac.za

Seeds of wild cucumber (Cucumis myriocarpus) germinate poorly due to an auto- allelochemical referred to as cucurbitacin A (Mafeo & Mashela, 2009). Consequently, this chemical must be leached by means of rain or irrigation water in order to enhance germination. The plant is being evaluated as an alternative crop since its leaves are widely used as greens, while extracts from its fruits have various medicinal and nematicidal properties (Mashela, 2002). An investigation was conducted to determine the germination of C. myriocarpus seeds in response to seed priming in stagnant and running water.

Treatments included an untreated control (T0) and priming of C. myriocarpus seeds in stagnant (T1) and in running tapwater (T2) for 24 hours. Primed seeds were placed in Petri dishes on moistened filter paper. The three treatments were arranged in a completely randomized design with 5 replicates per treatment, in growth chambers at 27°C and 80% RH. The filter papers were moistened daily at 17h00 using 2 ml distilled water, with germinated seeds being removed and recorded from each Petri dish daily for 10 days. The trial was terminated at 10 days once all T2 seeds had germinated.

Relative to untreated controls, priming in stagnant and running water improved cumulative germination by 48% and 83%, respectively. In T2, where auto-allelochemicals were leached out of the priming environment, germination rate was improved - with four peaks. In T1 and controls, the germination rate lagged behind T2 and had only two peaks. The presence of germination peaks suggests that germination in this species is staggered. As shown by the four peaks in T2, when the allelochemicals are leached the germination rate increases but the staggering is retained. This staggering probably serves as a survival strategy, ensuring that seeds do not germinate all at once when exposed to harsh environmental conditions.

Germination in C. myriocarpus, regardless of leaching of allelochemicals, is staggered as a survival strategy. The mechanism involved is not yet established. However, suppression of germination by Cucurbitacin A appears to be a common phenomenon on various seeds (Mafeo and Mashela, 2009). Future research will be focusing on the on the influence of cucurbitacin A on the activities of gibberillic acid on seed germination.

MAFEO, T.P. & MASHELA, P.W., 2009. Responses of Germination in Tomato, Watermelon and Butternut Squash to a Cucumis Bio-nematicide. J. Agric. Sci. (In Press).

Mashela, P.W., 2002. Ground wild cucumber fruits suppress densities of Meloidogyne incognita in tomato crop. Nematropica 32, 13 - 19.

The authors are grateful to the National Research Foundation for provision of funding.

Keywords: Allelochemicals, Cucumis myriocarpus, germination ,

Abstract # 1078: A Poster on Crop breeding & adaptation / Gewasveredeling & aanpassing
GENOTYPE BY ENVIRONMENT INTERACTION AMONG SELECTED SOYBEAN CULTIVARS FOR SEED YIELD AND NODULE FORMATION

Magagane, TG¹ and Shimelis, HA²

¹University of Limpopo, Department of Plant Production, P/Bag X1106, Sovenga 0727; ²University of KwaZulu-Natal, School of Agriculture and Agribusiness, African Center for Crop Improvement, P/Bag X01, Scottsville PMB 3209
Email: gordene@webmail.co.za

The nature and magnitude of the genotype by environment interaction is important to identify superior and stable genotypes under targeted environments (Hayward et al., 1993). This could assist in maximizing specific adaptation and to speed up the transfer of new cultivar to growers. The objective of this study was to determine yield stability of selected soybean (Glycine max L.) genotypes with suitable agronomic traits, high yield and active nodule formation.   

Field experiments were conducted under limited rainfall conditions (about 500 mm per year) during the 2007/2008 and 2008/2009 growing seasons at the University of Limpopo’s experimental farm (Syferkuil) and at farmer’s field at Gabaza community, Mopani District near Tzaneen. Ten selected soybean cultivars were field evaluated without inoculation using a randomized complete block design with three replications. Stability was assessed via joint regression analysis and superiority analysis.

Significant differences were found for genotypes, environments, and genotype by environment interactions. Stability analysis after Eberhart and Russell’s (1966) model suggested that the tested genotypes showed marked differences to environmental changes. The cultivar superiority measure for seed yield indicated that CLARK was the most stable genotype with an average seed yield of 5235 kg ha^-1, followed by ACCESSION 17 and BARC 17 with average seed yields of 4839 kg ha^-1 and 4582 kg ha^-1, respectively. In terms of number of nodules MAGOYE was identified to be stable with regards to number of nodules per plant followed by BARC 17.

Most of the genotypes performed better at Syferkuil than Gabaza. BARC 17 was selected as the most stable genotype for seed yield, nodule formation and other agronomical characters.

Eberhart, A. and W. Russell. 1966. Stability parameters for comparing varieties. Crop Science 6: 36 - 40.

Keywords: Glycine max, stability analysis, soybean ,

Abstract # 1140: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
THE EFFECT OF IRON SUPPLEMENTS ON THE POSTHARVEST CHILLING INJURY DISORDER OF AVOCADO FRUIT

Magwaza, LS¹ and Kruger, FJ¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: lembe@arc.agric.za

This presentation deals with recent research aimed at reducing chilling injury in South African avocado fruit. Previous surveys and trials have indicated that susceptibility to chilling injury may be associated with reduced fruit iron concentration (Magwaza et al., 2008). To substantiate these results, further trials were performed during 2007/08 season.

During the 2007/08 season, two experiments were executed. In the first, 90 grams of DDPA (Fe chelate) was top-dressed onto a ‘Hass’ orchard in the Kiepersol area. In the second trial, 60 grams DDPA split into 6 monthly dosages of 10 grams each, and applied by fertigation onto a ‘Pinkerton’ orchard in the Schagen area, starting from Sep. 2007 to Feb. 2008. Each treatment was replicated five times and each replicate consisted of seven trees. Fruit sampling for mineral analysis took place on a monthly basis from Dec. 2007 to Sep. 2008. Sampling for storage purposes in both trials was done on a bi-weekly basis from May to Sep. 2008. In the ‘Hass’ trial, a total of 15 fruit per replicate was harvested on each date of which five fruit were used for maturity and mineral content analysis and 10 were stored at phytosanitary temperatures (2°C for 28 days). In the case of ‘Pinkerton’, 67 fruit per replicate were sampled of which 60 were assigned to three postharvest storage temperatures (2, 4, and 6°C) and seven used for maturity and mineral analysis.

The results indicated that, on certain dates and at specific storage temperatures, the mean chilling injury scores were lower in fruit from orchards that received Fe supplements. However, in both cultivars, neither the flesh nor the skin iron content was increased by the iron treatments. Interestingly, the iron applications reduced the nitrogen content of the fruit at both experimental sites. This led to significant reductions in grey pulp, a nitrogen dependent internal physiological disorder of avocado fruit. On the other hand, the orchards became more susceptible to orchard freeze damage due the lower nitrogen status of the trees.

The Fe applications applied in the current study was found to influence the development of three physiological disorders of avocado fruit. Interesting observations were also made regarding the interaction between Fe supplementation and N uptake. However, taking all the above results into account, we conclude that, in contrast with elements such as nitrogen and calcium, it is not justified to attempt to modulate the fruit pulp Fe content in an attempt to improve the postharvest storage potential of the fruit. 

MAGWAZA, L.S., LEMMER, D., NTANDANE, J. & KRUGER, F.J., 2008. Effect of N and Fe fertilizer treatments on the incidence of chilling injury in ‘Fuerte’ and ‘Hass’ avocados. S. Afri. Avocado Growers’ Assoc. Yrbk. 3, 6-8.

The authors thank the South African Avocado Growers’ Association for financial support.

Keywords: Avocado, chilling injury, iron supplements, postharvest disorder

Abstract # 1141: A Poster on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
PRELIMINARY INVESTIGATION INTO THE CAUSES AND CONTROL OF ORCHARD COLD/FREEZE DAMAGE AND GREY SPECKLING IN SOUTH AFRICAN AVOCADO

Magwaza, LS¹ and Kruger, FJ¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: lembe@arc.agric.za

Keywords: Avocado, fruit physiological disorders, grey speckle, grey speckling, orchard cold/freeze damage,

Abstract # 1098: A Paper on Hort crop protection / Tuinbou gewasbeskerming
EFFICACY OF INSECTICIDES AGAINST THE POTATO TUBER MOTH (PHTHORIMAEA OPERCULELLA)

Majola, T¹, Visser, D¹ and Sambo, S¹

¹ARC Vegetable and Ornamental Plant Institute, P/Bag X293, Pretoria, 0001
Email: ThembisaM@arc.agric.za

The potato tuber moth is a non-indigenous pest that originated in South America and has been present in South Africa for more than a century (Visser 2009). It occurs wherever potatoes are cultivated, but is especially destructive under dry conditions in the warmer seasons. Potato farmers report contradictory “results” after using certain insecticides, and during some years the moth is a more severe problem than in previous years. Therefore, a study was initiated to test the efficacy of insecticides registered in against potato tuber moth field populations, compared to a known susceptible population.

Fourteen tuber moth populations were collected across and reared in an insectarium at the ARC-Roodeplaat for 2 – 3 generations. A detached-leaf bioassay technique was used to determine the survival of first instar larvae on treated leaves. The study involved three phases, i.e. a) using diagnostic dosages, b) using cumulative half dosages, and c) comparing results with a susceptible reference population.

All of the insecticides were equally effective against potato tuber moth at field recommended dosages, since they all caused 100% mortality of larvae after feeding on treated leaves for 9–12 days. Similar results were obtained for cumulative half dosages. When insecticides were used at 10% dosage the potato tuber moth populations showed limited mortality, which was similar to mortalities obtained with the control (no insecticide) and reference populations. 

The conclusion is that none of the insecticides currently registered against the potato tuber moth has lost their efficacy relating to tuber moth control when evaluating several populations collected across the country. Possible explanations for tuber moth “outbreaks” or unexplained poor control during some years will be discussed.

Keywords: bioassay technique, insecticides, potato tuber moth, infestation

Abstract # 1135: A Paper on Crop production / Gewasverbouing
EVALUATION AND SELECTION OF 20 SORGHUM [SORGHUM BICOLOR (L.) MOENCH] GENOTYPES FOR DROUGHT TOLERANCE: RESPONSE OF GRAIN YIELD, HARVEST INDEX AND 1000 SEED MASS TO DROUGHT STRESS

Malala, TJ¹, Soundy, P², Steyn, JM² and Wenzel, WG¹

¹ARC-Grain Crops Institute, P/Bag X1251, Potchefstroom 2520; ²Department of Plant Production and Soil Science, University of Pretoria, Pretoria 0002
Email: MalalaT@arc.agric.za

Sorghum bicolor (L.) is one of the major staple food cereal crops in Asia and Africa (Asante, 1995). Drought stress is one of the major environmental constraints for sorghum production throughout the world. To improve sorghum productivity in drought prone areas, plant response mechanisms should be well understood. The study was conducted to determine the effects of moisture stress on grain yield (GYLD), harvest index (HI) and 1000 seed mass (TSM).

Twenty sorghum genotypes were planted under dryland and irrigated conditions at density of 56 000 plants ha^-1 on sandy clay loam soil in Potchefstroom and sandy soil in Taung. The experiment was laid out in a randomised complete block design replicated three times. Drought stress was induced by withholding irrigation from five leaf stage to maturity to mimic naturally dryland farming conditions. Ten plants from 1.8 m² area of the two middle rows were harvested per plot at maturity and weighed. Heads were threshed and grains weighed to determine GYLD and TSM. Data analysis and correlation matrix were performed using GenStat statistical program.

HI and TSM should be considered in selection criteria because they significantly correlated with GYLD. Although drought susceptible index could separate tolerant genotypes from susceptible ones, it is not reliable criterion since it only considers genotypes exhibiting smaller yield reduction. Drought-tolerant genotypes should be chosen based on absolute yield under stress rather than yield reduction margin. Genotypes with high yielding and drought-tolerant potential should be selected.

ASANTE, S.A., 1995. Sorghum quality and utilization. African Crop Sci. J. 3(2), 231-40.

Funding from DAFF and AGRISETA is gratefully appreciated.

