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Genetic diversity is crucial for crop improvement in any breeding program. Cowpea is an important indigenous grain vegetable legume crop. The crop has a significant potential to improve food and nutritional security in sub-Saharan Africa (SSA), and family income for resource poor famers. Cowpea is a source of proteins, vitamins (folate, thiamine and vitamin C), minerals (Fe, Zn, Mn and Ca) and amino acids such as lysine and tryptophan, hence, has a high potential for combating nutrient deficiencies. The SSA countries, including South Africa, have been experiencing many dry seasons, which have negatively affected agricultural production and productivity. Cowpea has a long taproot with the ability to grow in arid and semi-arid regions; however, lasting exposure to severe droughts will result in significant yield and grain quality reduction. There has been limited progress in drought tolerance research in cowpea due to the complexity of this trait, as it involves numerous genes, which in turn are affected by environmental conditions. It is therefore important to review research done on the nutritional, phenotypic and genotypic diversity of cowpea and the importance of diversity when breeding for complex quantitative traits such as drought tolerance and yield. The review will also outline the important omics tools used for drought tolerance breeding, cultivar development and as reference for future cowpea breeding. Cowpea is a highly nutrient-dense, underutilised orphan legume crop with high potential to address malnutrition and food security in the world. Cowpea crop can withstand drought and high-temperature conditions, however, lasting exposure to severe droughts will result in significant yield reduction and poor grain quality. Thus, understanding the variation present in the available cowpea accessions will assist in breeding superior cowpea varieties that can withstand the ever-changing climate. [ABSTRACT FROM AUTHOR]

• Bambara groundnut productivity in South Africa is low (0.62 t/ha) compared to the attainable yield of the crop reaching up to 3 t/ha. • The low productivity is attributable to a lack of improved and high yielding cultivars that are locally bred and adapted in the country. • This paper presents baseline information on Bambara groundnut genetic profile of South African collections for effective breeding and conservation. • The magnitude of the genetic diversity and population structure of Bambara groundnut collections of South Africa using high throughput single nucleotide polymorphisms (SNP) markers are highlighted to guide current and future Bambara groundnut research and development by selection genetically unique genotypes for breeding. Bambara groundnut (Vigna subterranea [L.] Verdc) is a highly nutritious grain legume with a significant potential to develop various commercial food and feed products. It is a resilient crop able to grow under harsh climates and poor soil conditions. Bambara groundnut productivity in South Africa is low (0.62 t/ha) compared to the attainable yield of the crop reaching up to 3 t/ha. The low productivity is attributable to a lack of improved and high yielding cultivars that are locally bred and adapted in the country. Genetically diverse and locally adapted Bambara groundnut landrace varieties and exotic collections are present in South Africa for strategic breeding to improve yield and yield-related traits and nutritional quality. The objective of this study was to determine the magnitude of the genetic diversity and population structure of Bambara groundnut collections of South Africa using high throughput single nucleotide polymorphisms (SNP) markers. Ninety-three genotypes were assessed using genotyping with 2286 SNP markers and some unique complementary morpho-agronomic traits of the crop. The mean genetic diversity value was 0.32, revealing moderate genetic differences among the assessed genotypes. Cluster and structure analyses grouped the test genotypes into two distinct categories. Further, the analysis of molecular variance partitioned the total genetic variation into among genotypes (90%), within genotypes (8%) and among populations (2%). The results revealed two heterotic groups for hybridization and selection programs. The following unique genotypes were selected: ARC Bamb 37 (with spreading growth type), ARC Bamb 49 (bunch type), ARC Bamb 61 (semi-bunch) and ARC Bamb 83 (spreading) using the SNP markers and desirable agronomic traits. The study provided new insight on Bambara groundnut genetic profiles of South African collections which will assist in conservation strategy and management of the crop for effective breeding. [ABSTRACT FROM AUTHOR]

