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Journal articles on the topic "Tuber crops south africa"
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Egbebiyi, Temitope Samuel, Olivier Crespo, Christopher Lennard, Modathir Zaroug, Grigory Nikulin, Ian Harris, Jeff Price, Nicole Forstenhäusler, and Rachel Warren. "Investigating the potential impact of 1.5, 2 and 3 °C global warming levels on crop suitability and planting season over West Africa." PeerJ 8 (May 5, 2020): e8851. http://dx.doi.org/10.7717/peerj.8851.
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West African rainfed agriculture is highly vulnerable to climate variability and change. Global warming is projected to result in higher regional warming and have a strong impact on agriculture. This study specifically examines the impact of global warming levels (GWLs) of 1.5°, 2° and 3 °C relative to 1971–2000 on crop suitability over West Africa. We used 10 Coupled Model Intercomparison Project Phase5 Global Climate Models (CMIP5 GCMs) downscaled by Coordinated Regional Downscaling Experiment (CORDEX) Rossby Centre’s regional Atmospheric model version 4, RCA4, to drive Ecocrop, a crop suitability model, for pearl millet, cassava, groundnut, cowpea, maize and plantain. The results show Ecocrop simulated crop suitability spatial representation with higher suitability, observed to the south of latitude 14°N and lower suitability to its north for 1971–2000 for all crops except for plantain (12°N). The model also simulates the best three planting months within the growing season from September-August over the past climate. Projected changes in crop suitability under the three GWLs 1.5–3.0 °C suggest a spatial suitability expansion for legume and cereal crops, notably in the central southern Sahel zone; root and tuber and plantain in the central Guinea-Savanna zone. In contrast, projected decreases in the crop suitability index value are predicted to the south of 14°N for cereals, root and tuber crops; nevertheless, the areas remain suitable for the crops. A delay of between 1-3 months is projected over the region during the planting month under the three GWLs for legumes, pearl millet and plantain. A two month delay in planting is projected in the south, notably over the Guinea and central Savanna zone with earlier planting of about three months in the Savanna-Sahel zones. The effect of GWL2.0 and GWL3.0 warming in comparison to GWL1.5 °C are more dramatic on cereals and root and tuber crops, especially cassava. All the projected changes in simulated crop suitability in response to climatic variables are statistically significant at 99% confidence level. There is also an increasing trend in the projected crop suitability change across the three warming except for cowpea. This study has implications for improving the resilience of crop production to climate changes, and more broadly, to food security in West Africa.
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Dessalegn, Obssi. "Propagation Methods of Yam (Dioscorea Species) with Special Attention to In Vitro Propagation." Journal of Applied Biotechnology 4, no. 1 (February 15, 2016): 13. http://dx.doi.org/10.5296/jab.v4i1.9031.
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<p>Yam is a monocotyledonous plant in the genus Dioscorea. It is a multi-species tuber crop cultivated in Africa, Asia and parts of South America. Yam is an important crop in South and Southwestern parts of Ethiopia. Many species of Dioscorea genus are economically important crops and many of them have been used in the pharmaceutical industry. Yam is propagated from seed tubers or sections of tuber and corms. Seed tubers are expensive, bulky to transport and the multiplication rate in the field is very low. Shortage of seed tubers for planting is one of the major constraints for yam production in Ethiopia. To overcome such problems and to increase production, different propagation methods have been implemented for many Dioscorea species. Convectional and In vitro propagation of Dioscorea species pave the way to meet the demand of this economically important plant. The protocols are designed to provide the optimal levels of mineral nutrients, environmental factors, vitamins and carbohydrates to achieve the high regeneration rate of the different species of Dioscorea in vitro. This review summarizes some of the important reports on different propagation technique of Dioscorea from the literature data.</p>
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Mansvelt, E. L., and E. Carstens. "Outbreak of Erwinia carotovora on Zantedischia spp. in South Africa." Plant Disease 83, no. 10 (October 1999): 966. http://dx.doi.org/10.1094/pdis.1999.83.10.966c.
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In South Africa, summer-flowering Arum lilies are grown for the tuber, potted plant, and cut flower markets. In 1998, an outbreak of soft rot was detected on Zantedischia oculata cv. Black Magic and Z. elliottiana plants from several nurseries. Crop losses of up to 25% were incurred. The initial symptom was wilting of leaves. When plants were lifted from the soil, soft rot of the tuber was found. Tuber rot usually developed on one side, and plants developing from affected tubers wilted and died. No discoloration of leaf or tuber tissues was found. Isolations from diseased tissues consistently yielded bacterial colonies that were translucent, white, and glistening and that had entire margins on nutrient agar. Ten representative isolates were chosen for further characterization. Erwinia carotovora subsp. carotovora strain B56 was included as a reference strain. All isolates were gram-negative rods, oxidase and arginine dihydrolase negative, catalase positive, and facultatively anaerobic. They degraded pectate and rotted potato slices but did not hydrolyze starch. All isolates fermented glucose, reduced nitrates to nitrites, and grew at a maximum temperature of 37°C. Isolates produced acids from D(+)-glucose, D(+)-cellobiose, melibiose, amygdalin, L(+)-arabinose, D-mannitol, L(+)-rhamnose, sucrose, ribose, D(-)xylose, and D(-)glucose but not from D-arabinose, D-sorbitol, or maltose. Isolates liquefied gelatin and used citrate, arbutine, esculin, salicin, and cellobiose as the sole carbon source. Pathogenicity to Zantedischia spp. was tested by injection of tubers with an inoculum suspension containing 108 CFU/ml. Control plants were inoculated with sterile distilled water. Inoculated plants were kept in a greenhouse at 24°C. Symptoms developed 2 days after inoculation with the pathogen and appeared to be identical to those observed on diseased material in nurseries. Control plants did not rot. The bacterium was readily reisolated from diseased plants, confirmed to be the inoculated pathogen, and identified as E. carotovora, based on morphological, biochemical, and physiological characteristics and pathogenicity. E. aroideae has been reported to cause soft rot of rhizomes of winter-flowering Arum lilies (Z. aethiopica) in South Africa (1). However, this is the first report of soft rot caused by E. carotovora subsp. carotovora on tubers of Z. oculata and Z. elliottiana plants in South Africa. Reference: (1) V. Wager. 1970. Flower Garden Diseases and Pests. Purnell, Cape Town, South Africa.
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Matthiessen, J. N., and S. E. Learmonth. "Impact of the soil insects African black beetle, Heteronychus arator (Coleoptera: Scarabaeidae) and Whitefringed weevil, Graphognathus leucoloma (Coleoptera: Curculionidae), on potatoes and effects of soil insecticide treatments in south-western Australia." Bulletin of Entomological Research 85, no. 1 (March 1995): 101–11. http://dx.doi.org/10.1017/s0007485300052068.
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AbstractPopulations of the soil insects African black beetle, Heteronychus arator (Fabricius), and whitefringed weevil, Graphognathus leucoloma (Boheman), and the damage caused to potato crops in south-western Australia were measured with and without the insecticide chlorpyrifos incorporated into the soil prior to planting. Low populations of both insects were highly damaging. Destruction of stems by H. arator reduced tuber yield and both species damaged tubers from the time of their formation. Tuber damage increased with time because both insect species on average damaged multiple tubers and caused multiple attacks on tubers. Growth of G. leucoloma larvae caused increased abundance of the more damaging later instars in spring. The insecticide reduced resident H. arator abundance and hence damage to newly-emerging potato stems in summer, but had less effect on reducing attacks on tubers in summer crops because adult beetles flew into some crops during growth. Exceptionally high tuber damage per H. arator adult in winter crops was ascribed to enhanced activity during its spring breeding season. The insecticide was inconsistent in reducing the abundance of G. leucoloma larvae. Insecticidal effects were greatest near the soil surface, resulting in an increase in the relative proportion of both insects deeper in the soil. Since a greater proportion of the tubers occurred there, the resulting greater potential for the insects to cause tuber damage tended to outweigh reduction in their abundance.
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Witbooi, Hildegard, L. Kambizi, and O. Oguntibeju. "An alternative health crop for South Africa: Purple potato mini tuber production as affected by water and nutrient stress." African Journal of Food, Agriculture, Nutrition and Development 20, no. 06 (October 31, 2020): 16818–31. http://dx.doi.org/10.18697/ajfand.94.19850.