Keywords: Drought stress, drought tolerant, stress susceptibility index, yield potential

Abstract # 1114: A Paper on Crop production / Gewasverbouing
YIELD AND QUALITY RESPONSES OF TOMATO CULTIVARS UNDER ORGANIC FERTILIZATION USING FULLY DECOMPOSED CATTLE MANURE

Maleka, KG¹ and Shimelis, H²

¹University of Limpopo P/Bag X1106 Sovenga 0727; ²University of Kwazulu-Natal, School of Agriculture and Agribusiness, African Centre for Crop Improvement, P/Bag X01 Scottsville 3209, Pietermaritzburg
Email: malekakg@agric.limpopo.gov.za

Keywords: Limpopo, Lycopersicon esculentum, Tomato, Fruit size

Abstract # 1115: A Poster on Crop production / Gewasverbouing
CASSAVA FOR FOOD SECURITY: EVALUATION OF IMPROVED VARIETIES FOR SMALLHOLDER FARMERS IN MPUMALANGA

Mathews, C¹ and Allemann, J²

¹Department of Agriculture, P/Bag X11318, Nelspruit 1200, Mpumalanga; ²University of the Free State, PO Box 339, Bloemfontein 9300
Email: cherianm47@gmail.com

Keywords: smallholder farmers, SARRNET, Mpumalanga, Gari, Cyanogens,

Abstract # 1063: A Poster on Crop production / Gewasverbouing
DRY BEAN VARIETY EVALUATION IN THE LIMPOPO PROVINCE

Mathobo, R¹, Matlebjane, M.R and Maake , L.P

¹Limpopo Department of Agriculture Private Bag X9487 Polokwane 0700
Email: mathobor@agric.limpopo.gov.za

Dry bean is an important protein crop in South Africa grown mostly for human consumption. Of all the popular field crops grown in SA, dry beans have always commanded good producer prices relative to other crops. Beans in both their unprocessed and canned forms, constitute a vital, palatable and nourishing part of the diet of many people, particularly for those in the low income groups (DPO, 2006). Dry beans have the advantage over other legumes in that the seed can be stored for long periods of time without any serious loss of nutritional value. Limpopo is producing 8% of the total production of dry beans (DPO, 2006) in SA. Small scale farmers in the Limpopo Province have been producing dry beans since 2005. The objective of the study is to evaluate dry beans varieties for better performance in the Limpopo Province.

The trial was planted at two locations Nguvamuni project (30km outside Tzaneen) and Mamabolo village (31 km outside Polokwane). It is a randomized complete block design with five bean varieties (Jenny, Kranskop (control), Mkunzi, OPS-RS4 and Majuba) with four replications. It consisted of four 5m rows and between rows spacing of 90 cm. The data was collected from two middle rows and the other two were border rows.

Results showed that at Nguvamuni the grain yield of Kranskop was significantly different (P<0.05) from the other four varieties with the mean of 710 kg ha^-1. There was no significance difference between the other four varieties. At Mamabolo the grain yield of Kranskop (656 kg ha^-1) and OPS-RS4 (734 kg ha^-1) were significantly different (P<0.05) from that of Jenny, Majuba and Mkuzi. The interaction effect between variety and location was non- significant.

Results revealed that Kranskop was the best at Nguvamuni. At Mamabolo OPS-RS4 and Kranskop were the best. Follow up trials are planned to further research on the topic.

Dry bean producer’s organization (DPO), 2006. Production 2006. http://www.beans.co.za/ind3.htm

the farmers of the two localities are acknowledged for allowing us to use their land.

Keywords: drybeans, germination

Abstract # 1122: A Poster on Crop quality / Gewaskwaliteit
EVALUATION OF DRY WHITE BEAN (PHASEOLUS VULGARIS L) CULTIVARS FOR CANNING QUALITY

Matsela, T¹ and Chiremba, C¹

¹ARC-Grain Crops Institute, P/Bag X1251, Potchefstroom 2520
Email: matselat@arc.agric.za

Keywords: Dry Beans, Canning Quality, Phaseolus vulgaris L ,

Abstract # 1163: A Paper on Soil physics / Grondfisika
THE EFFECT OF RUNOFF STRIP WIDTH OF IN-FIELD RAINWATER HARVESTING ON MAIZE PRODUCTION UNDER VARYING SOIL WATER REGIMES

Mavimbela, SS¹ and Van Rensburg, L¹

¹University of the Free State, PO Box 339, Bloemfontein 9300
Email: sabelomavimbela@yahoo.com

Keywords: Water harvesting, runoff strip width, evaporation, transpiration, maize yield, water use efficiency

Abstract # 1067: A Poster on Crop production / Gewasverbouing
PLANT GROWTH AND PROLINE ACCUMULATION IN WILD MUSTARD GERMPLASM SUBJECTED TO WATER STRESS

Mbatha, TP¹ and Modi, AT¹

¹Crop Science Department, School of Agriculture and Agribusiness, Faculty of Science and Agriculture, UKZN, P/Bag X01, Scottsville PMB 3209
Email: 204502460@ukzn.ac.za

Keywords: Water Stress, Wild Mustard, Proline ,

Abstract # 1181: A Poster on Soil biology / Grondbiologie
MYCORRHIZAL ROOT COLONISATION AND MICROBIAL ENZYME ACTIVITY AS AFFECTED BY DIFFERENT SOIL CULTIVATION PRACTICES IN AN APPLE ORCHARD SOIL

Meyer, AH¹, Dames, J² and Wooldridge, J¹

¹ARC Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch 7599; ²Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6139
Email: meyera@arc.agric.za

Keywords: chemical control, microbial community, AM, mulch, apple, enzyme

Abstract # 1187: A Poster on Soil biology / Grondbiologie
AN ASSESSMENT OF ARBUSCULAR MYCORRHIZAL (AM) FUNGI IN APPLE ORCHARDS OF THE WESTERN CAPE: A PRELIMINARY INVESTIGATION

Meyer, AH¹, Dames, J² and Wooldridge, J¹

¹ARC Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch 7599; ²Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6139
Email: meyera@arc.agric.za

Keywords: AM, orchard, conventional, glomalin, spore, survey

Abstract # 1191: A Poster on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
POSTHARVEST EVALUATION OF NEW MANDARIN CULTIVARS

Mhlophe, SD¹ and Kruger, FJ

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: sibongile@arc.agric.za

‘Valley Gold’ and ‘African Sunset’ are promising new mandarin selections from the ARC’s breeding programme. In order to be marketable, the fruit must be able to withstand the rigors of postharvest handling and reach the consumer in good condition. Thus, it is crucial that the postharvest characteristics of these new cultivars be evaluated, to ensure that they meet the aforementioned criteria and are of commercial appeal to the consumer. To achieve this, the fruit quality and postharvest performance of these new cultivars was tested against a commercial cultivar, ‘Afoura’. 

The trial was conducted in the post-harvest laboratory of the ARC-ITSC experimental farm in Nelspruit. New cultivars ‘Valley Gold’ and ‘African Sunset’ were evaluated and compared to a commercial cultivar, ‘Afoura’. The following treatments were performed on each cultivar:

1.      5 days preconditioning @ 2°C followed by 35 days storage at 5°C

2.      5 days preconditioning @ 2°C followed by 16 days cold sterilisation @ 2°C and 19 days storage @ 5°C

3.      5 days preconditioning @ 10-15°C followed by 35 days storage at 5°C

4.      5 days preconditioning @ 10-15°C followed by 16 days cold sterilisation @ 2°C and 19 days storage @ 5°C

Samples were kept in cold storage for a period of 35 days. Evaluations included firmness, soluble solids content (SSC), titratable acidity (TA), chilling injury (CI) and pathological disorders. For consumer acceptance (i.e. peelability, firmness, appearance and taste), the fruit was evaluated by 18 — 20 untrained panelists using a 9-point Hedonic scale (9 = like extremely, 5 = neither like nor dislike, 1 = dislike extremely).  

The results showed that the different cold treatments and storage temperatures did not affect the sugar content of mandarins. All ‘African Sunset’ and ‘Valley Gold’ fruit preconditioned at 2^oC had a significantly higher organic acid content than those preconditioned at 10^oC. Preconditioning at low temperatures (2^oC) followed by storage at low temperatures resulted in better organic acid retention with no CI observed. The effects of preconditioning treatments on the TA and Firmness values were only slight, although significant. ‘African Sunset’ and ‘Valley Gold’  flavour and texture were positively affected, as reflected by the results of the sensory evaluation. Based on the sensory evaluation results, it was deduced that consumers preferred the new mandarin cultivars, ‘African Sunset’ and ‘Valley Gold’ to ‘Afoura’.

Results indicated that the new cultivars ‘African Sunset’ and ‘Valley Gold’ have good storage qualities and may perform better than ‘Afoura’ as commercial cultivars, when treated and stored under commercial conditions.

Keywords: Mandarin, Valley Gold, African sunset, cold storage, postharvest,

Abstract # 1175: A Paper on Soil fertility / Grondvrugbaarheid
RESPONSE OF AMARANTHUS TRICOLOR, CLEOME GYNANDRA AND BRASSICA RAPA TO FERTILIZER APPLICATION

Modisane, PC¹, Beletse, YG¹ and Du Plooy, CP¹

¹Agricultural Research Council (ARC) - Roodeplaat, Vegetable and Ornamental Plant Institute (VOPI), P/Bag X293, Pretoria 0001
Email: pmodisane@arc.agric.za

Keywords: Amaranthus, Cleome, Brassica, yield, fertilization,

Abstract # 1119: A Paper on Crop production / Gewasverbouing
SEED PERFORMANCE AND WATER STRESS TOLERANCE OF LOCAL BAMBARA GROUNDNUT GERMPLASM

Modi, AT¹, Gilbert, DL¹ and Tesfay, SZ¹

¹Agricultural Plant Sciences, School of Agricultural Sciences & Agribusiness, University of KwaZulu-Natal, P/Bag X01, Scottsville PMB 3209
Email: modiat@ukzn.ac.za

Keywords: Germination, seed, temperature, water stress

Abstract # 1170: A Paper on Crop production / Gewasverbouing
WATER USE EFFICIENCY OF FOUR AFRICAN LEAFY VEGETABLES

Mogotlane, ID¹, Beletse, YG¹ and Du Plooy , CP¹

¹Agricultural Research Council - Roodeplaat Vegetable and Ornamental Plant Institute, P/Bag X293, Pretoria 0001, South Africa
Email: mogotlane@arc.agric.za

African Leafy Vegetables (ALV’s) are important new crops with a potential to broaden food base in South Africa.   An understanding of their water use is essential for evaluating their potential to grow in areas where water is a limiting factor. The objective of this study was to investigate the water use efficiency of Chinese cabbage, amaranthus, corchorus and cowpea.

Water use efficiency trial was carried out in 2007 and 2008 growing seasons at the ARC-Roodeplaat ARC-VOPI, 40 km North East of Pretoria. The trial was conducted under a rain shelter that has a total experimental area of 288 m². Four irrigation water treatments with three replications were laid in a randomized complete block design. The treatments applied were irrigation to field capacity (FC), described as 100FC, 75% of the water applied to refill to FC (75FC), 50% of the water applied to refill to FC (50FC) and 25% of the water applied to refill to FC (25FC).  Plant samples were collected every 10 – 14 days and partitioned into leaf, stem, root, and flower to determine the growth of the plant. Data were subjected to analysis of variance using General linear model procedure of SAS version 8.0 (SAS Institute Inc. 1999).

Chinese cabbage and amaranth showed a yield reduction of 16-35% when receiving 25-50% of 100FC, whereas cowpea showed a yield reduction of 40-50%. Corchorus receiving 25-50% showed a yield reduction of 25-29%. In all experiments, higher water productivity (WP) was obtained in crops receiving 25FC treatment, as compared to crops receiving 100FC irrigation treatment.  All crops receiving less irrigation treatment (25FC) resulted in lower yields, as compared to the well irrigated crops (100FC), implying that increasing soil water content could lead to increased yields. Higher WP, however, was obtained with the dry irrigation treatments (25FC), as compared to the full irrigation treatments (100FC), indicating that optimum yield of the four crops could be attained in areas where water is a limiting factor if proper crop and deficit irrigation management is practiced.

The yield differences of amaranths, cowpea and corchorus obtained from the different irrigation treatments applied were negligible, and this could be an indication of their tolerance to water stress. The WP’s obtained from this preliminary experiment is optimal with the low irrigation treatments (25FC); however, further investigation is needed in order to use these results in the recommendation of guidelines of cropping systems at national level.