Correlations and path coefficient analysis provide knowledge on trait interrelationships and potential for simultaneous, direct, or indirect selection in plant breeding. The objective of this study was to determine the genetic and phenotypic correlations as well as the path coefficient analysis among grain yield components and nutritional quality traits in cowpea genotypes. Data for grain yield components and mineral elements were collected from 70 cowpea genotypes planted at two environments in 2017/18 and 2018/19 seasons in South Africa. Grain yield had significant (P <0.05) positive phenotypic correlations with number of seeds per pod (SPP), indicating that selection of cowpea genotypes based on SPP could be effective in maximizing grain yield. The heat map showed that grain yield was strongly associated with number of branches (NB), SPP and number of pods per plant. Among the yield components, only SPP showed significant (P <0.05) positive phenotypic correlations with Zn, Mn, and Mg. Grain yield showed no genetic correlations with yield components and nutritional quality traits. Significant (P <0.05) positive genetic correlations were observed between yield components and most of the nutritional quality traits, indicating inherent association among the traits. Path coefficient analysis identified SPP and NB as major contributors to grain yield. The PCA identified cowpea genotypes such as ARC030, ARC011, ARC016, ARC024, NGOII, ARC032, IT90K59, and ARC047 with high grain yield and good nutritional quality traits that can be used further as potential parents for crop improvement through biofortification. The clustered heat map distingished five groups of cowpea genotypes and three of those were associated with good grain yield and nutritional quality traits which could make cowpea a good choice to combat food security and malnutrition in the world. [Display omitted] • Genetic and phenotypic correlations as well as the path coefficient analysis among grain yield components and nutritional quality traits in cowpea genotypes were determined. • Correlations and path coefficient analysis provide knowledge on trait interrelationships and potential for simultaneous, direct, or indirect selection in plant breeding. • Grain yield had significant positive phenotypic correlations with number of seeds per pod, indicating that selection of cowpea genotypes based on SPP could be effective in maximizing grain yield. • Seed pods per plant showed positive phenotypic correlations with Zn, Mn, and Mg. • Path coefficient analysis identified seed per pod and branches per plant as major contributors to grain yield in cowpea. [ABSTRACT FROM AUTHOR]

• Cowpea is a highly valued fruit and leafy vegetable crop contributing to food, nutrition, and health security. • Low cowpea production and productivity in sub-Saharan Africa and globally are due to a lack of improved cultivars with multiple disease, and insect pest resistance and drought tolerant; moreover, there is a lack of seed system research in cowpea. • The extensive phenotypic and genotypic variation found in cowpea genetic resources is useful for the development of cultivars with enhanced grain yield, leafy yield and nutritional values as well as drought tolerant. Despite the contribution of cowpeas to food security and the crop's numerous nutritional and health attributes, consumers in South Africa have labelled cowpeas, among other leguminous crops as a "poor people's food" ; this contributed to the gradual decline in the cultivation and use of the crop. This, in turn, resulted in the observed high reliance on limited number of plant based protein crops and excessive consumption of livestock products. In this paper, three aspects are interrogated, i.e., genetic resource management, production constraints as well as the trade performance and consumption of cowpeas in South Africa. A clear understanding of these aspects renders an informed decision upon which recommendations for the necessary practical interventions that are needed to be put in place to spur the development of target products and cowpea's value chain. The assessment of genetic resource management and seed production constraints of cowpeas was based on a review of relevant literature, while descriptive analysis of secondary data spanning a period of 10 years (2010-2019) obtained from Trade Map and FAOSTAT databases was used to interrogate the trade performance and consumption of cowpeas. Findings reveal that seed production constraints are largely anchored on the limited attention government and policy making institutions have accorded to the seed system of orphaned crops, thereby compromising their potential by failing to supply affordable good quality seeds to smallholder and commercial farmers. However, South Africa has one of the largest and most diverse collections of cowpea germplasm housed at the Agricultural Research Council. With regard to trade performance and consumption, results show that South Africa is a net exporter of cowpeas, with a 10 years' period annual average worth R2.9 million. Given that South Africa does not re-export cowpeas, yet on average 4848 tonnes are produced annually, it is a clear indication that the country produces lightly more than what is consumed domestically – on average 4634 tonnes per annum. Therefore, recommendation is made to bolster cowpea production and productivity through mainstreaming the legume seed system towards boosting local and export markets as well as strongly enhancing local consumption by creating awareness of the nutritional and health benefits of cowpeas. Furthermore, there is a need to increase awareness about the nutritional and health benefits of cowpeas and other leguminous crops, among other socio-economic benefits. This is important in spurring cowpeas consumption domestically, while countering the over reliance on animal products as protein sources and the associated risks such as such as high greenhouse gas emissions and obesity for people. [ABSTRACT FROM AUTHOR]