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Food security in South Africa ranks as one of the top ten priorities in the country. Potato is a fundamental staple food crop in South Africa, providing essential nutrition. While there are several cultivars currently in production for the potato market, there is a need to explore cultivars that are available, but not utilised within the country. Pigmented potatoes are not regarded as high value on the South African market;however,yield prospects as well as health-promoting benefits could have a positive contribution on the South African Gross Domestic Product (GDP) and on the population’s health. Potato cultivar (cv.) Salad blue(SB)seems to be a drought-tolerant crop with the ability to produce reasonable yields under severe environmental conditions. In order to promote cv. SB as a possible food security option for South Africa, there is a critical need for empirical information, describing some basic horticultural as well as biochemical information and vitamin C presence. This study investigated the potential of pigmented potato SB tubers as an alternative to high yielding white potato for the South African market.Tubers of Solanum tuberosum cv. BP1 and SB, were used for this research.The high amounts in phenolic compounds in SB can be considered to be health-promoting phytochemicals. Anticarcinogenic, antibacterial, antiviral properties have been reported. A greenhouse, bag trial with virus-free plantlets of BP1 and SB cultivars was conducted using three water and nutrient levels and favourable root zone temperature(100% without heat, 100% heated, 50% heated, 25% heated) all grown in coco peat. Cultivar SB showed nearly two-fold yield compared to the control BP1. Methanol extracts of the tubers were assessed for their total polyphenolic, flavanol, and flavonol contents as well as 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, ferric reducing antioxidant power (FRAP), Trolox equivalence antioxidant capacity (TEAC),anthocyanin and L-ascorbic acid assays.The aqueous extract of the SB tubers was found to contain higher level of total polyphenols (320 mg GAE/g), and flavonol (85 mg QE/g) than the extract of the BP1 tubers with values of173 mg GAE/g (total polyphenol), and67 mg QE/g (flavonol). Similarly, the methanol extract of the tuber skins also exhibited higher DPPH (818,86 IC50mg/mL), FRAP (18,19μmol AAE/g), and TEAC (911,12μmol TE/g)than the extract of the BP1with DPPH (595,99 IC50mg/mL), FRAP (10,86 μmol AAE/g) and TEAC (435,44 μmol TE/g). The present study provides useful information for farmers and health professionals in respect to increased yield and health-promoting benefits of an underutilized potato variety.
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Muzhinji, Norman, and Jacquie E. van der Waals. "Population Biology and Genetic Variation ofSpongospora subterraneaf. sp.subterranea, the Causal Pathogen of Powdery Scab and Root Galls on Potatoes in South Africa." Phytopathology® 109, no. 11 (November 2019): 1957–65. http://dx.doi.org/10.1094/phyto-12-18-0467-r.
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Spongospora subterranea f. sp. subterranea, causal agent of powdery scab and root galls of potatoes, occurs worldwide and is responsible for quality and yield losses in potato production in South Africa. Despite being one of the most important potato pathogens in South Africa, little information is available on the genetic structure and diversity of S. subterranea f. sp. subterranea, which could provide insight into the factors shaping its evolution and the role of inoculum sources in disease development. A total of 172 samples were collected from four potato growing regions in South Africa. An additional 27 samples obtained from Colombia were included for comparative purposes. The samples were screened against six informative microsatellite (simple-sequence repeat) markers. Of the 172 samples obtained from potato growing regions in South Africa, there were 75 multilocus genotypes (MLGs), only 16 of which were shared between potato growing regions, indicating substantial gene flow and countrywide dispersal of the pathogen. The presence of common MLGs among the root- and tuber-derived samples indicated a lack of specialization of S. subterranea f. sp. subterranea to either tuber or root infection. Nei’s unbiased estimates of gene diversity for the clone-corrected data were low and ranged from 0.24 to 0.38. Analysis of molecular variance and discriminant analysis of principal components showed no population differentiation between different potato growing regions in South Africa and between root- and tuber-derived genotypes. The presence of MLGs, high considerable genotypic diversity, and failure to reject the null hypothesis of random mating in most populations are indicative of some kind of recombination, either sexual or asexual, in these S. subterranea f. sp. subterranea populations. Information from this study provides new insights into the genetic structure and diversity of S. subterranea f. sp. subterranea in South Africa. Continuous monitoring of the pathogen population dynamics will be helpful in implementing effective region-specific management strategies for the pathogen, especially in the development of resistant potato cultivars.
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Gouws, R., and A. McLeod. "Fissure Scab, a New Symptom Associated with Potato Common Scab Caused by a Streptomyces sp. in South Africa." Plant Disease 96, no. 8 (August 2012): 1223. http://dx.doi.org/10.1094/pdis-12-11-1056-pdn.
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Common scab caused by Streptomyces spp. is one of the major factors limiting successful potato (Solanum tuberosum) production in South Africa. Most potato cultivars are susceptible to the disease and huge losses are incurred due to a reduction in cosmetic value. Common scab symptoms that have been reported worldwide are variable, with circular, raised, tan-to-brown, corky lesions being the most common symptoms. However, a distinct atypical symptom was observed in isolated production regions (Western Free State and Mpumalanga) in South Africa since early 2010. Deep longitudinal fissures (3 to 12 mm) containing scab-like lesions were observed on the surface area of tubers from several potato cultivars (Mondial, BP1, and Buffelspoort). Lesions on Mondial were interesting since this cultivar, but not the susceptible BP1 and Buffelspoort cultivars, is tolerant to typical common scab in South Africa. Isolations were made from tuber lesions obtained from the two production regions and were plated onto yeast malt extract medium. Several pure culture strains were obtained that were positively identified as Streptomyces spp. based on morphology. Species identity of four strains was investigated using PCR primers targeting the 16S rRNA region of known species (3), which showed that the strains did not belong to any of the known pathogenic reference strains (S. scabiei, S. europascabiei, S. turgidiscabies, S. acidiscabies). Species identity of the strains was further investigated through sequencing of the 16S rRNA region (1.2 kb). The four strains had 100% sequence similarity (GenBank Accession. No. JQ241439) to each other and to 15 GenBank sequences that included several unknown Streptomyces spp., S. vinaceus, S. malachiticus, S. werraensis, S. cyaneus (the only published sequenced), and S. pseudogriseolus. The sequence of the isolates had only 95.5% identity to the most prevalent common scab pathogen, S. scabiei (GI154707840, [3]). The pathogenicity of the four strains, along with an S. scabiei reference isolate, was investigated using BP1 potato tubers and the double pot methodology (1). Fifteen-centimeter pots containing silica sand were each planted with one potato tuber and placed on top of a rectangular planting box (15 × 1.5 × 0.4 m) filled with native Hutton soil. The 15-cm pots were irrigated until the roots grew into the Hutton soil. Subsequently, irrigation was only applied to the Hutton soil, thus creating dry conditions in the tuber development area (15-cm pot), which is conducive for common scab development. The potato plants were inoculated with 10- to 14-day-old Streptomyces strains during the tuber initiation stage at a concentration of 1 × 106 spores/ml of sterile water, 10 ml per plant, and six replicates per strain. Ten weeks after inoculation, each of the four strains caused cracking and scabbing, similar to initial symptoms observed, on more than 90% of the tubers. The S. scabiei reference isolate caused typical circular, raised, brown, corky common scab lesions. Streptomyces was reisolated from the lesions, fulfilling Koch's postulates. To our knowledge, these results indicate that a previously unreported Streptomyces sp. is the causal agent of a new lesion type, fissure scab, on potato in South Africa that may lead to serious losses to the local potato industry. References: (1) L. Marais and R. Vorster. Potato Res. 31:401, 1988. (2) D. J. Theron. Page 1 in: Guide to Potato Production in South Africa, 2003. (3) L. Wanner. Phytopathology 96:1363, 2006.
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Muzhinji, N., J. W. Woodhall, M. Truter, and J. E. van der Waals. "Elephant Hide and Growth Cracking on Potato Tubers Caused by Rhizoctonia solani AG3-PT in South Africa." Plant Disease 98, no. 4 (April 2014): 570. http://dx.doi.org/10.1094/pdis-08-13-0815-pdn.