Water Research Commission for funding

SAS Institute Inc. (1999) User’s guide, version 8.0 (5^th Edn, Vol 2). Cary, NC, USA

Keywords: Water use, water productivity, food crops, African leafy vegetables, yield , evapotranspiration

Abstract # 1112: A Paper on Crop production / Gewasverbouing
EVALUATION OF NITROGEN LEVELS AND PLANTING DATES ON COTTON CULTIVARS (GOSSYPIUM SPP.) IN THE EASTERN CAPE PROVINCE, SOUTH AFRICA

Mokoena, ML¹, Eulitz, E¹ and van Biljon, ER¹

¹Agricultural Research Council, Institute for Industrial Crops, P/Bag X82075, Rustenburg, 0300, South Africa
Email: mpolom@arc.agric.za

A study was conducted at Addo and Cradock for three consecutive seasons between 2004/2005 and 2006/2007. Cotton was introduced to this province as one of the cash crop to try and help in improving rural livelihood. The main objective was to determine nutrient uptake of cotton plants and their response to different nitrogen fertilizer levels on seed cotton yield and fibre quality.

Three different nitrogen levels (80, 120 & 160 kg N/ha) and a control (0 kg N/ha) together with four different cotton cultivars (NuOPAL, Delta OPAL, Delta OPAL RR, DP404B) were evaluated on a split plot design. The nitrogen fertilizer treatments were applied as split applications at 4, 8 and 12 weeks after planting with supplemental sprinkler irrigation. Main effects were nitrogen application and sub effects were cultivars.

Significant differences were found in the yields of different cultivars and planting dates at different nitrogen fertilization levels. Highest yields that ranged from 4.1 to 5.3 kg/ha seed cotton were obtained at Addo from the early planting across the treatments as compared to late planting. The untreated control gave the lowest yield in both localiting with the two planting dates. At 80 and 120 kg/ha N of nitrogen levels NuOPAL gave the high yields of 4325 and 4143 kg/ha on early planting at Addo, respectively. Where 160 kg/ha N was applied, highest yield of 5312 kg/ha seed cotton were obtained by NuOPAL at Addo with early planting. Even though there were no significant differences between treatments interaction, highest yields were observed from 80 kg/ha to 120 kg/ha N level at early planting across cultivars at Addo, whereas at late planting yields were very low across N-treatment and cultivars.

At Cradock,yields were generally low across all treatments, at early October planting NuOPAL gave better yields of between 2999 and 1989 kg/ha seed cotton at 120 kgN/ha and 160kgN/ha respectively, as compared to other cultivars.  NuOPAL gave the highest yield and yield characteristics than the DeltaOPAL, DP404B and DeltaOPAL RR cultivars in both localities. It has also been shown from fibre quality analysis results that fibre properties were within the norms of good fibre quality.

The results have shown that cotton can grow well in some areas of the Eastern Cape only when planted from early to middle October. It had been noted that cotton planted during late October are prone to early cold or frost, insects and pests damaged at the end of the season thereby reducing yields. Good yields obtained at 80 and 120 kg N/ha are a clear indication that, these nitrogen levels could be optimum and the cost could be reasonable for the farmers and this will be beneficial in terms of saving on inputs. NuOPAL is the best cultivars for the area owing to its better yield and tolerance of the above mentioned yield reducing factors.

Keywords: Nitrogen fertilization, cotton cultivars, planting dates ,

Abstract # 1061: A Paper on Soil fertility / Grondvrugbaarheid
PRECISION MANURE MANAGEMENT ACROSS SITE-SPECIFIC MANAGEMENT ZONES: SURFACE SOIL AND ENVIRONMENT QUALITY

Moshia, ME¹ and Khosla, R²

¹University of Limpopo (Turfloop Campus), School of Agric & Env. Sciences, P/Bag X1106, Sovenga 0727; ²1170 Campus Delivery, Dept. of Soil and Crop Sciences, Fort Collins, CO, 80523, USA
Email: moshia@rams.colostate.edu

Keywords: Environmental quality, soil quality, water quality, precision agriculture, management zones,

Abstract # 1178: A Poster on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
SOIL CLASSIFICATION FIELD PRACTICAL: PARADIGMS, PERSPECTIVES AND SOCIAL LEARNING THEORIES

Moshia, ME¹, Motsoeneng, TJ¹, Kanyane, PM¹ and Madiba, OF¹

¹Dept. of Soil Science and Remote Sensing, University of Limpopo (Turfloop), P/Bag X 1106, Sovenga 0727
Email: moshia@rams.colostate.edu

Keywords: paradigms and perspectives, social learning theory, soil classification, field practical, visual learning,

Abstract # 1167: A Paper on Crop protection / Gewasbeskerming
COMPARING TOXICITIES OF CUCUMIN BIO-NEMATICIDE AND SYNTHETIC NEMATICIDES

Mphosi, MS¹, Mafeo, TP¹ and Mashela, PW¹

¹School of Agricultural and Environmental Sciences, University of Limpopo, P/Bag X1106, SOVENGA 0727, South Africa
Email: mphosim@ul.ac.za

INTRODUCTION

Extracts of wild cucumber (Cucumis myriocarpus) fruits consistently suppressed numbers of the root-knot (Meloidogyne incognita) in vegetables such as tomotatoes, butternuts and pepper.  The bionematicide is widely used in nature farming in Limpopo Province. The material also suppress numbers of the citrus nematodes.The active ingredient in this bio-nematicide had been identified as cucurbitacin A, which is chemically referred to as cucumin. Relative acute toxicity is measured in terms of LD50 for the Lethal Dosage required to kill 50% of a test organism. The higher the LD50, the less acutely toxic the product is. After determining the toxicity of cucumin, a desktop study was conducted to determine the relative toxicity of this material to standard synthetic nematicides.

MATERIALS AND METHODS

The study was conducted at the University of Limpopo, Agrofood Technology Station Laboratory. The LD50 of cucumin was compared with the LD50 of three Carbamates, three Organophosphates and one bio-nematicide, which are widely used as nematicides in suppression of plant parasitic nematodes. Comparisons were made by dividing the LD50 of selected nematicides by that of Cucumin.

RESULTS AND DISCUSSION

On average, Cucumin was 11.5 (range1.8 – 22) more toxic than the Carbamates, 47.7 (range 4 – 123) more toxic than the Organophosphates, and 384 more toxic than Crop Guard. This observation, confirms assertions that cucumin might be the most toxic chemical. The efficacy, toxicity and lifespan of a nematicide depend on the soil type.  Cucumin breaks into two compounds which were also shown to have high bioactivity. More work still needs to be done to provide information about the end product of this highly toxic bio-nematicide in the environment.

These variables have not been determined for cucumin as a bio-nematicide.  

CONCLUSION

Currently, various studies are underway to determine the efficacy, toxicity and lifespan of cucumin as a bio-nematicide under various soil conditions.

ACKNOWLEDGEMENTS

The authors are grateful to Tshumisano for provision of funding.

Keywords: Bio-nematicide, Cucumin, Cucumis myriocarpus ,

Abstract # 1177: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
EFFECT OF SPACING, TRANSPLANTING TIME AND HARVESTING METHODS ON AMARANTHS (AMARANTHUS CRUENTUS) PRODUCTION

Mulandana, NS¹, Beletse , YG, Du Plooy, CP and Mamadi, NE

¹ARC Vegetable and Ornamental Plant Institute, P/Bag X293, Pretoria, 0001
Email: SMulandana@arc.agric.za

Vegetable amaranths (Amaranthus cruentus) is one of the popular indigenous vegetables in the Republic of South Africa. It is an annual, fast growing plant, and is a rich source of calcium, iron, and vitamins A and C. Compared to exotic vegetables, amaranths have received minimal research and development attention that limited its potential as a food crop. The aim of this study was to determine the optimum spacing, transplanting time and harvesting methods of amaranths.

Two experiments were carried out at ARC - Roodeplaat, VOPI, Pretoria, in summer 2008: effect of spacing and harvesting methods, and optimum transplanting time of amaranths. The experimental design for the optimum spacing and harvesting methods was in a randomized complete block design, with six different spacings and two harvesting methods, replicated three times. The spacings were 10 x 20 cm (50 plants m^-2) (S1), 20 x 20 cm (25 plants m^-2) (S2), 10 x 50 cm (20 plants m^-2) (S3), 20 x 50 cm (10 plants m^-2) (S4), 10 x 75 cm (13 plants m^-2) (S5) and 20 x 75 cm (S6) (6 plants m^-2). The harvesting methods evaluated were tipping (H1) and cutting to 30 cm height (H2) and the optimum transplanting time (Tp) was determined by using 4 transplanting dates (Tp1, Tp2, Tp3, and Tp4). All these treatments included tipped (removing the growth shoot before planting) (Tp1T, Tp2T, Tp3T, Tp4T) and not tipped (Tp1NT, Tp2NT, Tp3NT, Tp4NT). The experiments were repeated from October 2009 to December 2009.

The first year results showed that the highest yield was obtained by the wider spacing and there was no significant difference between the two harvesting methods. The highest total fresh mass and good quality amaranths yield was obtained from Tp2 and Tp3. The yield potential of amaranths was higher at early transplanting than later transplanting and higher at closer spacings than at the wider spacings. The combined results for both years will be presented.    

From the first year’s results it was concluded that the yield of amaranths can be significantly increased by transplanting the seedlings when they are 21 to 28 days old at a spacing of 20 x 20 cm (25 plants m^-2), which is commonly used by farmers. The harvesting method did not show any significant difference between the treatments.

The authors would like to acknowledge the Department of Science and Technology (DST) for funding the project.

Keywords: Amaranths, Indigenous vegetables, seedlings, food crops

Abstract # 1100: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
THE EFFECT OF 2,4-D ON FRUIT SPLITTING AND FRUIT QUALITY OF ‘MARISOL’ CLEMENTINE MANDARIN

Mupambi, G¹ and Verreynne, JS²

¹Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602; ²Citrus Research International, Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602
Email: 15423212@sun.ac.za

Fruit splitting is a physiological disorder in citrus that develops as a result of cracking of the rind, usually from the stylar end of the fruit. It occurs in most citrus types but is more widespread amongst the thin peeled mandarin cultivars and, to some extent, in navel oranges. Under South African conditions 30% split fruit is common in mandarins, sometimes reaching up to 45%. Affected fruit usually drops during the last two to three months before fruit maturity, resulting in yield loss.

The study was conducted on ‘Marisol’ Clementine mandarin trees grafted on Troyer citrange rootstock. Treatments included an untreated control, 2,4-D applied at 15 mg∙L^-1 or 25 mg∙L^-1 at full bloom (FB) and 15 mg∙L^-1 or 25 mg∙L^-1  at 100% petal drop (PD). Split fruit were removed from the trees and counted every two weeks from mid-March until harvest in early May. At harvest a sample of 12 fruit per tree was collected to determine internal and external fruit quality.

The application of 2,4-D significantly reduced the total number of split fruit collected in all treatments except 15 mg∙L^-1 at FB. Internal fruit quality was not affected by 2,4-D application.  Externally, the fruit colour and the fruit shape were not affected. However, treated fruit had coarser rinds due to enlarged oil glands and the styles persisted on the treated fruit until fruit maturity.

Although 2,4-D reduced fruit splitting in this study, it cannot be recommended at the concentrations used. Future work should include the use of lower concentrations of 2,4-D to attempt to reduce the coarse rinds with enlarged oil glands.

Keywords: Citrus reticulata, external quality, fruit splitting , internal quality , rind coarseness,

Abstract # 1174: A Paper on Agrometeorology / Agrometeorologie
RAINFALL RISK ANALYSIS FOR RAINFED AGRICULTURE IN THE LIMPOPO BASIN

Mupangwa, W¹

¹ICRISAT-Zimbabwe, Matopos Research Station, Bulawayo, Zimbabwe
Email: mupangwa@yahoo.com

Keywords: Limpopo basin, rainfed agriculture, risk, dry spell

Abstract # 1203: A Poster on Hort physiology / Tuinboufisiologie
EVALUATING THE EFFECT OF MOISTURE STRESS ON TOMATO PLANTS USING REMOTE SENSING TECHNIQUES

Mushia, N¹, Shaker, P¹ and Shimelis, HA²

¹School of Agricultural and Environmental Sciences, University of Limpopo, P/Bag X1106, Sovenga, 0727, South Africa; ²African Centre for Crop Improvement, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa
Email: NMMushia@gmail.com

Crop water stress has a major effect on crop production, yield and crop health. It is because of this effect that rapid, low-cost techniques are required to monitor and evaluate moisture stress. While many field-based techniques have proved suitable, they have sometimes proved problematic in application over large areas of land (Dreyer, 1990). For this reason remote sensing technology in the form of Normalized Differential Vegetation Index (NDVI) data by Green Seeker sensor and a thermal infrared thermometer, as well as agronomic traits were used to evaluate moisture stress on tomato plants.