The identification of high-yielding and stable genotypes for cultivation across differential production regions is among the key breeding objectives in cowpea improvement programs. This study was aimed to determine genotype-by-environment interaction (GEI) for grain yield to select high-yielding and stable cowpea genotypes for production in South Africa and identical agro-ecologies, and for cultivar development. Fifty cowpea genotypes were tested for grain yield across seven environments of South Africa using a 10 × 5 alpha lattice design replicated three times, during the 2019/2020 and 2020/2021 planting seasons. Grain yield data were subjected to analysis of variance (ANOVA), additive main effects and multiplicative interaction (AMMI) and the genotype-by-environment interaction (GGE) biplot analyses. ANOVA and AMMI showed significant genotype, environment and GEI effects. High grain yield was recorded for genotypes G35 (0.47 t ha−1), G1 (0.45 t ha−1) and G47 (0.43 t ha−1) across test environments. AMMI stability values (ASV); identified Acc-Cowp44 as the most stable genotype across all sites, recording the lowest ASV of 0.03. The comparison view of GGE biplot revealed Acc-Cowp29, Acc-Cowp38 and Acc-Cowp5 as ideal genotypes, possessing high grain yield of 0.19, 0.47 and 0.36 t ha−1, respectively. The identified genotypes are recommended for production and inclusion in subsequent breeding activities. [ABSTRACT FROM AUTHOR]

Cowpea is an important food and nutritional security grain legume crop in the semi-arid regions of sub-Saharan Africa. Its production is limited by biotic factors including pre-harvest insect pests such as aphids. Aphids cause yield reductions, promotes the growth of sooty moulds, honeydew and as a result reduce photosynthetic processes and rates. Various methods have been deployed to try to control the damage of aphids in cowpea plants. The methods include the use of chemical insecticides, cultural, mechanical, biological controls and integrated pest management. However, these methods have not been very effective as smallholder farmers growing cowpea in marginal areas cannot afford them. Hence, host plant resistance/genetic control is the best and effective method for controlling aphids in cowpea plantations. Breeding for aphid resistance is one of the effective methods that can sustain the production and productivity of the cowpea for longer periods. Furthermore, assessing the presence of genetic diversity can also help in sourcing genes of novelty for addressing this important issue to increase the production and productivity of the crop. Recently, scientists have used various strategies to try to solve the challenge of aphid damage on cowpea. The objective of this review was to document the research progresses on aphid resistance breeding of cowpea to facilitate the breeding and conservation of cowpea germplasm. The review serves as a baseline information to guide future cowpea breeding for resistance to aphids. [ABSTRACT FROM AUTHOR]

Cowpea (Vigna unguiculate L.) is an important legume crop due to its nutritional value and it has the potential to contribute to the alleviation of malnutrition in the world. The study objectives were to determine the variability among 70 cowpea genotypes for the concentration of mineral elements and phytochemical contents, identify superior genotypes for mineral elements and phytochemical contents, and to determine the correlation among traits. Data were collected from 70 cowpea genotypes planted in two different locations during the 2017/18 and 2018/19 cropping seasons in South Africa. Grain samples were analysed for selected minerals such as Fe, Zn, Ca, Cu, K, Mg, Mn, Na, P, and phytochemical contents including total phenolic and flavonoid. Genotype, locations, seasons, and their interaction effects were highly significant (p < 0.001) for all traits. Best linear unbiased predictors identified superior genotypes for all traits in both locations. There were significant (p < 0.05) correlations among most of the traits evaluated. The high negative association of total phenolics with most of the minerals indicated that selecting for total phenolics may unintentionally reduce the content of minerals. These results will contribute to the development of improved cowpea cultivars for nutritional value towards alleviating malnutrition in the world. [ABSTRACT FROM AUTHOR]