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Rhizoctonia solani consists of 13 anastomosis groups (AGs) designated AG1 to 13. AG3-PT is considered the predominant AG in potatoes (4) and is associated with quantitative and qualitative yield losses. Qualitative losses are typically associated with the tuber blemish disease, black scurf. However, atypical tuber blemishes such as elephant hide consisting of corky lesions on the tuber surface (2) have also been attributed to Rhizoctonia. Such atypical blemishes are not considered specific to Rhizoctonia, making direct-cause effect estimates difficult (1). Koch's postulates for the elephant hide symptom and R. solani AG3-PT have not been completed. Recently, growth cracking and scab lesions were observed on potato tubers in South Africa and attributed to a new Streptomyces species (3). These lesions and cracks were similar to elephant hide symptoms attributed to R. solani AG3-PT. Therefore, the cause of the elephant hide symptom in South Africa was investigated further. Symptoms of elephant hide and cracking have been observed on tubers from the Eastern Free State, KwaZulu-Natal, Limpopo, Mpumalanga, North-Eastern Cape, Northern Cape, North West, Sandveld, and Western Free State growing regions. In 2012, three samples of potato tubers (cv. BP1) with elephant hide and cracking were selected for analysis. These samples were collected from Clanwilliam in the Sandveld potato growing region. Tubers were surface sterilized with 1% NaOCl; sections of affected tissue were excised and plated onto potato dextrose agar (PDA). Rhizoctonia-like colonies were identified and after further sub-culturing on PDA, three representative isolates (Rh3, Rh4, and Rh6) of R. solani from each sample were obtained. For each isolate, genomic DNA was extracted and the rDNA ITS region sequenced using ITS1-F and ITS4 (2). The resulting sequences (KF234142, KF234143, and KF234144) were at least 98% identical to other AG3-PT sequences on GenBank (JX27814 and KC157664). To confirm Koch's postulates, pathogenicity tests were conducted with the three isolates. PDA plugs of each isolate were added to 10 g of barley grains which were incubated for 14 days until fully colonized. The barley grains were then used to inoculate disease-free mini-tubers (cv. BP1) in 5l pots containing a sand-clay-pine bark mixture (1:1:1 ratio). Potato plants inoculated with sterile barley grains served as controls. Plants were held for 120 days in a greenhouse at 22°C with light for 12 h a day. Incidence of the elephant hide symptom for isolates Rh3, Rh4, and Rh6 was 58%, 33%, and 37.5%, respectively. Growth cracking and black scurf were also observed with each isolate. R. solani AG3-PT was successfully re-isolated from symptomatic tubers, confirming Koch's postulates. This is the first report of R. solani AG3-PT causing elephant hide in potato tubers in South Africa. Elephant hide caused by R. solani AG3-PT has been reported in tubers from France (2) and the United Kingdom (3), but Koch's postulates were not proven. In this study, Koch's postulates were proven for R. solani AG3-PT causing scab or elephant hide symptom and cracking in potato tubers. R. solani AG3-PT should thus be considered in addition to Streptomyces as a cause of this symptom and control strategies should also consider R. solani AG3-PT. References: (1) G. J. Banville et al. Pages 321-330 in: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control, B. Sneh et al., eds. Kluwer Academic Publishers, Dordrecht, The Netherlands, 1996. (2) M. Fiers et al. Eur. J. Plant. Pathol. 128:353, 2010. (3) R. Gouws and A. McLeod. Plant Dis. 96:1223, 2012. (4) J. W. Woodhall et al. Eur. J. Plant. Pathol. 136:273, 2013.
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Zarka, Kelly A., Ria Greyling, Inge Gazendam, Dean Olefse, Kimberly Felcher, Gurling Bothma, Johan Brink, Hector Quemada, and David S. Douches. "Insertion and Characterization of the cry1Ia1 Gene in the Potato Cultivar Spunta for Resistance to Potato Tuber Moth." Journal of the American Society for Horticultural Science 135, no. 4 (July 2010): 317–24. http://dx.doi.org/10.21273/jashs.135.4.317.
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Potato tuber moth (Phthorimaea operculella) is a serious pest of potatoes in tropical and subtropical regions of the world, including South Africa. The cry1Ia1 gene (from Bacillus thuringiensis) under the control of the 35S cauliflower mosaic virus promoter was transformed into the potato (Solanum tuberosum) cultivar Spunta to develop a cultivar with resistance to potato tuber moth for release in South Africa. Two transformation events, ‘SpuntaG2’ and ‘SpuntaG3’, were selected and subjected to extensive molecular analyses as required by the regulatory agencies of South Africa. Southern hybridization experiments indicated that ‘SpuntaG2’ and ‘SpuntaG3’ had one and three copies of the cry1Ia1 gene, respectively, and that the gene insertion was stable through multiple clonal generations. Furthermore, the sequence of the cry1Ia1 gene in ‘SpuntaG2’ was compared with the known sequence of the cry1Ia1 gene and found to be identical. Polymerase chain reaction (PCR) amplification using primers for plasmid “backbone” genes demonstrated that ‘SpuntaG2’ contained no backbone plasmid genes, whereas ‘SpuntaG3’ contained several backbone plasmid genes. Therefore, further analyses were limited to ‘SpuntaG2’, and event-specific primers were developed for this cultivar. Analysis of the left and right border regions in ‘SpuntaG2’ demonstrated that the insertion of the cry1Ia1 gene did not disrupt any functional genes nor did it create new open reading frames that encoded proteins with a significant match to the non-redundant sequence database queried by the BLASTP program. Enzyme-linked immunoabsorbent assays (ELISA) tests indicate that the cry1Ia1 gene was expressed at a mean concentration of 2.24 μg·g−1 fresh weight in leaf tissue and 0.12 μg·g−1 fresh weight in tubers. This study demonstrates the extensive molecular characterization that is necessary to apply for deregulation of a genetically modified crop and these data have been used in a regulatory package for the general release of ‘SpuntaG2’.
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Muzhinji, N., J. W. Woodhall, M. Truter, and J. E. van der Waals. "First Report of Rhizoctonia solani AG 4HG-III Causing Potato Stem Canker in South Africa." Plant Disease 98, no. 6 (June 2014): 853. http://dx.doi.org/10.1094/pdis-11-13-1131-pdn.
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Black scurf and stem canker caused by Rhizoctonia solani Kühn (teleomorph: Thanathephorus cucumeris Frank Donk) are potato diseases of worldwide economic importance (4). R. solani consists of 13 anastomosis groups (AGs) of which AG 3-PT is considered the dominant causal agent of potato diseases globally (1,4). However, other AGs such as AG 2-1, 5, and 8 have been reported to cause potato diseases (1,4). In February 2013, potato stem samples (cv. Mondial) displaying dark brown lesions resembling those caused by Rhizoctonia stem canker were obtained from a commercial field in Limpopo Province, South Africa. Symptomatic tissue was disinfected with 1% NaOCl for 1 min, rinsed in sterile water, and 4-mm stem pieces excised from the margins of symptomatic tissues and plated on 2% water agar supplemented with 20 mg/l of chloramphenicol. Single hyphal tips taken from fungal isolates identified as R. solani based on morphological traits (3) were transferred to potato dextrose agar. DNA was isolated from the resulting cultures and ITS region of rDNA was sequenced as previously described (2). The resulting sequences of three of the isolates, Rh 81, Rh 82, and Rh 83 (KF712285, KF712286, and KF712287), were 99% similar to those of AG 4 HG-III found in GenBank (DQ102449 and AF354077). Therefore, based on molecular methods, these three isolates were identified as R. solani AG4 HG-III. To determine pathogenicity of the AG4 HG-III isolates, certified disease free mini-tubers (Generation 0, cv. Mondial, produced in tunnels) were used in pot trials. PDA plugs of each isolate were added to 10 g of barley grains, which had been sterilized by autoclaving for two consecutive days at 121°C for 30 min, and were incubated for 14 days until fully colonized. Ten colonized barley grains were placed 10 mm above each mini-tuber planted in 5l pots containing sterile potting mixture of sand:clay:pinebark (1:1:1). Ten tubers were inoculated with each isolate. Uninoculated, sterile barley grains were applied to the control treatment. Mini-tubers were grown in a greenhouse maintained at 22°C with light for a 12 h day. After 7 weeks, five plants for each isolate were destructively sampled and assessed for stem canker symptoms. At 120 days after sowing, the remaining five plants per treatment were assessed for blemishes on progeny tubers. The stem canker incidences of plants inoculated with Rh 81, Rh 82, and Rh 83 were 25, 25, and 50%, respectively, whereas no symptoms were observed in control plants. Sclerotia formation and blemishes were not observed on any of the progeny tubers, which might indicate that these strains are only able to infect stems, or that environmental conditions were not suitable for tuber blemish or black scurf development. R. solani AG4 HG-III was consistently re-isolated from symptomatic stems displaying brown lesions, and the identity of the re-isolates were confirmed by molecular tests as previously described, thereby fulfilling Koch's postulates. To our knowledge, this is the first report of R. solani AG4 HG-III causing stem canker on potato in South Africa and worldwide. Knowledge of which AGs are present in crop production systems is important when considering disease management strategies such as crop rotation and fungicide treatments (3). References: (1) C. Campion et al. Eur. J. Plant. Pathol. 109:983, 2003. (2) N. Muzhinji et al. Plant Dis. 98:570, 2014. (3) L. Tsror. J. Phytopathol. 158:649, 2010. (4) J. W. Woodhall et al. Plant. Pathol. 56:286, 2007.