Non-stressed plants received 500ml of water daily, while stressed plants received 500ml of water every 3 days. Canopy temperature was measured using an infrared thermometer, NDVI values were recorded using a green seeker hand-held optical sensor unit and stomatal conductance was determined using a leaf porometer. The data was collected in the morning from 9:00 to 11:00 and in the afternoon from 13:00 to 15:00. Other agronomic traits, including days taken for 50% flowering, plant height, number of fruits per plant and fruit yield per plant were recorded.

RESULTS AND DISCUSSION

Leaf temperature in stressed plants was high compared with non-stressed plants under both greenhouse and field conditions, which confirms the findings of Jackson (1982), whereas NDVI and stomatal conductance values were low. Number of fruits per stressed plant was low, with 4 fruits per plant under field conditions and 5 fruits per plant under greenhouse conditions, compared with 9 fruits per plant under field conditions and 13 fruits per plant under greenhouse conditions for non-stressed plants.

The experiment showed that it is possible to evaluate the effect of moisture stress on tomato plants by the use of canopy temperature, NDVI, stomatal conductance and agronomic traits. Infrared thermometer measurements, a remote sensing technique, clearly detected canopy temperature increases that occurred as a result of a reduction in transpiration.as plants became stressed

JACKSON, R.D., 1982. Canopy temperature and crop water stress. p. 43-85. In: D. Hillel (Ed.). Advances in Irrigation. Academic Press, New York.

Keywords: NDVI, Stomatal conductance, canopy temperature, remote sensing, greenhouse,

Abstract # 1077: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
THE EFFECT OF SUBSTRATE PH VALUE ON MYCELIUM GROWTH SPEED OF MUSHROOM STRAINS: PLEUROTUS OSTREATU, AURICULARIA POLYTRICHA, LENTUNUS EDODES AND GANOMERDA LUCIDIUM

Mzini, LL¹ and Lin, Z²

¹Dohne Agricultural Development Institute, Department of Agriculture, P/Bag X15, Stutterheim, 4930; ²JUNCAO Research Institute, Fujian Agriculture and Forestry University, People’s Republic of China
Email: loyisomzini@yahoo.com

Keywords: pH, mycelial growth, mushroom strains, substrate

Abstract # 1169: A Poster on Weeds, crops and herbicides / Onkruide, gewasse en onkruiddoders
INVESTIGATING THE ROLE OF MANGANESE IN GLYPHOSATE SUSCEPTIBILITY OF TWO RYEGRASS (LOLIUM SPP.) POPULATIONS BY MEANS OF A PETRI DISH METHOD

Ncedana, C¹ and Pieterse, PJ¹

¹Department of Agronomy, P/Bag X1, Matieland 7602
Email: 15255352@sun.ac.za

Keywords: Glyphosate, Lolium, Manganese ,

Abstract # 1157: A Poster on Weed management / Onkruidbestuur
INTERACTION OF HERBICIDE CHOICE AND RATE BASED ON WEED SPECIES AND DENSITY

Ndou, AM¹ and Dille, JA²

¹ARC-Roodeplaat (VOPI), P/Bag x293, Pretoria 0001; ²Kansas State University, Department of Agronomy, Throckmorton Plant Science Center, MANHATTAN KS, 66506
Email: NdouM@arc.agric.za

Keywords: Weed density, herbicide rate, herbicide choice ,

Abstract # 1158: A Paper on Weed management / Onkruidbestuur
WEED EMERGENCE PATTERNS IN SOYBEAN AS AFFECTED BY MANAGEMENT PRACTICES

Ndou, AM¹ and Dille, JA²

¹ARC-Roodeplaat (VOPI), P/Bag x293, PRETORIA 0001; ²Kansas State University, Department of Agronomy, Throckmorton Plant Science Center, MANHATTAN KS, 66506
Email: NdouM@arc.agric.za

Keywords: Management Practices, weed patch, weed emergence pattern ,

Abstract # 1198: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
TOTAL PHENOLICS AND ANTIOXIDANT ACTIVITY OF BLACK TEA AS A FUNCTION OF BREWING TEMPERATURE AND TIME

Negukhula, S¹, Mariga, IK and Mudau, FN

¹Department of Plant Production, School of Agricultural and Environmental Sciences, University of Limpopo, P/Bag X1106, Sovenga, 0727
Email: 200818248@ul.ac.za

Potential health benefits of tea, together with its popularity as a beverage, have prompted numerous investigations of the chemical constituents of tea and their antimutagenic (Halder et al., 2005), anticarcinogenic and antioxidant (Han, 1997; Sarkar et al., 2001) properties.

MATERIALS AND METHODS

Black tea obtained from Mukumbani Tea Estate was brewed using a water bath at 30°C, 60°C or 90°C for either 3 or 10 minutes. The Folin Ciocalteau method (Waterman & Mole, 1994) was used to determine total phenols in the black tea extract. Antioxidant activity was determined using the Trolox Equivalent Antioxidant Capacity (TEAC) assay (Awika & Rooney, 2004). The Vanillin HCL method (Prince et al., 1978) was used to determine tannins. There were three replicates, with each measurement made in duplicate. Data was subjected to analysis of variance (using SAS, 2003) General Linear Model procedure, and the Duncan Least Significant Difference test was used to identify differences among the means.

RESULTS AND DISCUSSION

Total polyphenols, antioxidant activity and tannin content decreased with decreasing temperature and time. At 90°C for 3 minutes 7.68 mg/100g total polyphenol, 3.85 μmol/g of antioxidants and 2.81 mg/100g of tannin were extracted. This decreased to 5.50 mg/100mg total polyphenols, 1.31 μmol/g of antioxidants and 0.72 mg/100mg of tannin at 30°C for 10 minutes.

Black tea brewed at 90°C for 3 minutes contains higher levels of polyphenol and optimum total antioxidant activity. The use of lukewarm water to brew black tea must be discouraged.

AWIKA, J.M. & ROONEY, L.W., 2004. Sorghum photochemical and their stability in sunflower oil and emulsion. Food Chem. 64, 323-329.

HALDER, B., PRAMANICK, S., MUKHOPADHYOY, S. & GIRI, A.K., 2005. Inhibition of benzo[a]pyrene induced mutagenecity and genotoxicity multiple test systems. Food Chem. Toxicol. 43, 591-597.

HAN, C., 1997. Screening of Anticarcinogenic ingredients in Tea polyphenols. Cancer Lett. 114, 153-158.           

PRINCE, M.L., VAN SCOYOC, S. & BUTLER, L.G., 1978. A critical evaluation of the vanillin reaction as an assay for tannin in sorghum grain. J.Agr. Food Chem. 26, 1214-1218.

SARKAR, A. & BHADURI, A., 2001. Black tea is powerful Chemopreventor of reactive oxygen and nitrogen species: comparison with its individual Catechin constituents and Green tea. Biochem. Bioph. Res. Co. 284(1), 173-178.

WATERMAN, P.G. & MOLE, S., 1994. Analysis of Plant Metabolites. Alden Press Limited, Oxford. p. 1-16, 66-103.

The authors would like to thank Tshumisano for providing funds.

Keywords: Total phenols, Antioxidant activity

Abstract # 1108: A Paper on Crop production / Gewasverbouing
YIELD OF IRRIGATED WINTER AND SUMMER GRAIN CROPS AS AFFECTED BY CROP ROTATION

Nel, AA¹

¹ARC-Grain Crops Institute Private bag X1251 Potchefstroom 2520
Email: nela@arc.agric.za

Yield improvement through crop rotation under dry-land conditions on the Highveld has been proven through research. Benefits of sound crop rotation systems are the improvement of profits and the reduction of production risk. The rate of cropping under irrigation is doubled to two crops every 12 months, which might make rotation even more important than under dry-land. This experiment was initiated to determine the importance of crop rotation under irrigation on a sandy soil at Vaalharts where two crops are grown annually.

MATERIALS AND METHODS

A field trial under flood irrigation with the following crop rotation systems was conducted over a period of 4.5 years on the Vaalharts experimental farm at Jan Kempdorp:1. Canola – maize; 2. Wheat – maize; 3. Barley – maize; 4. Canola – groundnut; 5. Wheat – groundnut; 6. Barley – groundnut; 7. Canola - maize - wheat – maize; 8. Canola - groundnut - wheat – maize; 9. Canola - groundnut - wheat – groundnut; 10. Canola - soybean - wheat – groundnut. A complete randomised block design with four replicates were used, the results analised through an analysis of variance with significance at p = 0.05. Agronomical practices were according to best practice recommendations.

RESULTS AND DISCUSSION

Cropping system had a significant effect on the yield (p = 0.05) of maize (mean yield 10 102 kg ha^-1). The yield of maize in the canola-maize one-year system was 18 % lower, and that of maize following canola in the in the canola - maize - wheat - maize system, 12 % lower than that of maize in the canola-groundnut-wheat-maize system. The yield of maize in the one-year wheat-maize system was 9 % lower than that of maize in the two-year systems where canola and groundnuts were also part of the cropping sequence. Groundnut yield (mean 3 991 kg ha^-1) was affected by crop rotation system. As in the case of maize, groundnuts grown in the most crop diverse rotation system had the highest yield. The yield of groundnut following canola was 14 % and 9% lower than the yield of groundnut preceded by wheat and barley, respectively. The yield of canola was dominated by a seasonal effect but also influenced by an interaction between seasons and cropping systems. The annual canola yield among crop systems varied from 872 to 3 142 kg ha^-1. Barley, with a mean yield of 6311 kg ha^-1 was not affected by crop rotation, but by seasons only. Wheat (mean yield 5983 kg ha^-1) was affected by a crop system x season interaction.

Crop rotation under irrigation affected the grain yield of (in declining order of sensitivity) maize, groundnut, wheat, canola. Barley was not affected by crop rotation.

Financial support from the Protein Research Foundation and Winter Cereal Trust is acknowledged.

Keywords: Barley, canola, crop rotation, groundnut, maize, wheat

Abstract # 1151: A Poster on Crop production / Gewasverbouing
THE EFFECT OF NITROGEN FERTILIZER, PLANTING DENSITY, AND VARIETY IN MAIZE YIELD AT LWAMONDO, LIMPOPO PROVINCE

Nemutshili, VZ¹ and Ogola, JBO²

¹Dept of Agriculture, Limpopo Province, P/Bag X9847, Polokwane 0700; ²Dept of Plant Production, University of Venda, P/Bag X5050, Thohoyandou 0950
Email: nemutshiliv@agric.limpopo.gov.za

Keywords: Nitrogen fertilizer, planting density, maize variety, maize yield

Abstract # 1125: A Poster on Crop production / Gewasverbouing
ASSESSMENT OF PIGEON PEA (CAJANUS CAJAN L.) –BASED INTERCROPPING SYSTEM WITH MAIZE

Ngobeni, ND¹

¹Private Bag X 82075, Rustenburg,0300
Email: ntsakon@arc.agric.za

INTRODUCTION: Pigeon pea (Cajanus cajan) is one of the newly introduced crops in South Africa. It had been known in some African countries like , Malawi, Tanzania and  Mozambique as a cash crop for a number of years.  Pigeon peas had be grown successfully under dryland conditions as a mono crop with low production inputs, Pigeon peas is a legume crop, its roots nodules enrich the soil by adding about 40kg of nitrogen per hectare back to the soil. After harvesting the pods for human consumption, it can be used as a fodder for feeding animals. The pods contain about 19-28% protein.

