Improving cultivation of groundnuts

Groundnut (also known as peanut) (Arachis hypogaea L.), a native of South America, has often been referred to as an unpredictable legume in the past (Gregory and Gregory, 1979; Hammons, 1994). The genus Arachis contains 81 described species, categorized into nine taxonomic sections, and includes both diploids and tetraploids belonging to either annual or perennial type. The classification is based on morphology, geographical distribution and cross-compatibility among the species (Valls and Simpson, 2005). The only cultivated groundnut, Arachis hypogaea L., is further divided into two sub-species ‘hypogaea’ and ‘fastigata’ based on the branching pattern and the distribution of vegetative and reproductive axes. Although it has been known to humankind for many centuries, its commercial cultivation started only in early 1900, when it began receiving research attention..

Proceedings of the 4th Regional Groundnut Workshop for Southern Africa, Arusha, Tanzania, 19-23 Mar 1990

Twenty-three out of 32 national program scientists actively engaged in groundnut improvement in the Southern African Development Coordination Conference (SADCC) region participated in the Regional Workshop; Angola and Zimbabwe were the only countries of the region not represented in person. However, a paper by a groundnut scientist in Zimbabwe was accepted as presented in his absence. Also participating were groundnut scientists from Kenya, Maur i t ius, Uganda, ICRISAT Center (India), ICRISAT Saheiian Center (Niger ), SADCC/ ICRISAT Groundnut Project (Malawi), and ICRISAT's Eastern Africa Regional Cereals and Legumes program (Kenya). Papers reviewed groundnut research on breeding, entomology, agronomy, leaf spot diseases, and cropping systems. The recommendations of the Workshop's plenary session provide valuable guidelines for regional project activities

Resistance to Thrips in Peanut and Implications for Management of Thrips and Thrips-Transmitted Orthotospoviruses in Peanut

Thrips are major pests of peanut (Arachis hypogaea L.) worldwide, and they serve as vectors of devastating orthotospoviruses such as Tomato spotted wilt virus (TSWV) and Groundnut bud necrosis virus (GBNV). A tremendous effort has been devoted to developing peanut cultivars with resistance to orthotospoviruses. Consequently, cultivars with moderate field resistance to viruses exist, but not much is known about host resistance to thrips. Integrating host plant resistance to thrips in peanut could suppress thrips feeding damage and reduce virus transmission, will decrease insecticide usage, and enhance sustainability in the production system. This review focuses on details of thrips resistance in peanut and identifies future directions for incorporating thrips resistance in peanut cultivars. Research on thrips–host interactions in peanut is predominantly limited to field evaluations of feeding damage, though, laboratory studies have revealed that peanut cultivars could differentially affect thrips feeding and thrips biology. Many runner type cultivars, field resistant to TSWV, representing diverse pedigrees evaluated against thrips in the greenhouse revealed that thrips preferred some cultivars over others, suggesting that antixenosis “non-preference” could contribute to thrips resistance in peanut. In other crops, morphological traits such as leaf architecture and waxiness and spectral reflectance have been associated with thrips non-preference. It is not clear if foliar morphological traits in peanut are associated with reduced preference or non-preference of thrips and need to be evaluated. Besides thrips non-preference, thrips larval survival to adulthood and median developmental time were negatively affected in some peanut cultivars and in a diploid peanut species Arachis diogoi (Hoehne) and its hybrids with a Virginia type cultivar, indicating that antibiosis (negative effects on biology) could also be a factor influencing thrips resistance in peanut. Available field resistance to orthotospoviruses in peanut is not complete, and cultivars can suffer substantial yield loss under high thrips and virus pressure. Integrating thrips resistance with available virus resistance would be ideal to limit losses. A discussion of modern technologies such as transgenic resistance, marker assisted selection and RNA interference, and future directions that could be undertaken to integrate resistance to thrips and to orthotospoviruses in peanut cultivars is included in this article

An Intercropping Bibliography

This issue was undated. The date given is an estimate.126 pages, 1 article*An Intercropping Bibliography* (Federer, Walter T.) 126 page

Evaluation of the performance of groundnut genotypes and their resistance to groundnut rosette virus.