Dissertations / Theses on the topic "Tuber crops south africa"
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Brand, Mariette Rieks. "Pollination ecosystem services to onion hybrid seed crops in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86238.
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Thesis (PhD)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Insect pollination contributes in various degrees toward the production of a variety of agricultural crops that ensure diversity and nutritional value in the human diet. Although managed honeybees (Apis mellifera L.) are still the most economically valuable pollinators of monoculture crops cultivated globally, wild pollinator communities can contribute substantially toward crop pollination through pollination ecosystem services sourced from neighbouring natural habitats. Pollination ecosystem services are thus valuable and can motivate for the protection of natural ecosystems hosting diverse insect pollinator communities. F1 onion hybrid seed production is entirely dependent on high insect pollinator activity to ensure cross pollination, seed set and profitable seed yields. Data was collected on 18 onion hybrid seed crops grown in the semi‐arid Klein Karoo and southern Karoo regions of the Western Cape, South Africa. These two main production regions are located within the Succulent Karoo biome, recognized as a global biodiversity hotspot of especially high plant diversity. It is also habitat to the indigenous Cape honeybee (Apis mellifera capensis Esch.). Sites selected varied in the percentages of available natural habitat and managed honeybee hives stocking density. Diverse anthophile assemblages were sampled with pan traps within all the onion fields, regardless of the percentage of available natural habitat near the crop. Crop management practices significantly affected the diversity of anthophile species caught within onion fields, although less than 20% of this diversity was observed actually visiting onion flowers. The honeybee (managed and wild) was by far the most important pollinator because of its high visitation frequency and regular substantial onion pollen loads carried on their bodies. Honeybee visitation significantly increased onion hybrid seed yield, while anthophile diversity and non‐Apis visitation had no effect on seed yield. Neither managed hive density, nor percentage natural habitat were important in determining honeybee visitation or seed yield. Total annual rainfall was the only significant factor determining honeybee visitation. Secondary factors caused by rainfall variability, such as wild flower abundance or soil moisture, may have significantly affected honeybee visitation. In addition, the positive correlation between honeybee visitation and the diversity of hand‐sampled insects from onion flowers; indicate that either or both onion varietal attractiveness and/or pollinator population size may have had significant effects on overall insect visitation. Honeybees showed marked discrimination between hybrid onion parental lines and preferred to forage on one or the other during single foraging trips. Hybrid onion parents differed significantly in nectar characteristics and onion flower scent which would encourage selective foraging through floral constancy. Interspecies interactions were insignificant in causing increased honeybee pollination because of the scarcity of non‐Apis visitors. Most farming practices are subjected to favourable environmental conditions for successful production. However, and especially in the South African context, the dependence of onion hybrid seed crops on insect pollination for successful yields, increase its reliance on natural ecosystem dynamics that may deliver abundant wild honeybee pollinators, or attract them away from the crops. Nevertheless, this dependence can be mitigated effectively by the use of managed honeybee colonies to supplement wild honeybee workers on the flowers.
AFRIKAANSE OPSOMMING: Insek bestuiwing dra in verskillende grade by tot die produksie van landbou gewasse wat variteit en voedingswaarde in die mens se dieet verseker. Al is die heuningby (Apis mellifera L.) steeds die waardevolste ekonomiese bestuiwer van verboude enkelgewasse, kan wilde bestuiwers wesenlik bydra tot gewasbestuiwing deur middel van ekosisteem dienste afkomstig van natuurlike habitatte. Bestuiwing ekosisteem dienste is daarom waardevol en kan dus die bewaring van natuurlike ekosisteme, wat diverse gemeenskappe huisves, regverdig. F1 basterui saadproduksie is totaal afhanklik van hoë insek‐bestuiwer aktiwiteit om kruisbestuiwing, saadvorming en winsgewende saadopbrengste te verseker. Data is ingesamel op 18 basterui saad aanplantings in die half‐droë Klein Karoo en suid‐Karoo streke van die Weskaap, Suid‐Afrika. Hierdie twee hoof produksie streke is geleë binne die Sukkulente Karoo bioom wat erken word as ʼn globale biodiversiteits “hotspot” met hoë plant diversiteit. Dit is ook die habitat van die inheemse Kaapse heuningby (Apis mellifera capensis Esch.). Aanplantings is gekies om verskillende grade van beskikbare natuurlike habitat en bestuurde heuningby korf digthede te verteenwoordig. Diverse versamelings blom‐besoekers is versamel met water‐wippe in al die aanplantings, ongeag die persentasie natuurlike habitat beskikbaar by elke aanplanting. Gewas bestuurspraktyke het die diversiteit van blombesoekers betekenisvol beïnvloed. Tog is minder as 20% van hierdie diversiteit as aktiewe besoekers op die uiekoppe waargeneem. Heuningbye (bestuur of wild) was oorwegend die belangrikste bestuiwers as gevolg van hoë besoek frekwensies en wesenlike ladings uiestuifmeel op hulle liggame. Heuningby besoeke het saadopbrengs betekenisvol verhoog, maar blom‐besoeker diversiteit en nie‐Apis besoeke het geen effek op saadopbrengs gehad nie. Bestuurde korf digtheid en persentasie natuurlike habitat was nie belangrik in die bepaling van heuningby besoeke of basterui saadopbrengste nie. Totale jaarlikse reënval was die enigste betekenisvolle faktor wat heuningby besoeke bepaal het. Sekondêre faktore wat versoorsaak word deur reënval veranderlikheid, soos veldblom volopheid of grondvog, kon betekenisvolle effekte op die aantal heuningby besoeke gehad het. Bykomend, dui die positiewe korrelasie tussen heuningby besoeke en die diversiteit van hand‐versamelde insekte vanaf die uiekoppe op die moontlike betekenisvolle effek van elk of beide basterui variteit aantreklikheid en/of bestuiwer populasie grote op algehele insek besoeke. Heuningbye het noemenswaardige diskriminasie getoon tussen die basterui ouerlyne en het verkies om op een of die ander te wei tydens enkele weidingstogte. Basterui ouerlyne het betekenisvol verskil in nektar eienskappe en blomgeur wat die selektiewe weiding van heuningbye, toegepas deur blomkonstantheid, sal aanmoedig. Tussen‐spesie interaksies was onbetekenisvol in die verhoging van heuningby bestuiwing omdat nie‐Apis besoekers baie skaars was. Meeste boerdery praktyke is onderhewig aan gunstige omgewings toestande vir suksesvolle produksie. Maar, en veral in die Suid‐Afrikaanse konteks, omdat basterui saad aanplantings afhanklik is van insek bestuiwing vir suksesvolle opbrengste, word daar meer staat gemaak op natuurlike ekosisteem dinamika wat volop wilde heuningby bestuiwers kan voorsien, of selfs bestuiwers van die aanplanting kan weg lok. Nietemin, hierdie afhanklikheid kan effektief verlaag word deur die gebruik van bestuurde heuningby kolonies om die aantal wilde heuningby werkers op die blomme aan te vul.