Adrylandpigeon pea based intercrop trial was established during 2008/2009 at the Agricultural Research Council Experimental farm Rustenburg North-West Province to assess the compatibility and intercropping advantages of non Inoculated pigeon pea and maize. Trial design was randomized complete block design (RCBD) in factorial consisting of two pigeon pea cultivar (ICEAP 00360 and ICPL 87091), two open pollinated maize Variety (Zim 423 and Zim 523), and three intercropping intervals( Simultaneously planted intercrop; maize planted 20 DAP and 30 DAP of pigeon pea) and included are two monocropping of Maize and pigeon pea. Treatments were replicated 4 times. Parameters measured Maize Grain, pigeon pea grain yield, pod yield and land equivalent ratio (LER) was computed. Data collected was analyzed using Genstat 3.5 while means were separated using least significant different (LSD) at P≤ 0.05.  

Grain yield of maize cultivars was significantly different between intercropping interval and maize cultivars. Maize grain yields were high when maize was planted simultaneous with pigeon peas, this accounted for 6719 kg ha^-1 grain yield, Maize grain yields were lower when planted 20 days after pigeon peas but better than when planted 30 days after pigeon peas. ZIM 523 had good grain yields across intercropping intervals dates as compared to ZIM 423. Pod yield (Pods before thrashing) also varied between intercropping interval and pigeon pea cultivars, thus pod yield was high in the 20DAP intercropping, followed by the 30 DAP intercropping. Pod yields were lower at simultaneously planted intercrops compared to when intercropped at 20DAP and 30DAP. Cultivar ICEAP 00360 yielded best in intercropping compared to ICPL 87091.Pigeon grain yield differed significantly between intercropping interval and cultivars. Higher yields were observed when pigeon pea was intercropped at 20 DAP. Land equivalent ratio revealed intercrop advantage with a ratios ranging from of up to 1.9 except for when pigeon pea was intercropped at 30DAP with cultivar ICEAP 00360 which was lower than 1.

Pigeon peas seem to be compatible with all maize cultivars intercropping, especially when maize is brought in the system 20 DAP of pigeon peas. It was observed that simultaneous intercropping of these crops favours maize yield while it suppress pigeon pea yield. Intercropping at 30 DAP reduce yield of both crops. Generally the ratios have shown intercrop advantage.

Keywords: Pigeon peas, maize, intercropping intervals ,

Abstract # 1188: A Paper on Crop nutrition & water / Gewasvoeding & water
GROWTH AND YIELD RESPONSE OF CASSAVA, MANIHOT ESCULENTA CRANTZ TO ORGANIC AND INORGANIC FERTILIZER

Ngobeni, ND¹ and Buthelezi, NM¹

¹Agricultural Research Council, P/Bag X82075, Rustenburg 0300
Email: ntsakon@arc.agric.za

Keywords: Cassava cultivars, yield response, inorganic fertilizer ,

Abstract # 1136: A Poster on Weeds, crops and herbicides / Onkruide, gewasse en onkruiddoders
THE INFLUENCE OF VARIOUS ADJUVANTS ON BIPYRIDYLIUM HERBICIDE EFFICACY

Nienaber, H¹

¹ARC-Small Grain Institute, P/Bag X29, Bethlehem 9700
Email: deweth@arc.agric.za

Keywords: adjuvants, bipyridyliums, herbicide efficacy ,

Abstract # 1118: A Poster on Agrometeorology / Agrometeorologie
EVAPORATION ESTIMATION USING A TEMPERATURE VARIANCE METHOD ABOVE SUGARCANE

Nile, ES¹ and Savage, MJ¹

¹University of KwaZulu-Natal, P/Bag X01, 3209 Scottsville
Email: 206525249@ukzn.ac.za

Keywords: Sensible heat flux, shortened energy balance, skewness ,

Abstract # 1073: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
ARE REST BREAKING AGENTS NECESSARY ON APPLES IN SOUTH AFRICA?

North, MS¹, Cook, N² and de Kock, K¹

¹ARC Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch, 7599; ²Deciduous Fruit Producers Trust Research, P.O. Box 12789, Stellenbosch
Email: northm@arc.agric.za

Keywords: apple, delayed foliation, rest breaking ,

Abstract # 1165: A Paper on Crop production / Gewasverbouing
TOMATO SEEDLING HEALTH AND DEVELOPMENT AS INFUENCED BY TRICHODERMA AND MYCORRHIZA APPLICATION

Nzanza, B¹ and Marais, D²

¹ZZ2 Natuurboedery, PO Box 19, Mooketsi 0825; ²Department of Plant Production & Soil Science, University of Pretoria 0002
Email: bombiti@zz2.biz

Keywords: tomato, trichoderma, mycorrhiza ,

Abstract # 1138: A Poster on Soil fertility / Grondvrugbaarheid
NITROGEN MINERALIZATION OF SUNHEMP GREEN MANURE AND MAIZE STOVER RESIDUE MIXTURES IN SOIL

Odhiambo, JJO¹ and Ogola, JBO²

¹University of Venda, Department of Soil Science, P/Bag X5050, Thohoyandou 0950; ²University of Venda, Department of Plant Production, P/Bag Bag X5050, Thohoyandou 0950
Email: Jude.Odhiambo@univen.ac.za

Keywords: Incubation, field capacity, release pattern, synchronize

Abstract # 1110: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
AVENUES FOR IMPROVING PROFITABILITY IN THE ‘BEAUMONT’ MACADAMIA CULTIVAR

Penter, MG¹, Kruger, FJ¹, Nkwana, EM¹ and Nxundu, KY¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: mark@arc.agric.za

Keywords: macadamia, discolouration, post-harvest, quality, profitability, breakage

Abstract # 1113: A Paper on Hort crop protection / Tuinbou gewasbeskerming
SUPPRESSION OF MELOIDOGYNE INCOGNITA RACE 2 ON WATERMELON USING CUCUMIS AFRICANUS AND CUCUMIS MYRIOCARPUS SEEDLING ROOTSTOCKS

Pofu, KM¹ and Mashela, PW¹

¹School of Agricultural and Environmental Sciences, University of Limpopo, P/Bag X1106, Sovenga, 0727, South Africa
Email: mashelap@ul.ac.za

Worldwide, various technologies such as ground leaching and nematode-resistant cultivars are being developed to reduce reliance on halogenated nematicide technologies that have been associated with global warming (Mashela, 2002). The development and use of nematode-resistant seedling rootstocks for watermelon (Citrullus lanatus) production is one such promising technology in the management of the southern root-knot nematode (Meloidogyne incognita). The objective of this study was to determine the host-status and host-sensitivity of two Cucumis species to M. incognita race 2.

Greenhouse studies were separately conducted to test the host-status and host-sensitivity of Cucumis africanus and C. myriocarpus to M. incognita race 2. Treatments, viz. 0, 500, 1000, 1500 and 2000 juveniles and eggs, were arranged in a randomized complete block design with 10 replicates per treatment. Pots containing three-week old seedlings of C. africanus and C. myriocarpus were each infested by dispensing eggs and juveniles using a 20 ml plastic syringe. At harvest, 56 days after inoculation, plant length, shoot weight, stem diameter and nematode numbers were collected as data and analysed using ANOVA through SAS software.

At all four inoculation levels, the reproductive factors (final nematode population/initial nematode population) of M. incognita race 2 on C. africanus and C myriocarpus were less than one, which suggested that the nematode failed to reproduce on the two species. Nematode infection had no effect on the measured growth parameters of C. africanus and C. myriocarpus. Given the lack of nematode reproduction or reduction in plant growth, both Cucumis species tested can be viewed as being resistant to this nematode species.

The two M. incognita-resistant seedling plant species have the potential for use as resistant rootstocks for watermelon production in soil infested with the root-knot nematode. However, further studies are necessary to ensure that the active ingredient preventing nematode infestation in these rootstocks, namely cucurbitacin, is not transferable to watermelon fruits under field conditions.

MASHELA, P.W., 2002. Ground wild cucumber fruits suppress densities of Meloidogyne incognita in tomato crop. Nematropica 32,13 - 19.

Grateful thanks are extended to the National Research Foundation for providing funds.

Keywords: Cucumis africanus, Cucumis myriocarpus , Meloidogyne incognita, resistant rootstocks, reproductive factor,

Abstract # 1089: A Poster on Crop protection / Gewasbeskerming
THE INCIDENCE OF NON-TARGET LEPIDOPTERA SPECIES ON BT AND NON-BT MAIZE IN THE GROBLERSDAL AREA OF SOUTH AFRICA.

Pretorius, J.D¹ and Van den Berg, J¹

¹School of Environmental Sciences and Development, North-West University Potchefstroom 2520, South Africa.
Email: 20425015@nwu.ac.za

The use of Bt maize could directly or indirectly affect non-target organisms. Assessment of the impacts of Bt crops is hampered by the lack of even the most basic checklist of the species present in most systems. In South Africa the maize agroecosystem is of particular interest because of the large area planted with Bt maize for the control of the stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). The aims of this study were to determine the diversity of Lepidoptera species that feed on maize and to assess the possible effects of Bt maize on the incidence of Lepidoptera damage.

Field surveys were conducted on six sites during the 2008/2009 cropping season in the Groblersdal area (Limpopo). Three randomly selected plots consisting of 300 plants each were demarcated inside the Bt maize part of the field as well as the non-Bt refuge.  Each plant was inspected for stem borer damage, boll worm damage, and the incidence of maize steak virus at three two-week intervals starting at the milk stage. Larvae of Lepidoptera were collected from maize and brought to the laboratory where they were reared until adults emerged. The moths were then killed and pinned for identification.

Eight species of Lepidoptera was found of which two were new host records on maize (Caradrina tenebrata [Noctuidae] and Ascotis reciprocaria [Geometridae]). The incidences of Lepidoptera-infested plants and infestation levels were generally lower in Bt fields than in non-Bt fields. On the basis of the high incidence and exposure of the noctuids Helicoverpa armigera and Acantholeucania loreyi they can be considered important non-target herbivores that are exposed to Cry 1Ab protein. Helicoverpa armigera numbers were suppressed on Bt maize. No target pest larvae were recorded on Bt maize, indicating that they have not developed resistance at the surveyed sites.

Two new host plant records of Lepidoptera on maize were recorded. Bt maize significantly suppressed boll worm numbers.

This work forms part of the Environmental Biosafety Cooperation Project between the Republic of South Africa and the Kingdom of Norway coordinated by the Department of Environmental Affairs, Directorate of Nature Management and the South African National Biodiversity Institute. We accordingly give due acknowledgment.

Keywords: Helicoverpa armigera , Caradrina tenebrata , Ascotis reciprocaria, checklist , surveyed,

Abstract # 1156: A Paper on Crop production / Gewasverbouing
ALLELOPATHIC EFFECTS OF AMARANTHUS

Prinsloo, G¹ and Du Plooy, CP¹

¹Private Bag X293 Pretoria 0001
Email: GPinsloo@arc.agric.za

Allelopathy has been described as the inhibition of one plant by another via the release of metabolic by-products into the environment.  It is regarded as a survival mechanism used by plants for interference with the growth of other plants. With increasing interest and consumption of African leafy vegetables as a result of poverty and other factors, these crops are promoted more and more. In a crop rotation production system, Amaranthus may pose serious problems for the follow-up crops if allelopathic effects do exist. The project investigated the allelopathic effects of different Amaranthus species on different vegetable crops and weed species. 

A field experiment, pot trial and seed germination trial were conducted at the ARC-Roodeplaat VOPI. The field trial was conducted by planting Amaranthus at two different spacings. The recommended spacing of 20cm in row and 25 cm between rows as well as a wider spacing of 20cm in row and 50 cm between rows were used. The trial was conducted as a Randomised Complete Block Design (RCBD) with four replicates with plot sizes of 3m x 3m. The Amaranthus plants were allowed to reach maturity and were ploughed back into the soil before spinach, tomato, cabbage and green pepper seedlings were planted on the same area. Tomatoes and green peppers were planted in five rows with four plants per row, yielding 6 data plants. Cabbage and spinach were planted in five rows with seven plants per row yielding fifteen data plants. In the pot trial the allelopathic effect of different Amaranthus species and different plant parts of Amaranthus was assessed.  A RCBD design with three replicates and five treatments was used. Amaranthus seedlings were allowed to reach maturity in the pots after which different plant parts of Amaranthus were incorporated into the soil to determine the effects of the different plant parts on tomato seedlings. The seed germination trial investigated the effects of a crude Amaranthus extract at 50mg/ml and 25 mg/ml on the germination of seeds of two vegetable crops and three weed species.  A RCBD design with three replicates and fifteen treatments per replicate was used. 