Master of Science in Plant Breeding. University of KwaZulu-Natal, Pietermaritzburg, 2017.The groundnut or peanut is one of the important legume crops of tropical and semi-arid tropical countries, where it provides a major source of edible oil and vegetable protein. The crop is mainly grown by smallholder farmers with little inputs, resulting in low yields of 700 kg/ha compared to Asia and south America which records 3500 kg/ha and 2500 kg/ha respectively. The low yields are due to a number of abiotic and biotic factors with diseases being a major constraint. Amongst the diseases, groundnut rosette disease can cause up to 100% yield loss when infection occurs. The objectives of this study were to; (i) evaluate the ICRISAT elite lines for rosette resistance using artificial inoculation, (ii) determine the effect of genotype by environment interaction of landraces and elite lines and select for stability and high yield, and (iii) determine the genotype by trait interaction for the landraces so as to select potential genotypes for use as parents in the breeding programme. To achieve objective one, glasshouse and field inoculation experiments were conducted using the infector row technique. In the glasshouse, the results revealed that ICGV SM 08503 and ICGV SM 01514 were resistant and showed 0% disease incidence while ICGV SM 01711, ICGV SM 09547, ICGV SM 09537, ICGV SM 08501 and ICGV SM 09545 showed moderate resistance with scores ranging from 1.1 to 1.7. ICGV SM 02724, ICGV SM 10005 and ICGV SM 08560 showed high susceptibility with scores as high as 4.6. However, the susceptible genotypes ICGM SM 10005, ICGV SM 02724 and ICGV SM 08560 showed low incidences of the disease in the field evaluation. At 60 days after sowing (DAS), the incidence ranged from 9.9% to 16.5% while at 80 DAS, it ranged from 18.6% to 23.8%. The highest score for disease incidence at 100 DAS was 27.3% for genotype ICGV SM 08560. The rest of the genotypes had 0% incidence. The yield per hectare ranged from as low as 0.32 ton/ha to as high as 1.03 ton/ha. ICGV SM 10005 recorded the lowest yield while ICGV SM 01711 was the highest yielding genotype with 1.03 ton/ha. For the genotype x environment study, a total of 11 groundnut genotypes from ICRISAT comprising of nine elite lines and two released cultivars as controls were evaluated over ten environments spread across the three agro-ecological zones of Zambia in the 2016/17 season. Additive main effect and multiplicative interaction (AMMI) and genotype and genotype by environment interaction (GGE) biplot models showed that ICGV SM 01711 and ICGV SM 02724 were high yielding recording 2.08 t/ha and 1.99 t/ha, respectively, compared to the average mean of 1.67 t/ha across all environments and showed relative stability. ICGV SM 10005 and ICGV SM 08560, which are Spanish genotypes, yielded 1.67 t/ha and 1.60 t/ha, respectively, compared to Luena (control) which yielded 1.23 ton/ha. ICGV SM 10005 had better relative stability over ICGV SM 08560 and Luena. Genotype x trait analysis, correlation and path coefficient analysis on a total of eight landraces, two pre-released cultivars and five released cultivars showed a strong and highly significant correlation for grain yield with number of pods per plant, yield per plant, shelling percentage and 100-seed weight with r values of 0.86, 0.90, 0.94 and 0.23, respectively, at P<0.001 but 100-seed weight’s correlation was not significant. The path coefficient analysis revealed that yield per plant, shelling percentage, number of pods per plant, 100-seed weight and days to maturity had a positive direct effect on grain yield while days to flowering had negative direct effect on grain yield. Genotype by trait (GT) biplot captured 83.00% of the variation due to genotype by trait interactions. Two land races, Kasele and Chalimbana performed relatively well in relation to MGV 4 and it was recommended that these could be hybridized with genotypes that have complementary features so that beneficial alleles are combined for improvement of the crop, while genotypes ICGV SM 01514, ICGV SM 01711 and Chishango can be used as sources of resistance genes

Compendium of peanut diseases

Compendium of Peanut Diseases, Second Edition is a guide to the identification, diagnosis, and control of peanut diseases and disorders. Bringing together color photographs and authoritative information in a single volume, this convenient compendium is a valuable resource for peanut growers and crop consultants around the world. This compendium has become a standard guidebook for the peanut industry. The contributors are an international group that includes 50 peanut experts from the United States, India, The Peoples Republic of China, Malawi, Australia, Israel, and South Africa. They offer advice on diseases and disorders found in each of the world's major peanut-growing regions. Detailed descriptions of 55 peanut diseases are the core of the book. Covering diseases caused by fungi, bacteria, nematodes, and viruses, these descriptions present detailed information on symptoms, causal organisms, disease cycle, control, host range, transmission, detection, and epidemiology. In addition to diseases, the compendium also describes peanut disorders caused by environmental stress, insects and arthropods, and parasitic flowering plants. Other sections of the compendium cover beneficial organisms, organisms with an undetermined relationship to peanuts, disease management strategies, genetic modification, and a listing of disease and insect resistant cultivars currently available for use by growers and breeder