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Sheldon, Bonita Joy. "Heavy metal uptake and accumulation in agricultural crops in urban areas of the Western Cape." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/2006.
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Thesis (MTech (Physical Sciences))--Cape Peninsula University of Technology, 2005.A research study into heavy metals in the Cape Town area, found significant amounts of potentially toxic metals such as lead, cadmium, chromium and iron leaching into the underground aquifer. A further additional study conducted on a community garden in Khayelitsha, showed that vegetable crops have the tendency to accumulate certain heavy metals if they are present in soil and water resources. This study was centered around the Philippi Horticultural Area, which is a large significant farming area within the Cape Metropolitan Region. The significance of the study lies in the fact that at least 50% of the local farmers' produce is sold directly to street traders, residents, local supermarket-chains and restaurants. The remainder of the produce is sold at the Epping Market. The purpose of this study was to investigate heavy metal accumulation in various vegetable crop species taken from some of the local farms in the Phillipi Farming area with the objective to: • investigate heavy metal accumulation in various vegetable crop species taken from some local farms in the Phillipi Farming area. • determine the concentrations of heavy metals present in water and soil resource since these will be the primary source of heavy metals to the vegetables. • determine the soil pH and soil organic matter as these two factors would determine the bie-availability ofthe heavy metals. • identify those crops that pose a definite health risk by means of comparing the determined results to the allowed limits.
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Rentel, Monique. "Morphology and taxonomy of tortricid moth pests attacking fruit crops in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79825.
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Thesis (MScAgric)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Cydia pomonella (codling moth), Thaumatotibia leucotreta (False codling moth), Thaumatotibia batrachopa (Macadamia nut borer), Grapholita molesta (Oriental fruit moth), Cryptophlebia peltastica (Litchi moth), Epichoristodes acerbella (Pear leafroller/Carnation worm) and Lozotaenia capensana (Apple leafroller) are the most economically important tortricids affecting various crops in South Africa. The correct identification of these species, especially of the larval stage, is of great importance in pest management. Using available literature, augmented by additional morphological studies, an interactive identification key (Lucid key) for larval and adult stages of the seven species was developed. The colour and markings of the head, characteristics of the prothoracic and anal shields, the position of the prespiracular setae (L-group) relative to the spiracle on the prothoracic segment, the position of the spiracle on the eighth abdominal segment and L-group on the ninth abdominal segment, as well as the presence or absence of the anal comb are key characteristics for larval identification. For adult identification, wing pattern and genitalia are the most important features. However, the use of genitalia for moth identification might be difficult for the lay user, as the dissection and mounting of these structures requires certain skills and specialized equipment. Thus, genitalia have not been included in the Lucid Key. Differences in the morphological characteristics of most pupae were so minute that this stage was also not included in the Lucid key. However, the pupae of E. acerbella and L. capensana are easily distinguished from those of the other species by the presence of acremaster. This study also included the first morphological description of the pupa of L. capensana, which can be distinguished from that of E. acerbella by various features of the cremaster, antennae, spiracle shape, number of setae on abdominal segments A5-7, the size of spines on A3-7, and the presence/absence of spines on A9. A previous study by Timm (2005) indicated that geographically isolated populations of T. leucotreta tend to be genetically distinct. This raised the question of whether speciation/subspeciation has occurred or is occurring. Male moth genitalia are thought to evolve rapidly and are often the only features that can reliably distinguish similar species. Hence, variation in the shape of the valvae of T. leucotreta was used to determine whether divergence has occurred between populations of T. leucotreta. Elliptical Fourier analysis was used to analyze the valvar variation in three different populations. Although some variation in valvar shape was detected among mean population values for certain traits, no clear pattern emerged. Principle component analysis also showed no distinct clustering of valvae shape among populations, providing no evidence for divergence in male genitalia and therefore no morphological evidence of incipient speciation.
AFRIKAANSE OPSOMMING: Cydia pomonella (Kodlingmot), Thaumatotibia leucotreta (Valskodlingmot), T. batrachopa (Makadamianeutboorder), Grapholita molesta (Oosterse vrugtemot), Cryptophlebia peltastica (Lietsjiemot), Epichoristodes acerbella (Peerbladroller/Angelierrusper) en Lozotaenia capensana (Appelbladroller) is die mees ekonomies belangrike tortrisiede van die vrugtebedryf in Suid-Afrika. Die juiste identifikasie van hierdie spesies, veral van hulle larwale stadium, is van groot belang by plaagbestuur. Deur gebruik te maak van beskikbare literatuur, aangevul deur bykomstige morfologiese studies, is ‗n interaktiewe uitkenningssleutel (―Lucid key‖) vir die larwale en volwasse stadia van die sewe spesies ontwikkel. Die kleur en tekening van die kop, kenmerke van die prothorakale en anale skild, die ligging van die prespirakulêre setae (L-groep) relatief tot die spiraculum op die prothorakale segment, die ligging van die spirakulum op die agste abdominale segment en L-groep op die negende abdominale segment, asook die aan- of afwesigheid van die anale kam is sleutel kenmerke vir larwale uitkenning. Vir die volwassenes is die vlerktekening en genitalia die mees belangrike kenmerke. Die gebruik van die genitalia vir motuitkenning kan egter vir die leek gebruiker moeilik wees omdat die disseksie en montering van hierdie strukture bepaalde vaardighede en gespesialiseerde toerusting vereis. Vir die rede is die genitalia nie in die Lucid-sleutel ingesluit nie. Verskille in die morfologiese kenmerke van meeste papies is klein en die stadium is gevolglik ook nie in die sleutel ingesluit nie. Die papies van E. acerbella en L. capensana kan egter maklik van die ander spesies onderskei word deur die aanwesigheid van ‗n cremaster. Hierdie studie sluit ook die eerste morfologiese beskrywing van die papie van L. capensana in, wat van dié van E. acerbella onderskei kan word deur gebruik te maak van kenmerke van die cremaster, antennae, spirakulêre vorm, aantal setae op abdominale segmente A5-7, die grootte van stekels op A3-7, en die aan- of afwesigheid van stekels op A9. ‗n Vroeëre studie (Timm 2005) het aangedui dat geografies geïsoleerde bevolkings van T. leucotreta neig om geneties verskillend te wees. Dit het die vraag laat ontstaan of spesiasie/subspesiasie moontlik plaasgevind het of steeds plaasvind. Manlike mot genitalië word geag om vinnig te ontwikkel en is dikwels die enigste kenmerke wat betroubaar tussen soortgelyke spesies kan onderskei. Dus is die variasie in die vorm van die valvae van T. leucotreta gebruik om te bepaal of divergensie wel tussen bevolkings van T. leucotreta plaasgevind het. Elliptiese Fourier ontleding is gebruik om die valvae se variasie by drie verskillende bevolkings te ontleed. Alhoewel enkele variasie in die vorm van die valvae bespeur is by die gemiddelde bevolkingswaardes vir bepaalde eienskappe, kon geen duidelike patroon bespeur word nie. Hoofkomponentontleding het ook geen duidelike groepering van valvae se vorm tussen bevolkings getoon nie, wat geen bewys lewer van divergensie in die manlike genitalia en dus geen morfologiese bewys van beginnende spesiasie.
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Manamathela, Sibongile Amelia. "The water footprint of selected crops within the Olifants/Doorn Catchment, South Africa." University of the Western Cape, 2014. http://hdl.handle.net/11394/4751.