Initial results revealed that the Amaranthus extracts inhibited seed germination of vegetable and weed seeds. No differences were observed between the extracts of different plant parts of Amaranthus.  The results for the field and pot trials are in the process of being analysed.

Allelopathic effects on both vegetable and weed seeds have been observed in the seed germination trial. If the results from the field and pot trials would support those findings, management of Amaranthus production needs to consider the potential effects which allelochemicals may have on vegetable production on the same soils.

Funding from the Gauteng Department of Agriculture and Rural development.

Keywords: Allelopathy, Amaranthus, vegetables ,

Abstract # 1083: A Paper on Crop breeding & adaptation / Gewasveredeling & aanpassing
A VARIETY SELECTION DECISION SUPPORT SYSTEM FOR SUGARCANE BASED ON GENOTYPE-BY-ENVIRONMENT ANALYSES

Ramburan, S¹, Paraskevopoulos, A¹, Jones, M¹ and Saville, G¹

¹Private Bag X02 Mount Edgecombe 4300
Email: Sanesh.Ramburan@sugar.org.za

Improvements in plant breeding procedures, combined with strategies to release niche specific varieties have contributed to increased variety numbers in the South African sugarcane industry, often complicating variety selection for growers. The objective of this study was to develop a decision support system (DSS) based on industry legalities, varietal characteristics, and structured genotype-by-environment (G x E) analyses, to assist users with variety selection decisions.

Long-term data extracted from the variety trial database of the South African Sugarcane Research Institute (SASRI) were categorized according to different agro-climatic regions, harvest ages (12, 18, 24-month) and harvest seasons (early, mid, late season harvests). Restricted maximum likelihood (REML) analyses were conducted regionally to determine varietal adaptability to different harvest ages and seasons. Varietal adaptability to different yield potential conditions was determined by regressing  varietyl mean yields against trial mean yields, and varietal adaptability was interpreted from the slope of the regression curves.  All analyses were translated into “yes/no” decision matrix  in a relational database, which was linked to a web interface. The system allows users to specify regional, harvest age, season, water regime, pest and disease, and yield potential characteristics of their production environment, selects appropriate varieties that conform to specified criteria, and eliminates non-compliers in a stepwise approach. The system was validated against expert opinion (Extension specialists.

Highly significant (p<0.001) variety x age and variety x season interactions were observed in all regions, which allowed appropriate characterisation of varieties. Regression analyses demonstrated varied stability of varieties across regions depending on the environmental yield potential. A total of 76 different production scenarios were tested, and on average the DSS selected a greater number (p<0.01) of varieties compared to experts, with 73% of the DSS selections corresponding exactly to expert opinion. When averaged across regions, the success (% of DSS selections accepted by experts) of the system was estimated to be 84%. The factors investigated in this study were considered as priorities in a logical hierarchy influencing sugarcane production in the industry. However, further refinement of the system will include analysis of environmental covariates and their inclusion into the DSS.

The study has shown that statistical analyses of priority factors affecting productivity can be employed to broadly characterise varieties, and such characterisations can be adapted successfully into a selection tool that conforms to advice from field experts. Further inclusion of actual trial yield data into the system will allow users to view and compare variety performance at a local level to further assist with variety selection.

Keywords: Sugarcane, Variety, Genotype-by-environment, Decision support system

Abstract # 1094: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
EFFECT OF SYSTEMIC FUNGICIDES AND GROWTH REGULATORS ON THE OIL YIELD AND COMPOSITION OF ROSE GERANIUM (PELARGONIUM CV ROSE)

Ras, AM¹

¹Department of Agriculture, Dohne ADI, P/Bag X15, Stutterheim, 4930
Email: bertie.ras@agr.ecprov.gov.za

Keywords: rose geranium, systemic fungicides, growth retardants, oil yield, oil composition,

Abstract # 1092: A Paper on Hort nutrition & water management / Tuinbou voeding & waterbestuur
EFFECTS OF SILICON ON QUALITY AND MALONDIALDEHYDE CONTENT OF CUT ROSE (ROSA X HYBRIDA L.) CV. HOT LADY UNDER SALT STRESS

Reezi, S¹, Babalar, M¹, Kalantari, S¹, Okhovvat, SM² and Byoung , RJ³

¹Department of Horticulture, Faculty of Agriculture, University of Tehran, Karaj, Iran; ²Department of Plant Pathology, Faculty of Agriculture, University of Tehran, Karaj, Iran; ³Department of Horticulture, Division of Applied Life Science (BK21 Program), Graduate School, Gyeongsang National University, Jinju, Korea 660-701
Email: sreezi57@yahoo.com

Keywords: Silicon, hydroponics, mineral nutrition, floriculture

Abstract # 1134: A Poster on Soil biology / Grondbiologie
PRELIMINARY INVESTIGATION OF YEAST DIVERSITY IN MAIZE PRODUCING SOILS

Rhode, OHJ¹, Bezuidenhout, CC² and Van Wyk, DAB²

¹ARC-Grain Crops Institute, P/Bag X1251, Potchefstroom 2520; ²School of Environmental Sciences and Development, North-West University, P/Bag X600, Potchefstroom 2520
Email: RhodeO@arc.agric.za

Keywords: soil yeast diversity, maize production

Abstract # 1105: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
INTERACTION BETWEEN AVOCADO FRUIT MATURITY, 1-METHYLCYCLOPROPENE APPLICATION RATE, STORAGE TEMPERATURE AND STORAGE PERIOD ON THE QUALITY OF 'FUERTE' AND 'HASS' AVOCADO FRUIT

Roets, NJR¹, Lemmer, D¹ and Kruger, FJ¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: nico@arc.agric.za

South Africa was the first avocado-producing country to successfully commercialize 1-methylcyclopropene (1-MCP; SmartFresh^SM). During the last decade, the initial set of laboratory trials was followed by static container trials and commercialization. The patent holder (Rohm & Haas, USA) annually commissions a set of relevant trials aimed at continuously upgrading the technology. Results of a study conducted during 2009 aimed at characterizing the interaction between 1-MCP application rates and storage temperature settings will be presented.

‘Fuerte’ and ‘Hass’ fruit, count 18, were obtained from a local pack house during the onset, the middle and the end of the packing season. During these three periods maturity levels for ‘Fuerte’ were 75, 68 and 66% moisture content respectively and for ‘Hass’ 72, 69 and 67% respectively. Fruit were treated with 0, 200, 300 and 500 ppb SmartFresh^SM and stored for a 40 day period with early season fruit at 6° and 8°C, mid-season fruit at 5° and 7°C and late season fruit at 4° and 6°C. In each case one box of count 18 fruit was ripened on day 20, 25, 30, 35 and 40 at 19°C. Ripening period, physiological disorders and fungal infections were recorded.

For both ‘Fuerte’ and ‘Hass’, at all storage temperatures and maturities, ripening followed similar patterns. SmartFresh^SM displayed an increase in mean days to ripen (DTR) as the concentration increased on days 20, 25 and 30. The effect of SmartFresh^SM became weaker on days 35 and 40. A slight decrease in mean DTR also occurred as the storage period was increased. For ‘Fuerte’ the incidence of grey pulp increased as the season progressed, while only a slight increase was observed for the control ‘Hass’ fruit stored at lower temperature regimes for 35 and 40 days. SmartFresh^SM and storage temperature did not affect incidence of fungal diseases, but there were trends between the different maturity levels (time of season).

Ripening of ‘Hass’ and ‘Fuerte’ avocado fruit was influenced by SmartFresh^SM concentration and storage period, but not by maturity or the time of the season. Physiological disorders and diseases were, on the other hand, not significantly influenced by SmartFresh^SM concentrations or storage temperatures, but by the time of the season.

Keywords: avocado, SmartFreshSM, storage temperatures, storage period, maturity level, ripening

Abstract # 1196: A Paper on Crop production / Gewasverbouing
TUFA, A NEW GROUNDNUT CULTIVAR IN SOUTH AFRICA

Salomon, L¹

¹ARC-GCI, Private Bag X1251, Potchefstroom 2520
Email: SalomonL@arc.agric.za

Keywords: Tufa, Groundnut

Abstract # 1117: A Paper on Agrometeorology / Agrometeorologie
SENSIBLE HEAT FLUX AND EVAPORATION USING ITERATION

Savage, MJ¹

¹University of KwaZulu-Natal, P/Bag 01, Scottsville 3201
Email: savage@ukzn.ac.za

Keywords: Energy balance, iterative procedure, MOST, Penman-Monteith, surface renewal, temperature variance

Abstract # 1152: A Paper on Crop nutrition & water / Gewasvoeding & water
EFFECTS OF PHOSPHATE LEVELS ON ROSE GERANIUMS (PERLAGONIUM GRAVEOLENS) PRODUCTION

Sedibe, MM¹ and Allemann, J²

¹School of Environmental Health and Agriculture, Central University of Technology, Free State, P/Bag X20539, Bloemfontein 9301; ²Department of Soil, Crop and Climate Sciences, Faculty of Natural and Agricultural Sciences, PO Box 339, Bloemfontein 9300
Email: msedibe@cut.ac.za

Keywords: Oil quality, P-levels

Abstract # 1143: A Paper on Hort biotechnology, breeding &development / Tuinbou biotegnologie, veredeling & ontwikkeling
DEVELOPMENT OF A STANDARD SET OF MICROSATELLITE MARKERS FOR THE IDENTIFICATION OF GUAVA CULTIVARS AND SELECTIONS

Severn-Ellis , AA¹, Schoeman, M¹ and Willemse, S¹

¹ARC Institute for Tropical and Subtropical Crops, P/Bag X11208, Nelspruit, 1200
Email: anitas@arc.agric.za

Guava varieties are multiplied through vegetative propagation, which requires routine verification of the clonal material. To avoid misidentification and to protect the Plant Breeders’ Rights, an efficient identification tool is required. Microsatellites, or simple sequence repeats (SSRs), are a resourceful tool available for fingerprinting due to their ubiquitous distribution along the eukaryotic genome, high level of polymorphism, co-dominant inheritance and robustness (Powell et al., 1996). A number of SSR markers for Psidium guajava L. were developed by Risterucci et.al (2005) for cultivar identification, linkage mapping and potential inter-specific genetic studies. A sub-set of these markers was tested in this study.

Leaves were collected from selected plants in the nursery and orchard. The DNA was extracted according to a modified CTAB DNA extraction procedure (Risterucci et al., 2005). PCR amplification using SSR primer pairs was carried out, whereafter amplification products were resolved and scored on a 2% agarose gel. The parameters used to evaluate the information rendered included the number of alleles per locus and observed heterozygosity.

A total of 45 guava selections and cultivars were analyzed with ten SSR primer pairs that rendered reproducible polymorphisms. These informative SSR primer pairs were selected from a larger set of SSRs after evaluation of a smaller sub-sample of guava cultivars. Most guava selections could be identified using a set of 3-4 SSR primer pairs.

SSR markers could be successfully used in the identification of guava selections and cultivars. Polymorphisms revealed in this preliminary study will further be used in genetic mapping, marker-assisted selection and germplasm characterization.

POWELL, W., MACHRAY, G.C. & PROVAN, J., 1996. Polymorphism revealed by simple sequence repeats. Trends Plant Sci. 1, 215-222.

RISTERUCCI, A.M., DUVAL, M.F., ROHDE, W. & BILLOTTE, N., 2005. Isolation and characterization of microsatellite loci from Psidium guajava L. Mol. Ecol. Notes 5, 745–748.

The author would like to thank the ARC for funding provided.