Investigations into the incidence and ecology of bilobata subsecivella (zeller) (lepidoptera: gelechidae) : a new pest of groundnut in South Africa.

Doctor of Philosophy in Entomology. University of KwaZulu-Natal, Pietermaritzburg 2015.The leaf-mining moth, Bilobata subsecivella (Zeller) (Lepidoptera: Gelechiidae), thought to be an invasion from Indo-Asia (where it is known as Aproaerema modicella (Deventer); but hereafter referred to as B. subsecivella) has become a major pest of groundnut (Arachis hypogaea L.) and soya bean (Glycine maxi (L.) Merr.) in South Africa and Africa as a whole. Following the sudden outbreaks of B. subsecivella as a new pest of groundnut in a number of African countries, the continent has been confronted with the problem of having no information on the biology and ecology of the pest that can be used for its management/control. In this context, the main aim of the research for this thesis was to study the biology and ecology of B. subsecivella in South Africa with the main objective of obtaining information that will assist in its management as a novel pest of groundnut. To achieve this objective, several studies were carried out. First, a detection survey of B. subsecivella infestation was conducted on groundnut, soya bean and lucerne (Medicago sativa L.), the common host crops for B. subsecivella in India, at six widely separated sites in South Africa during the 2009/2010 growing season. The sites included the Agricultural Research Council research stations at Potchefstroom and Brits as well as the farms surrounding the Brits research farm in the North West province, Vaalharts Research Station in the Northern Cape province, the Department of Agriculture Lowveld Agricultural Research Station near Nelspruit in Mpumalanga province, and Bhekabantu and Manguzi in the northern part of the KwaZulu-Natal province. The study had three objectives. The first was to build a complete host crop/plant list and record damage symptoms caused by B. subsecivella in South Africa. The second was to identify the pest to species level. The third was to determine its inter- and intra-population genetic diversity by analysing in, both cases, the mitochondrial DNA (mtDNA) COI gene of specimens collected from these sites. Sixty specimens comprising 24 larvae, 24 pupae and 12 moths were collected from the six survey sites, and their mtDNA COI were sequenced and compared with those from the Barcode of Life Data System (BOLD) gene bank. Infestation by B. subsecivella was observed on groundnut and soya bean, but not on lucerne. The mtDNA COI from all specimens of the pest, irrespective of whether they were from groundnut or soya bean, matched 100% with the sequences in BOLD belonging to a B. subsecivella population occurring in Australia (referred to as Aproaerema simplexella (Walker)) and known as the soya bean moth in that country). There was very little genetic diversity between and within the populations from the six sites, which suggested that the populations were maternally of the same origin. Further molecular and phylogenetic studies were also completed to determine the evolutionary relationships between B. subsecivella populations collected from Australia, Africa and India. These studies involved sequencing and analysing five gene regions of mitochondrial and nuclear DNA, including COI, cytochrome oxidase II (COII), cytochrome b (cytb), 28 ribosomal DNA (28S rDNA), and intergenic spacer elongation factor-1 alpha (EF-1 ALPHA). The mtDNA COI analysis also included B. subsecivella (but called A. simplexella) sequences downloaded from the National Center for Biotechnology Information (NCBI) GeneBank collected from different areas in Australia. In four phylogenetic trees (COI, COII, cytb and EF-1 ALPHA), sequences of B. subsecivella personally sampled from Australia were grouped separately from the others, whereas sequences of B. subsecivella from South Africa, India and Mozambique were clustered in one group in most cases. Furthermore, in the mtDNA COI phylogenetic tree, one Australian sequence of B. subsecivella that was downloaded from the NCBI GeneBank was grouped with other sequences from South Africa, India and Mozambique. Moreover, one sequence of B. subsecivella personally sampled from Australia was grouped with the other two sequences of B. subsecivella from Australia that were downloaded from the NCBI GeneBank. Based on these results, it could be hypothesized that there is genetic diversity within B. subsecivella populations in Australia. The mtDNA COI gene analysis in the current study revealed that there are B. subsecivella populations in Australia that are similar to the B. subsecivella populations in South Africa, Mozambique