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>Magister Scientiae - MScRapidly increasing global population is adding more pressure to the agricultural sector to produce more food to meet growing demands. However the sector is already faced with a challenge to reduce freshwater utilisation as this sector is currently using approximately 70% of global water freshwater resources. In South Africa, the agriculture sector utilizes approximately 62% of freshwater resources and contributes directly about5% to the Gross Domestic Product. South Africa is a water scarce country receiving less than 500mm/year of precipitation in most parts of the country, and consequently approximately 90% of the crops are grown under irrigation. Studies have evaluated irrigation practices and crop water use in the country. However information is lacking on the full impact of South African horticultural products on freshwater resources. The water footprint concept can be used to indicate the total and source (blue/green) of water used to produce the crops. Information about water footprint (WF) can be used for identifying opportunities to reduce the water consumption associated with production of vegetables and fruits at the field to farm- gate levels, including the more effective use of rainfall (green water) as opposed to water abstracted from rivers and groundwater (Blue water). It can also be used to understand water related risks associated with the production of crops and facilitate water allocation and management at catchment/water management scale. While the potential value of water footprint information is well recognized there is still inadequate knowledge on how best to determine the water footprints of various crops within a local context. The aim of this study was to determine the water footprint and the crop water productivity of navel oranges, pink lady apples and potatoes produced with the Olifant/Doorn water management area in South Africa.The water footprint of the navel oranges, pink lady apples and potatoes assessed following the water footprint network method was 125 litres/ kg, 108 litres/kg and 65 litres/ kg respectively. The study concluded that water footprint studies should be carried out on the whole catchment instead of one farm in order to assess the sustainability of the process.
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Morgan, John (John Idwal). "Evaluating the returns to research on a project level : cover crops in the South African wine industry." Thesis, Stellenbosch : Stellenbosch University, 1999. http://hdl.handle.net/10019.1/51261.
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Thesis (MScAgric)--Stellenbosch University, 1999.ENGLISH ABSTRACT: The purpose of the study is to determine the rate of return to cover crop research in the wine industry. The method followed will prove an invaluable contribution toward the need to determine a suitable approach for evaluation studies. The importance behind such a study is the development of appropriate ex ante evaluation approaches, which will assist in the allocation of public research resources in both a social and economical manner. The wine industry is currently enjoying healthy international demand, but will need to remain competitive to reap the full benefit of international exposure. The need therefore exists for a continuation of research at the institutional level, in order to maintain the progressive nature of research knowledge that was available in the past. The evaluation of ex post and ex ante research will assist in maintaining government funding for research and help with campaigning for private investment of research in the wine industry. The use of two evaluation approaches was used for the analysis. Firstly, the production function approach achieved a rate of return of 44 percent, using weather and research expenditure as a means to explain the variations in wine grape yield. Secondly, a cost benefit approach was devised in order to make a direct comparison between the cost and benefits related to the cover crop research. The rate of return achieved for this mode of analysis is 37 percent, using trial plot data as a source of information on potential benefits. In addition to this the cost benefit approach was used to show the difference in rate of return that is achievable between two growing regions. The variable that exists between the two regions, is the higher rate of irrigation in one of the regions. The high rate of return achieved for the investment, provides suitable motivation for the increase in state funding for research in the wine industry, and provides valuable information for the enticement of support by private investors. The two methods used in the study will both draw a certain amount of criticism, largely as a result of the lack of available data. The empirical nature of the approaches is however simple and applicable down to the project level.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die opbrengs op navorsing oor dekgewasse in die Suid- Afrikaanse wynbedryf te bepaal. Hierbenewens het die studie dit ook ten doel om gepaste metodieke vir die evaluering van navorsingsprojekte daar te stel. In hierdie opsig maak hierdie studie ' n bydrae tot besluitneming oor die allokering van openbare fondse vir landbounavorsing op 'n ekonomies en sosiale optimale wyse. Die Suid- Afrikaanse wynbedryf beleef tans ' n bloeifase, hoofsaaklik as gevolg van sterk internasionale vraag na sy produkte, maar salop sy internasionale mededingendheid moet let indien die volle voordele hiervan benut kan word. Daarom is dit noodsaaklik dat die bedryf op tegnologiese gebied moet kan meeding, en dus dat navorsingsbesteding nie onoordeelkundig ingekort word rue. Inligting oor die opbrengs op navorsingsbesteding is dus noodsaaklik om die volgehoue betrokkenheid van die staat te kan regverdig, hetsy as finansier of as katalisator vir privaatsektor betrokkenheid. In hierdie studie is die opbrengs op navorsing gemeet deur beide die bekende produksiefunksie benadering sowel as deur koste-voordeel ontleding. In die eerste geval is 'n opbrengskoers van 44% gemeet, en in die tweede geval is dit 37%. By die kostevoordeel ontleding is ook 'n verdere onderskeid gemaak tussen twee wynbou-streke om die invloed van meer besproeiing te bepaal. Ten spyte van dataprobleme, veral wat betref die koste van navorsing, kan beweer word dat die inligting so verkry van nut sal wees vir besluitnemers by die toekenning van skaars navorsingsfondse, asook by bedinging om privaatsektor fondse.
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Maali, Safiah Hasan. "Biomass production, yield and quality response of spring wheat to soil tillage, crop rotation and nitrogen fertilisation in the Swartland wheat producing area of South Africa." Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/949.
Full textAbstract:
Thesis (PhD(Agric) (Agronomy))--University of Stellenbosch, 2003.108 leaves printed on single pages, preliminary pages i-vi and numbered pages 1-1 to 1-5 to 9-1 to 9-3. Includes bibliography, list of abbreviations and 22 figures in color. Digitized at 300 dpi grayscale and 300 dpi 24-bit Color to pdf format (OCR), using an HP Scanjet 8250 Scanner.
ENGLISH ABSTRACT: A long term experiment was conducted at the Langgewens Experimental Farm, near Malmesbury in the Western Cape province of the Republic of South Africa. The effect of soil tillage, crop rotation and nitrogen fertiliser rates on mineral-N levels in the soil, nitrogen levels in plants, wheat growth and yield components, grain yield as well as quality parameters of spring wheat were determined. Although the tillage treatments tested were initiated in 1976, present crop rotations and nitrogen application rates were only applied since 1990. Most of the data that are discussed however was recorded during the 1997 to 2001 period. The trial was designed as a randomised complete block with a split-plot arrangement and four replicates. Main plots were tillage methods namely conventional tillage (CT), tine tillage (TT), minimum tillage (MT) and no tillage (NT). Crop rotations used were continuous wheat (WW) and wheatl lupin/wheat/canola (WLWC). Both soil and crop data were recorded. The results of this study showed the differences in total mineral-N content of the soil. N-contents of wheat, wheat growth and yield components as well as wheat quality parameters were found between tillage treatments, crop rotations used as well as N- fertiliser rates applied. Response however, varied largely between years due to annual variation in especially total precipitation and distribution of rainfall. The inclusion of a legume crop (lupin) and canola in the rotation with wheat was found to have only a small effect probably due to the fact that lupins were grown once in a four year cycle only. Application of different nitrogen rates did increase the mineral-N in the soil, but the effect did not last very long in most years due to either N-leaching or plant uptake. To ensure sufficient mineral-N levels, late application of N-fertiliser will therefore be needed. Minimum tillage or reduced tillage performs better than conventional tillage in low rainfall years. In general these tillage systems should be combined with crop rotation to ensure that yields are comparable to that obtained with conventional tillage.
AFRIKAANSE OPSOMMING: Die ontwikkeling, graanopbrengs en bakkwaliteit van koring (Tritium aestivum L.) in reaksie teenoor gewasratasie, metode van grondbewerking en N-bemestingspeil is in 'n lang tennyn sllldie op Langgewens Proefplaas, naby Malmesbury in die Weskaap provinsie van die Republiek van Suid-Afrika, bepaal. Hoewel die verskillende grand bewcrkingsmetodes sedert 1976, en gewasrotasies en slikstofpeile sedert 1990 toegepas is, is daar in hierdie studie gekonsentreer op data wal gcdurcnde die periode 1997-2001 ingesamel is. Die eksperiment is as 'n randomiseerde blok ontwerp met vier bewerkingsmetodes nl. konvcnsionele bewerking (CT), tand bewerking (TT). minimum bewerking (MT) en geen bewerking (NT), twee gewasratasies nl. monokuhuur koring (WW) en koring/lupienelkoringiCanola (WLWC) en drie N-peie (60 kg N ha- ', 100 kg N ha- 1 , 140 kg N ha- I uitgevoer. Aile stikstof is in die vorm van kalksteen-ammoniumnitraat toegedien. Die reaksie van beide grondfaktore soos die minerale N inhoud en gewaskomponente 5005 biomassa produksie, opbrengs en kwaliteit teenoor bogenoemde faktore het '0 goeie korrelasie getoon met die heersende klimaatstoestande. Lae reenval jare (gebiede) sal volgens hierdie stlldie die grootste voordeel verkry met minder intensiewe grand bewerkingstelsels. terwyl 'n frekwensie van meer as een peulgewas per siklus van 4 jaar nodig sal wees om grondvrllgbaarhcidsvlakke betekenisvol te verhoog. Stelsels van rninder intensiewe grondbewerking is ook tot 'n grater mate deur gewaswisseling bevoordeel as konvensionele melOdes van grondbewerking. Hocwel minerale-N vlakke in grond deur verskillende N-peile be'lnvloed is, was die efTektiwiteit van toedienings laag en het verdeelde tocdienings groat voordele ingehou.