Keywords: Microsatellite , markers , guava ,

Abstract # 1172: A Paper on Industry research presentations / Industrie - navorsing
MONITORING OF RANGELAND QUALITY BY MEANS OF LOW ALTITUDE REMOTE SENSING

Shaker, P¹, Dannhauser, CS¹ and Fouché, PS¹

¹Department of Soil Science, Plant Production and Remote Sensing, University of Limpopo, Turfloop Campus, P/Bag X1106, Sovenga 0727
Email: mpshaker@gmail.com

Keywords: Infrared imagery, rangeland, remote sensing ,

Abstract # 1111: A Paper on Soil fertility / Grondvrugbaarheid
SOIL CHEMICAL CHARACTERIZATION IN CONTRASTING CROPPING SYSTEMS UNDER LAND REFORM PROGRAMME INDIA

Shoko, MD¹, Moyo, S¹ and Mkwamba, S¹

¹Faculty of Agriculture and Natural Resources, Africa University, Box 1320, Mutare, Zimbabwe
Email: shokom@africau.ac.zw

Keywords: A1, A2, communal, production systems, soil nutrients,

Abstract # 1074: A Paper on Hort post-harvest biology & technology / Tuinbou na-oes biologie & tegnologie
THE EFFECT OF METHYL JASMONATE AND SALICYLIC ACID ON CHILLING INJURY OF ’EUREKA‘ LEMONS

Siboza, XI¹, Bower , JP¹ and Bertling , I¹

¹Horticultural Science, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa
Email: 208529751@ukzn.ac.za

Keywords: chilling injury, methyl jasmonate, salicylic acid, anti-oxidants

Abstract # 1072: A Paper on Crop modelling / Gewasmodelering
MODELLING CROP GROWTH AND CROP WATER RELATIONS IN SOUTH AFRICA: PAST ACHIEVEMENTS AND LESSONS FOR THE FUTURE

Singels, Abraham¹, Annandale, JG², De Jager, JM³, Schulze, RE⁴, Inman-Bamber, NG⁵, Durand, W⁶, van Rensburg, LD³, van Heerden, PS⁷, Crosby, CT⁷, Green, GC⁸ and Steyn, JM²

¹Private Bag X02 Mount Edgecombe 4300; ²University of Pretoria; ³University of the Free State; ⁴University of Kwazulu-Natal; ⁵CSIRO, Townsville Australia; ⁶ARC-Grain Crops Institute Potchefstroom; ⁷PICWAT Bloemfontein; ⁸PO Box 523 Betty's baai
Email: abraham.singels@sugar.org.za

Mathematical simulation of crop growth and water relations has become indispensable to agricultural science and practice. A critical assessment of how modelling contributed to the development of crop science and to the management of crop production and natural resources in South Africa (SA) over the past 25 years could give new perspectives on the benefits derived from modelling, the appropriateness of approaches employed and the best way forward.

The initial objectives of the major SA modelling initiatives (ACRU, BEWAB, CANEGRO, CERES, PUTU, SAPWAT, SWB) dictated the approaches that were followed and determined the impacts thereof. Significant advances were made with regard to improved understanding of crop growth and water use and adapting models for local conditions such as for example dryland grain crop production under very low rainfall. Modelling provided invaluable support for strategic investigations into the impacts of climate change, land use and water use. Many of the models succeeded in providing much needed information to improve tactical and operational management of irrigated and dryland agriculture. Some models have been (and are being) used operationally to forecast crops (maize, wheat and sugar) and to monitor droughts in natural vegetation, adding value to the respective industries.  

Modelling has formed, in some cases, an integral part of tertiary education in crop science and hydrology. This should be strengthened to build more capacity to address the ever-increasing complexity of challenges in agriculture. 

The review identified factors that are crucial for modelling to maintain effective impacts on the science and practice of crop production and natural resource use. These were excellent scientific leadership, long term funding, effective collaboration between local and with international groups, expertise on local agronomy and good quality experimental data for model testing and adaptation. Future modelling efforts should explore opportunities to integrate information obtained from technologies such as remote sensing and genomics.

Keywords: crop model, irrigation, water balance, management, hydrology, simulation

Abstract # 1179: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
TECHNOLOGY APPLICATION CASE STUDY: USING 3DMAPPERTM FOR SOIL SURVEY ANALYSIS NEAR BREYTON IN MPUMALANGA

Smith, HJC¹, Hensley, M², Le Roux, PAL² and Van Tol, JJ²

¹Digby Wells & Associates, Randburg, South Africa; ²University of the Free State, Department of Soil, Crop and Climate Sciences, Bloemfontein 9301
Email: hendrik@digbywells.co.za

Keywords: predictive, soil , mapping ,

Abstract # 1201: A Paper on Crop physiology / Gewasfisiologie
EMMER AS A SOURCE OF IMPROVED WATER USE EFFICIENCY FOR WHEAT

Sparkes, DL¹, Diaz-Alves, A and Isaack, M

¹University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK, LE12 5RD
Email: debbie.sparkes@nottingham.ac.uk

Keywords: Emmer, water use efficiency, wheat ,

Abstract # 1131: A Paper on Crop nutrition & water / Gewasvoeding & water
NITROGEN BASED SLUDGE LAND APPLICATION IN AGRONOMIC CROPS: AGRONOMIC AND ENVIRONMENTAL IMPLICATIONS

Tesfamariam, EH¹, Annandale, JG¹, Steyn, JM¹ and Stirzaker, RJ²

¹Department of Plant Production and Soil Science, University of Pretoria, Pretoria, South Africa.; ²CSIRO Land and Water, P.O.Box 1666, Canberra, Australia, 2061, and CRC for Irrigation Futures
Email: tesfamariam@tuks.co.za

Beneficial agricultural use of treated municipal sludge is a well known practice around the world. Nevertheless, only 28% of the sludge produced in South Africa is beneficially utilized on agricultural lands. A lack of local knowledge about the benefits and disadvantages of sludge has contributed to the low utilisation. The South African Sludge Guidelines used to allow an annual upper application limit of 8 t ha^-1, but was recently increased to 10 t ha^-1. This report recommends local field scale studies to verify the guideline. The overall objective of this study was to investigate the dynamic nature of sludge loading for optimal crop production and to assess the potential environmental impacts through nitrate leaching and P accumulation in the soil profile.

Field experiments were conducted on a clay loam soil planted to dryland maize (Zea mays L.) and irrigated maize-oat (Avena sativa L.) rotation at the East Rand Water Care Works (ERWAT), Johannesburg, Gauteng, South Africa. Plots of 25 m² were arranged in a randomized complete block design comprising four replications of five treatments. An 8 t ha^-1 sludge control treatment was compared with 0, 4, and 16 t ha^-1 yr^-1 rates and an inorganic fertilizer (NPK 2:3:2, KCl, and LAN). The sludge used in this study was anaerobically digested and paddy-dried having acceptable quality for agricultural use. During the study, both sludge and inorganic fertilizer were broadcast and immediately incorporated into the soil.

Doubling the old annual 8 t ha^-1 sludge norm significantly (P≤0.05) increased grain and forage yield of both dryland maize and the irrigated maize-oat rotation. Export of N in forage was approximately double that exported in the grain above. Nitrogen exported in forage from the irrigated rotation was at least three times higher than that from similar sludge loading rates under dryland maize production. Mass balance calculations involving N applied, N exported in product and change in soil N storage revealed substantial losses from the system, particularly under irrigated conditions. Soil solution samples collected from 0.3 and 0.6 m deep wetting front detectors under the irrigated maize-oat rotation indicated a low risk of groundwater pollution through nitrate leaching. The risk of leaching was higher with the use of inorganic fertilisers. Sludge applied according to crop N demand would result in total and Bray-1P accumulation in the soil profile and could pose a threat to surface water pollution with time.

Ideally the upper sludge limit to satisfy crop N demand should be dynamic because it depends on the sludge N content, the intensity of cropping, and the availability of water. Ultimately, maximum sludge loading will depend on the accumulation of P and the risk this poses for pollution.

Funding from WRC, ERWAT, and SASOL is gratefully acknowledged

Keywords: Sludge, Nitrogen, Phosphorus, Leaching, Maize, Oats

Abstract # 1128: A Paper on Hort physiology / Tuinboufisiologie
CATECHIN AND EPICATECHIN PHENOLICS IN ‘HASS’ AVOCADO TISSUES

Tesfay, SZ¹, Bertling, I¹ and Bower, JP¹

¹Horticultural Science, School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, P/Bag X01, 3209, Scottsville, Pietermaritzburg, South Africa
Email: szeray@gmail.com

Various researchers have reported that fruit exocarp and seed have greater amounts of free phenols than of bound ones. The moieties conjugate via the hydroxyl groups of the phenolics, thereby reducing their ability to function as strong antioxidants. As silicon has been found to interact in the phenolic pathway, potassium silicate treatments could be used to either release free phenols from the conjugates or increase the phenol concentration in fruit tissue, resulting in increased antioxidant activity of such tissue. The objective of this research was to study the pre-harvest production and distribution of the major avocado phenolics, catechin and epicatechin (free and bound forms), in fruit tissues. Understanding the production and distribution of these two phenols, and the effect of a postharvest application of silicon on the concentration of these phenols and/or their forms, will aid in improving fruit quality.

MATERIALS AND METHODS

Mature postharvest fruit (32% oil g/g dry weight) were treated by dipping them into solutions with different concentrations of potassium silicate (0, 5, 13, 25 x 10³ppm) for 40 min, storing them at 5.5°C for 28 days and thereafter allowing them to soften at room temperature. Total phenolics were determined spectrophotometrically while the concentration of individual phenols was determined by HPLC. Lipid peroxidation was determined spectrophotometrically, while electrolyte leakage and catalase activity were analyzed according to Tesfay et al. (in press). Catalase expression was visualized using a Western blot and statistical evaluation of data was performed using GenStat 11^th edition.

RESULTS AND DISCUSSION

Phenolics are not evenly distributed in fruit. The accumulation of soluble phenolic compounds is generally greater in external tissues of fleshy fruit than in internal tissues. It was, hence, not surprising to find a significantly lower phenolic concentration in mesocarp than in exocarp tissue. Fruit quality was improved by Si treatment, probably due to reduced electrolyte leakage and lipid peroxidation, and as a result of increased catalase expression and a 10-20% increase in catalase activity.

CONCLUSION

Results confirm the potential of potassium silicate to significantly improve postharvest fruit quality through an increased antioxidant pool in fruit, and particularly by increasing free phenols and catalase expression in mesocarp tissue.

TESFAY, S.Z., BERTLING, I. & BOWER, J.P., (in press). Levels of anti-oxidants in various tissues during maturation of ‘Hass’ avocado (Persea americana Mill.). J. Hortic. Sci. Biotech.

Keywords: epicatechin, catechin

Abstract # 1150: A Paper on Agrometeorology / Agrometeorologie
RAINFALL-RUNOFF RELATIONSHIPS AS INFLUENCED BY RUNOFF TO BASIN AREA RATIOS AND MULCHING RATES IN BAINSVLEI KENILWORTH ECOTOPE

Tesfuhuney , WA¹, Walker, S¹ and Van Rensburg, LD¹

¹Department of Soil, Crop and Climate Sciences, University of Free State, PO Box 339, Bloemfontein 9300
Email: weldit78@yahoo.com

Keywords: Rainfall-runoff relationship, runoff strip length, mulching rate ,

Abstract # 1071: A Paper on Crop production / Gewasverbouing
THE INFLUENCE OF PLANTING DENSITY ON GRAIN YIELD AND QUALITY OF SPRING WHEAT CULTIVARS UNDER IRRIGATION

Tolmay, JPC¹

¹ARC-Small Grain Institute Private Bag X29 Bethlehem 9700
Email: tolmayj@arc.agric.za

Keywords: spring wheat, no-till planting, row width, planting density

Abstract # 1088: A Paper on Crop protection / Gewasbeskerming
DOES BT MAIZE HAVE AN EFFECT ON ARTHROPOD BIODIVERSITY IN MAIZE FIELDS?

Truter, J¹, Van den Berg, J¹ and Van Hamburg, H¹

¹School of Environmental Sciences and Development, North-West University, P/Bag X6001, Potchefstroom 2520
Email: 20070570@nwu.ac.za

Keywords: Biodiversity, GM maize

Abstract # 1133: A Paper on Crop breeding & adaptation / Gewasveredeling & aanpassing
GENETIC ANALYSIS OF DOUGH MIXING STRENGTH AND BREAD-MAKING PROPERTIES OF THE HARD RED SPRING WHEAT BREEDING LINES MN98550 AND MN99394

Tsilo, TJ¹, Chao, S², Hareland, GA³ and Anderson, JA¹

¹University of Minnesota, St. Paul, MN 55108, USA; ²Biosciences Research Laboratory; ³Wheat Quality Laboratory, USDA-ARS, Fargo, ND 58105, USA
Email: tsilo001@umn.edu

The development of wheat varieties with high yield and acceptable grain quality traits is a major focus for many breeding programs worldwide. However, full-scale end-use quality evaluation is not routinely performed on breeding material, because the process is time-consuming, laborious, and costly, but could be facilitated through the use of genetic and molecular biological selection procedures. In this study, we identified chromosome regions influencing dough-mixing strength and bread-making properties of hard red wheat breeding lines adapted to the Upper Midwest region of the U.S.