and India. Phylogenetic analysis of the 28S gene region revealed a lack of genetic diversity between sequences of B. subsecivella from India, South Africa, Mozambique and Australia. Genetic pairwise distances between the experimental sequences ranged from 0.97 to 3.60% (COI), 0.19% to 2.32% (COII), 0.25 to 9.77% (cytb) and 0.48 to 6.99% (EF-1 ALPHA). Field experiments were then conducted at Vaalharts, Brits, Nelspruit, Manguzi and Bhekabantu during the 2010/2011 and 2011/2012 growing seasons. These experiments pursued three objectives. The first one was to determine B. subsecivella infestation levels on groundnut, soya bean, lucerne, pigeon pea (Cajanus cajan L.) and lablab bean (Lablab purpureus L.) under field conditions. The second was to develop a host plant list for B. subsecivella and the third was to determine the effect of cypermethrin application on damage by B. subsecivella to groundnut and soya bean plants. In the 2010/2011 season, larval infestation was monitored on groundnut crops planted in November 2010 and January 2011. In the 2011/2012 season, larval infestation was monitored on groundnut, soya bean, lucerne, pigeon pea and lablab bean planted in November 2011 and January 2012. Wild host plants were inspected for damage symptoms and the presence of larvae. An experiment which examined the effect of cypermethrin application on B. subsecivella damage to groundnut and soya bean plants was completed in the 2011/2012 season at Vaalharts and Nelspruit. A survey for wild plant hosts of B. subsecivella was conducted in the proximity of the field experiments during the 2011/2012 growing season, as well as in winter. Amongst the host crops tested, soya bean was highly infested by B. subsecivella followed by groundnut, at all sites. The pest was also observed on pigeon pea at all sites, but the infestation was very low, while lucerne had very low larval infestation. No infestation was observed on lablab bean across these sites. Groundnut and soya bean crops planted in January were severely infested by B. subsecivella, compared to the crops planted in November; however, B. subsecivella infestation on crops was observed 5-6 weeks after crop emergence. Sprays of cypermethrin on groundnut and soya bean reduced larval infestation in both crops to very low levels. Wild plant hosts identified were from five families which included three species in the Leguminosae, two species in the Convolvulaceae, two species in the Malvaceae and one species each in the Lamiaceae and Asteraceae. Seasonal monitoring of the flight activity of B. subsecivella moths was completed at Manguzi, Bhekabantu, Nelspruit, Brits and Vaalharts over a two-year period (from November 2010 to December 2012). The objective of this study was to monitor the flight activity of B. subsecivella in order to understand its dispersal and off-season survival tactics and to predict its initial occurrence. Pheromone traps were used to monitor the moths’ flight activity. Information collected included climatic data (rainfall, temperature and humidity) that were obtained from ARC weather stations placed at four planting sites. Pearson’s test for correlation was performed to assess the relationship between B. subsecivella moth catches and environmental factors (rainfall, temperature and humidity). Results from this study showed variation in B. subsecivella populations throughout the monitoring period. The highest peak in B. subsecivella catches was between January and April/May for both seasons. Though low in numbers, B. subsecivella moths were caught in winter at Manguzi, Nelspruit, Vaalharts and Bhekabantu. No B. subsecivella moths were trapped during the winter months at Brits. Pearson’s test for correlation indicated that there was a significant negative association between temperature and B. subsecivella catches in pheromone traps at Nelspruit, whereas at Vaalharts there was a significant positive association between humidity and B. subsecivella catches. There was no correlation between environmental factors and B. subsecivella catches at Manguzi and Brits. Furthermore, it was found that B. subsecivella in Australia (moths collected for DNA analysis in the current study) responded to the species-specific lure that was developed from the sex pheromone of B. subsecivella, referred to as A. modicella in India. Overall, the study revealed important ecological and genetic information on B. subsecivella populations occurring in southern Africa. More importantly, this study established the genetic connection between B. subsecivella populations from Australia, India and Africa. Hence, the species conforming to these populations were tentatively synonymized as B. subsecivella in this thesis