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Mbizana, Nandipha. "Identifying appropriate paths for establishing sustainable irrigated crop based farming business on smallholder irrigation schemes: a case of Ncora Irrigation Scheme." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1016205.
Full textAbstract:
The study examined the impact of small scale irrigation technology in crop production under Ncora areas of Cofimvaba. To achieve the objective of the study, data were collected from 212 farmers engaged in various crop enterprises under the Ncora. The farmers were randomly selected. Descriptive Statistics, DEA model, linear regression model and gross margin analysis were used to analyse the results obtained from the survey. The descriptive results showed that Ncora farmers are small-scale farmers cultivating small hectare of land and using simple farm tools, mainly using furrow irrigation. Furthermore, they produce more than one crop enterprises. The gross margin Analysis shows that Ncora cultivation is profitable. The most profitable crop was found to be maize than potatoes. Farm production function revealed that land, labour and purchased inputs had a positive relationship with the output of the enterprises. SPSS was used to run data for linear regression model (OLS). It was suggested that extension services and private organizations assist farmers especially the emerging ones via provision of training, processing and storage facilities. Furthermore, continuous monitoring of soil and water quality as well as ground water table was recommended, in order to ensure sustainability of Ncora irrigation in the area.
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Lewu, Muinat Nike. "Studies on the nutritional value of seven accessions of cocoyam growing in South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/d1001054.
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Cocoyam [Colocasia esculenta (L.) Schott] is widely cultivated as a staple food in the tropical and subtropical regions of the world. The crop, however, remains unpopular and not well known outside KwaZulu-Natal Province of South Africa where it is cultivated mainly for subsistence. The aims of the study were to collect local landraces (accessions) of the crop from where it is found growing within the country for various studies and also to document its nutritional values as well as the safety/toxicity of the crop. The study was carried out using various methods. These included a comparative assessment of the proximate, mineral and antinutrient compositions of cooked and uncooked tubers of a typical commercially available cocoyam and potato found in South African markets. These investigations were repeated for the tubers and leaves of available landraces (seven accessions) of C. esculenta found growing in the farmers’ fields in KwaZulu-Natal Province. Also, an in vivo toxicological study on cooked accessions of the local landraces was conducted to determine possible toxicity effects after consumption using albino rats as a model. The results revealed that commercially available cocoyam and potato tubers have very close nutritional components. Analysis of the proximate composition of seven accessions (UFCe1- UFCe7) of cooked and uncooked tubers of cocoyam indicated that UFCe7 was better in ash, crude protein, crude fibre and crude lipid contents but with higher moisture which could make it more vulnerable to microbial attack. No tubers of the seven accessions appeared to be ii outstandingly better than the others based on their mineral compositions. However, in terms of antinutritional factors, UFCe1, UFCe3 and UFCe7 had the least amounts of oxalate, tannins and phytate in their cooked states. It was discovered however, that the leaves of the accessions of this vegetable contain substantial amount of minerals, and therefore, can contribute significantly to the nutrient requirements of humans and could be recommended as a cheap source of nutrients in South Africa. None of the accessions was outstandingly better than the others in terms of their mineral contents and anti-nutritional factors. Moreover, the current study has shown that boiling the leaves of cocoyam prior to consumption is an effective way of reducing the antinutrient contents of the leaves of the plant thereby making it safe for consumption. The findings also revealed that cooking C. esculenta leaves may increase the levels of protein, fibre and lipid contents while cooking may also decrease the mineral, carbohydrate and caloric contents of the leaves of the accessions. The leafy vegetable may, therefore, be recommended as a cheap source of plant protein. Cooking improved the nutritive value as a result of the reduction in antinutrient levels, thereby improving the food quality in all the tuber and leaf samples used for this study. At the same time, cooked samples also suffered loss of some nutrients with respect to the proximate and mineral compositions. However, supplementation from other food sources that are rich in these nutrients is necessary when these crops are cooked for consumption. Any of the cocoyam accessions may be recommended for consumption for improved protein and mineral nutrients while tubers of accession UFCe7 have also shown good promise in terms of protein and fibre content availability. The results of the in vivo study, using the liver and kidney functional endpoints of weanling albino rats (Rattus norvegicus) maintained on different accessions of cooked cocoyam-based iii diets (UFCe1-UFCe7) for 28 days, revealed that all the accessions produced selective alterations on the hepatorenal indices of weanling rats. The highest alterations were produced by UFCe4 while the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. The UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in KwaZulu-Natal Province of South Africa.
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Chitsa, Gilbert. "Analysis of entrepreneurial behaviour of smallholder irrigation farmers: empirical evidence from Qamata Irrigation scheme." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1019769.
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Albeit much effort having been put to review the performance trend of smallholder irrigation farmers in South Africa. However, there seems to be a paucity of information regarding the level of entrepreneurship on these farmers. Most research works on smallholder irrigation farmers have mainly focused on livelihoods trajectory providing a review on how the welfare of the rural poor has been transformed after the introduction of irrigation schemes. With most research evidence indicating a high degree of underperformance on most smallholder irrigation schemes, this research attempted to investigate the level of entrepreneurship among the small holder irrigation farmers. In order to achieve the main research objective, a sample of 110 farmers drawn from Qamata irrigation scheme was interviewed and each farmer’s performance on the nine components of entrepreneurship was assessed. The aspects assessed to determine the farmer’s entrepreneurial behaviour were: planning ability, risk taking, achievement motivation, leadership ability, Cosmo politeness, decision making, and innovativeness and farming knowledge. Basing on previous studies which indicated entrepreneurial behaviour to be influenced by several factors the study also analysed the determinants of entrepreneurship among the irrigation farmers and a binary logistic regression model was used to establish the connection between various independent variables and the farmers’ entrepreneurial performance given as a total score of the nine components. Though the findings of the study revealed a prevalently low level of entrepreneurship among the smallholder irrigation farmers on Qamata irrigation scheme, a high proportion of the respondent farmers (65.5% and 60.5%) showed to have a high degree of achievement motivation and decision making ability, respectively. The observed trend thus reflected that smallholder farmers have a potential to become entrepreneurs and are willing to succeed. The binary model results revealed that the prevailing land tenure system will be a strong determinant of the farmer’s level of entrepreneurship. Equally, levels of training in farming, motive for farming and information seeking tendency also proved to have a significant influence on the degree of farmer entrepreneurship. Based on the results of this study recommendations have thus been drawn on the need for policies and practices aimed at promoting entrepreneurship and not dependency among farmers. Key focus areas identified include: the need to revise the current land ii tenure system on irrigation schemes, intensify on entrepreneurship training for both farmers and extension officers and regular on-farm training on new technologies.
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Mzuyanda, Christian. "Assessing the impact of primary agricultural co-operative membership on smallholder farm performance (crops) in Mnquma Local Municipality of the Eastern Cape Province." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1021285.
Full textBooks on the topic "Tuber crops south africa"
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Cooper, David. Commercial farming and wood resources in South Africa: Potential sources for poor communities. [Johannesburg, South Africa: Land and Agriculture Policy Centre, 1994.
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Mandota, Simba. Biofuel development, land use, and livelihoods in southern Africa: A synthesis of cases from Botswana, Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe. Harare]: Community Technology Development Trust, 2011.
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International Food Policy Research Institute, ed. Genetically modified crops in Africa: Economic and policy lessons from countries south of the Sahara. Washington, DC: International Food Policy Research Institute, 2013.