Plant Materials: A mapping population of 139 recombinant inbred lines (RILs, F_6:8) was developed from the MN98550 x MN99394 cross. Parents, RILs, and three check varieties were grown in yield plots in a randomized complete block design.

Quality Analyses: Dough mixing strength was evaluated using a computer-based 35-g mixograph according to AACC Method 54-40A (AACC 2000). Properties included mixograph pattern (MIXOPA),midline peak time (MPT), midline peak integral (MPI), midline peak value (MPV), and midline peak width (MPW). Bread-making properties were evaluated using 25-g flour samples (AACC Method 10-10B). Bake mixing time (BMT), loaf volume (LV), bake water absorption (BWA), and bread crumb properties were evaluated. ANOVA was performed using GLM PROC of SAS 9.1 (SAS Institute, Cary, NC). Broad-sense heritability estimates were obtained for all traits.

Marker Assay and QTL Analysis: A genetic linkage map was constructed with 531 SSR and DArT marker loci that spanned a distance of 2,505 cM over the whole genome of wheat. QTL analyses were performed using composite–interval mapping in WinQTL Cartographer v. 2.5 (Wang et al. 2005). A QTL was declared when the LOD score was greater than a threshold level of 2.5.

Because the RILs were highly homogeneous (F_6:8), heritability estimates were high (0.79 - 0.94) for all dough mixing strength and bread-making properties with the exception of crumb properties. Strong correlations were observed among MPT, MPI, and BMT (r > 0.93 at P < 0.001) and among MPV, MPW and BWA (r > 0.72 at P < 0.001), indicating that those properties share some genes in common.

QTL analysis identified forty-three QTL over 13 wheat chromosomes controlling 10 dough mixing strength and bread-making properties. The high-molecular weight glutenin genes Glu-B1 and Glu-D1 were major QTL clusters on chromosomes 1B and 1D that influenced all five mixograph traits, BMT and LV, whereas BWA was mainly influenced by 1B. A third QTL cluster on 6D influenced four mixograph and bake mixing time related properties (MIXOPA, MPT, MPI, BMT). Additional minor QTL clusters on chromosomes 1B and 7D influenced mixing time related properties (MPT and MPI). A QTL cluster on 1A influenced MPV and MPW.

AACC. 2000. Approved Methods of the American Association of Cereal Chemists, 10^th Ed. The Association: St. Paul, MN.

Wang, S., Basten, C.J., Zeng, Z.B. 2005. Windows QTL Cartographer 2.5. North Carolina State University, Raleigh

Keywords: Wheat, Dough mixing strength, Bread-making , Quantitative trait locus

Abstract # 1205: A Paper on Keynote speech
OPPORTUNITIES FOR HORTICULTURE AND HORTICULTURAL SCIENCE IN A GLOBAL CONTEXT

Van Assche, J¹

¹ISHS Executive Director, P.O. Box 500, 3001 Leuven 1 Belgium
Email: Jozef@ishs.org

Keywords: C2C ,

Abstract # 1058: A Paper on Soil physics / Grondfisika
ESTIMATING LEACHING LOSSES FROM MOBILE AND IMMOBILE SOIL WATER NITRATE CONCENTRATIONS

Van der Laan, M¹, Stirzaker, RJ², Annandale, JG¹, Bristow, KL² and Du Preez, CC³

¹University of Pretoria, Pretoria 0002; ²CSIRO Land & Water and CRC for Irrigation Futures, Australia; ³University of the Free State, Bloemfontein 9300
Email: mvdlaan@tuks.co.za

Keywords: Nitrogen, nitrate, leaching, monitoring, modelling, SWB-Sci

Abstract # 1184: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
THE NATURE OF AEOLIAN DEPOSITS IN THE SOUTH WESTERN FREESTATE

Van der Merwe, RH¹ and Le Roux, PAL¹

¹Dept. Soil, Crop and Climate Sciences, University of the Free State, PO Box 339, Bloemfontein 9300
Email: vandermerwerh.sci@uovs.ac.za

Keywords: sand dunes, clay bodies, hydraulic soil properties, irrigation scheme

Abstract # 1195: A Paper on Crop nutrition & water / Gewasvoeding & water
LABORATORY AND RAPID FIELD PROCEDURE TO CALIBRATE EC-10 AND EC-20 CAPACITANCE SENSORS IN COIR

Van der Westhuizen, RJ¹ and Van Rensburg, LD²

¹PO Box 29229, Danhof 9310; ²Department of Soil, Crop and Climate Sciences, Faculty of Natural and Agricultural Sciences, University of the Free State, PO Box 339, Bloemfontein 9300 9300
Email: caryki@iburst.co.za

The use of capacitance water sensors for the scheduling of irrigation for hydroponic tomato and cucumber crops grown in coir was investigated. Laboratory experiments in a climate controlled chamber were conducted to accurately calibrate ECH₂O capacitance sensors, models EC-10 and EC-20, in coir with an improved calibration procedure. Water content predictions by the coir-specific calibration and manufacturer’s calibration equations were compared to actual water content measured from mass loss of the coir sample. The manufacturer’s calibration equation indicated a poor accuracy of prediction, which mostly underestimated the volumetric water content, compared to the near perfect prediction of the coir‑specific calibration of individual sensors. A rapid calibration procedure for EC-10 and EC-20 sensors was proposed to reduce the calibration time of the sensors and promote their commercial use for irrigation management in coir. The accuracy of prediction by the rapid calibration procedure for the plant available water content range was high for both EC-10 and EC-20 sensors and allowed for the compensation for variation between sensors.

Keywords: Capacitance sensors, coir, water content ,

Abstract # 1200: A Paper on Crop protection / Gewasbeskerming
A CLIMATIC SOYBEAN RUST FORECAST MODEL

Van Niekerk, LM¹, Bezuidenhout, CN¹, Caldwell, PM¹, Van Rij, N² and Kunz, R¹

¹University of KwaZulu-Natal – Pietermaritzburg Campus, P/Bag X01, Scottsville 3209; ²Crop Protection, Department of Agriculture, Cedara, South Africa
Email: 204517649@ukzn.ac.za

Keywords: Algorithm, climatic vulnerability, modelling, soybean rust

Abstract # 1210: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
SOIL MAPPING IN AFRICA AT THE CROSSROADS: WORK TO MAKE UP LOST GROUND

Van Ranst, E¹ and Verdoodt, A¹

¹Laboratory of Soil Science, Ghent University, Belgium
Email: lerouxpa.sci@ufs.ac.za

Keywords: GIS, soil mapping

Abstract # 1185: A Paper on Crop protection / Gewasbeskerming
EXPRESSION OF THE MON810 BT EVENT IN VARIOUS GENETIC BACKGROUNDS OF MAIZE

Van Rensburg, JBJ¹

¹ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom 2520
Email: koosj@arc.agric.za

Keywords: Busseola fusca, Bt maize

Abstract # 1162: A Paper on Soil physics / Grondfisika
ESTIMATING THE SPATIAL DISTRIBUTION OF PROFILE AVAILABLE WATER CAPACITY AND SOIL WETNESS IN A COMMERCIAL CROP LAND USING THE EM38

Van Rensburg , LD¹, Bothma, CB² and Le Roux, PAL¹

¹University of the Free State, PO Box 339, Bloemfontein 9301; ²GWK Bpk. Douglas, Posbus 47, Douglas 8730
Email: Vrensbl.sci@ufs.ac.za

Keywords: Soil variability, EM38, soil wetness, profile available water capacity

Abstract # 1085: A Paper on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
INTEGRATING BIOLOGICAL MANAGEMENT PRACTICES INTO POME FRUIT PRODUCTION SYSTEMS

Van Schoor, L¹, Stassen, PJC¹ and Botha, A²

¹ARC Infruitec-Nietvoorbij, P/Bag X5026, Stellenbosch, 7599; ²Department of Microbiology, University of Stellenbosch, Private Bag X1, Matieland, 7602
Email: vschoorL@arc.agric.za

Keywords: compost, compost extract, pear, Bacillus, humate, seaweed

Abstract # 1171: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
PREDICTING STREAMFLOW FROM THE SOIL MAP IN THE WEATHERLEY CATCHMENT

Van Tol, JJ¹ and Le Roux, PAL¹

¹University of the Free State, PO Box 339, Bloemfontein 9300
Email: vantoljj.sci@ufs.ac.za

Keywords: Hillslope hydrology, hydrograph, interflow soils, recharge soils, responsive soils,

Abstract # 1173: A Paper on Soil genesis, classification & Mapping / Grondgenese, klassifikasie & kartering
SOIL EROSION ON A TOPO-SEQUENCE IN MAPHUTSENG, LESOTHO

Van Zijl, G¹, Ellis, F¹ and Rozanov, A¹

¹Department of Soil Science, Stellenbosch University, P/Bag X1, Matieland, 7602
Email: gvzijl@gmail.com

Keywords: Gully erosion, Lesotho, Water dispersible clay, GIS

Abstract # 1101: A Poster on Hort production & cultivation practices / Tuinbou verbouing & bewerkingspraktyke
SUNBURN REDUCTION ON 'MIHO WASE' SATSUMA MANDARINS USING PARTICLE FILM TECHNOLOGY

Verreynne, JS¹ and van Kerwel, W²

¹Citrus Research International, Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602; ²Department of Horticultural Science, University of Stellenbosch, P/Bag X1, Matieland, 7602
Email: sv@cri.co.za

Keywords: Citrus, kaolin, particle film technology, sunburn

Abstract # 1084: A Poster on Alien invader plants / Uitheemse indringerplante
PRELIMINARY EVALUATION OF RESIDUAL HERBICIDES FOR CONTROL OF SILVER-LEAF BITTER APPLE (SOLANUM ELAEAGNIFOLIUM CAV.)

Viljoen, B D¹, Stoltsz, C W¹ and Van der Rijst, M²

¹Agricultural Research Council, Plant Protection Research Institute, P O Box 318, Uitenhage, 6230; ²Agricultural Research Council, Biometry Unit, P/Bag X5013, Stellenbosch, 7599
Email: ViljoenB@arc.agric.za

Keywords: alien invader plant, chemical control, residual herbicides, noxious weed, satansbos, silverleaf nightshade

Abstract # 1106: A Paper on Alien invader plants / Uitheemse indringerplante
PRIORITISING CATCHMENTS FOR INVASIVE ALIEN PLANT CONTROL

Wannenburgh, AM¹, Forsyth, GG², Le Maitre, DC² and Van Wilgen, BW²

¹Working for Water Programme, P/Bag X4390, Cape Town 8000; ²CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch 7599
Email: wannena@dwaf.gov.za

Keywords: Invasive alien plants, prioritisation, catchment ,

Abstract # 1097: A Paper on Soil fertility / Grondvrugbaarheid
ASSESSING SOIL ORGANIC CARBON (SOC) CHANGES BY MEANS OF THE HOT WATER EXTRACTABLE CARBON (HWEC) FRACTION

Weigel, A¹, Schulz, E², Eustice, T³, Naidoo, G¹ and Van Antwerpen, R¹

¹South African Sugarcane Research Institute, P/Bag X02, Mount Edgecombe 4300, South Africa; ²Helmholtz Centre for Environmental Research – UFZ, Theodor-Lieser-Str.4, 06120 Halle, Germany; ³South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, South Africa
Email: Annett. Weigel@sugar.org.za

Keywords: soil sustainability, soil carbon fractions, labile carbon, hot water extractable carbon, soil health indicator,

Abstract # 1147: A Paper on Soil physics / Grondfisika
INFLUENCE OF RAINFALL INTENSITY PATTERNS ON INFILTRATION AND RUNOFF UNDER IN-FIELD RAINWATER HARVESTING

Zerizghy, MG¹ and Van Rensburg, DL¹

¹University of the Free State, Department of Soil, Crop & Climate Sciences (54), PO Box 339, Bloemfontein 9300
Email: Zerizghymg.sci@ufs.ac.za

Keywords: water harvesting, rainfall intensity, runoff, infiltration, soil water,