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Bruinsma, Domien. Review of food processing practices and opportunities in Africa: Cereals, root and tuber crops. Technical Centre for Agricultural and Rural Cooperation, 1996.
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Improvement of Sweet Potatoes in East Africa: With Some References of Other Tuber and Root Crops : Report. Agribookstore, 1989.
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Hadidi, Ahmed, Ricardo Flores, John Randles, and Joseph Semancik. Viroids. CSIRO Publishing, 2003. http://dx.doi.org/10.1071/9780643069855.
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This comprehensive volume presents indispensable and up-to-date information on viroids and viroid diseases. It provides a single source of information on the properties of viroids, the economic impact of viroid diseases, and methods for their detection and control. It examines the diseases associated with different plant species, the geographic distribution and epidemiology of viroids, diseases of possible viroid etiology, and the future applications of viroids.
Viroids examines the biology of viroids, molecular characteristics, localization and movement, replication, pathogenesis, viroids and gene silencing, classification, viroid-like satellite RNAs, detection of viroids using bioamplification hosts, biological indexing, polyacrylamide gel electrophoresis, molecular hybridisation and polymerase chain reaction. The book looks at the geographical distribution and epidemiology of viroids in North America, Australasia, China, Japan, Europe, the Middle East, Africa, South America, and at the global level. It covers the control of viroids including quarantine of imported germplasm, availability of viroid-tested propagation materials, thermotherapy, tissue culture, and other conventional strategies as well as biotechnological control approaches. Special topics such as ribozyme reaction of viroids and economic advantages of viroid infection are also included. Other chapters summarise the current state of knowledge concerning viroid diseases of the crop in question and aspects of the natural history of viroids in horticulture. Among the crops covered are potato, tomato, tobacco, cucumber, pome fruits, stone fruits, avocado, citrus, grapevines, hop, chrysanthemum, coleus, columnea, and coconut palm.
The four eminent editors of this watershed volume have assembled an international group of more than 70 scientists who have substantial experience with viroids and viroid diseases. They have produced a cohesive and comprehensive work that can be used by students, researchers, extension agents, and regulators. It may also be of a great value to science managers, policy makers, and industries in formulating policies and products to obtain viroid-free plants and control viroid diseases. The information on plant quarantine and certification programs will help anyone concerned with the safe movement of plant material across international boundaries or within a single country.
Book chapters on the topic "Tuber crops south africa"
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Morris, E. Jane, and Jennifer A. Thomson. "Genetically Modified Crops Commercialized in South Africa." In Biotechnology in Africa, 53–65. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04001-1_4.
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Osei, Michael Kwabena, Eric Cornelius, Elvis Asare-Bediako, Allen Oppong, and Marian Dorcas Quain. "Status of Begomoviruses in Ghana: The Case of Vegetables and Root and Tuber Crops." In Begomoviruses: Occurrence and Management in Asia and Africa, 297–314. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-5984-1_18.
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van Biljon, Elizabeth R. "Nematode Pests of Tobacco and Fibre Crops." In Nematology in South Africa: A View from the 21st Century, 285–310. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44210-5_12.
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Fourie, Hendrika, Alexander H. Mc Donald, Sonia Steenkamp, and Dirk De Waele. "Nematode Pests of Leguminous and Oilseed Crops." In Nematology in South Africa: A View from the 21st Century, 201–30. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44210-5_9.
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Scoones, Ian. "Mobilizing Against GM Crops in India, South Africa and Brazil." In Transnational Agrarian Movements Confronting Globalization, 147–75. Oxford, UK: Wiley-Blackwell, 2009. http://dx.doi.org/10.1002/9781444307191.ch6.
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Jones, Robin K., Sheila G. Storey, Rinus Knoetze, and Hendrika Fourie. "Nematode Pests of Potato and Other Vegetable Crops." In Nematology in South Africa: A View from the 21st Century, 231–60. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44210-5_10.
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Daneel, Mieke S. "Nematode Pests of Minor Tropical and Subtropical Crops." In Nematology in South Africa: A View from the 21st Century, 373–93. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44210-5_17.
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Mc Donald, Alexander H., Dirk De Waele, and Hendrika Fourie. "Nematode Pests of Maize and Other Cereal Crops." In Nematology in South Africa: A View from the 21st Century, 183–99. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44210-5_8.
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Majumdar, Kaushik, Robert M. Norton, T. Scott Murrell, Fernando García, Shamie Zingore, Luís Ignácio Prochnow, Mirasol Pampolino, et al. "Assessing Potassium Mass Balances in Different Countries and Scales." In Improving Potassium Recommendations for Agricultural Crops, 283–340. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-59197-7_11.
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AbstractEstimating nutrient mass balances using information on nutrient additions and removals generates useful, practical information on the nutrient status of a soil or area. A negative input–output balance of nutrients in the soil results when the crop nutrient removal and nutrient losses to other sinks become higher than the nutrient inputs into the system. Potassium (K) input–output balance varies among regions that have different climates, soil types, cropping systems, and cropping intensity. This chapter illustrates the farm-gate K balances in major production areas of the world and their impacts on native K fertility and crop yields. On-farm and on-station research examples show significant negative K balances in South Asia and Sub-Saharan Africa, while China, the USA, Brazil, and countries of the Latin America Southern Cone highlighted continued requirement of location-specific K application to maintain crop yields and soil K fertility status at optimum levels.
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Muimba-Kankolongo, Ambayeba. "Root and Tuber Crops." In Food Crop Production by Smallholder Farmers in Southern Africa, 123–72. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-814383-4.00009-8.
Full textConference papers on the topic "Tuber crops south africa"
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Roux, A. S. "Promoting the effective use of water in the irrigation of permanent crops in the Western Cape Province of South Africa." In SUSTAINABLE IRRIGATION 2006. Southampton, UK: WIT Press, 2006. http://dx.doi.org/10.2495/si060321.
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Agyemang, Malena, and Nathan G. Johnson. "Development of Biomass Energy Technologies and Business Models for Southern Africa." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-48033.
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This study evaluates options for biomass pellet formulations and business models to create a sustainable energy solution for cooking energy in Southern Africa. Various agricultural wastes and agro-processing wastes are investigated to meet industry standards on biomass pellet quality. These fuels are obtained from farms and facilities across a geographic area that affects the end-cost of the pellet through transportation costs and the cost of the biomass. The technical performance of the pellet and cost of the pellet are first contrasted and then optimized in unison to develop sustainable energy options that can provide year-round clean energy for household cooking and heating needs. A market was analyzed using wheat, sugarcane and maize crops as components for the biomass pellet fuel source in the Zululand district of South Africa. Using a target moisture content (MCtarget) of 8–10%, a target lower heating value (LHVtarget) greater than 16.0 MJ/kg and a target percent ash (Ashtarget) less than 3%, pellet metrics were optimized. The cost of the crops for the pellets was dependent upon the amount of each biomass used to make up the composition of the pellet. The production demand was then analyzed based on the most current consumer cooking fuel demand within South Africa. The production model was evaluated for three factory sizes; small (1hr/ton), medium (3hr/ton), and large (5hr/ton). Primary shipping cost is based on factory location and has a major impact on the cost of the pellet for the consumer as well as the availability of the supply. Factory location was analyzed by varying the biomass crop distance to the factory. Several business models are evaluated within this study to show which representation results in a high quality pellet of low cost to consumer. The study suggests the pellet be composed of 44.62% sugarcane, 47.49% maize, and 0.82% wheat resulting in a LHV of 16.00 MJ/kg, a MC of 8 (w/w%), and an ash content of 3 (w/w%). The optimal cost of the biomass fuel pellet for the consumer ranged from 172.77US$/ton to 185.03 US$/ton.
Reports on the topic "Tuber crops south africa"
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Gause, Marnus. Socioeconomic and farm-level effects of genetically modified crops: The case of Bt crops in South Africa. International Food Policy Research Institute, 2009. http://dx.doi.org/10.35648/20.500.12413/11781/ii089.
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Falck-Zepeda, José Benjamin, Guillaume Gruère, and Idah Sithole-Niang. Genetically modified crops in Africa: Economic and policy lessons from countries south of the Sahara. Washington, DC: International Food Policy Research Institute, 2013. http://dx.doi.org/10.2499/9780896297951.
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