The identification of stable and adaptable high yielding cowpeas (Vigna unguiculata (L.) Walp.) and highly discriminative environments will be useful for elite cultivar development in South Africa. Two statistical models, the Additive main effects multiplicative interaction (AMMI) and the genotype, genotype by environment biplot analysis have been used extensively to identify superior genotypes and ideal testing environments. Hence, the objective of this study was to identify elite cowpea lines and testing environments using the two models to inform future cultivar development strategies. Fifteen cowpea genotypes were evaluated for yield performance and stability across 3 different locations during 2016 and 2017 growing seasons in South Africa. Genotype main effects were significant for grain yield, while genotype × environment interaction effect was insignificant for grain yield. However, genotypic perfomance for grain yield was significantly affected by seasonal variability. The AMMI analysis of variance showed that genotypes (G), environments (E) and their interaction were significant for grain yield. The G and GE effects accounted for about 10% of the total variation in grain yield, while the environment accounted for 66%. The high yielding genotypes, Vigna Onb, TVU-5431 and Kisumu mix, were adapted to Mafikeng and Potchefstroom sites. Kisumu mix, followed by Vigna Onb, were the most stable genotypes, while Veg cowpea 1, Veg cowpea dacama cream and Veg cowpea 2 were the least stable genotypes across the three sites and seasons. The analysis also showed that Environment 4 (Potchefstroom) was the most ideal site for cowpea production among the test sites. [ABSTRACT FROM AUTHOR]

Cowpea is a drought tolerant food legume but yields are generally low in South Africa due to non-availability of improved varieties. The current study was undertaken to evaluate agronomic performance of cowpea germplasm and select the candidate accessions for breeding population and cultivation by small-scale farmers in South Africa. A randomized complete block design with three replications was used for the experiment. Data were collected on the agronomic traits including days to 50% maturity, days to 95% maturity, hundred seed weight, leaf area index, number of branches, number of internodes, number of seeds per plant, plant height, number of pods per plant, pod length, dry biomass weight per plant, grain yield per plant and grain yield per hectare. Highly significant differences were observed among the accessions for all traits. The grain yield per hectare was correlated positively and significantly with number of pods per plant and grain yield per plant showing a scope for simultaneous improvement of yield and yield related traits. Principal Component biplot revealed that accessions Acc2024, Acc5352, Acc2355, Acc4565, Glenda and L-cwp3 were the most genetically distinct accessions and can serve as potential candidate parental lines for hybridization to achieving transgressive segregation population in breeding programmes. [ABSTRACT FROM AUTHOR]

Cultivar development of cowpea with increased grain yield depends on evaluation and selection of genetically unique and complementary breeding lines. The objective of this study was to evaluate cowpea collections using agronomic traits to select promising parents to develop breeding population. Twenty-two cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. Analysis of variance revealed significant genotypic (G) and locations (L) differences for all agronomic traits evaluated. Significant differences were also observed for most of the traits due to G X L, G X Year (Y), L X Y and G X L X Y interactions effects. The genotypes tested at two locations showed considerable genetic variation for the following agronomic traits that varied for number of leaves (NL) (20.08-179.78), leaf length (LL) (12.36-67.72 cm), leaf width (LW) (4.78-22.02 cm), number of branches (NB) (6.81-13.85), number of pods per plant (NPPP) (14.33-54.04), number of seeds per pod (NSPP) (11.7286.28), pod diameter (PD) (5.75-22.73 mm), plant height (PH) (6.57-233.71 cm), pod length (PL) (3.94-100.92 mm), hundred seed weight (HSWt) (8.11-49.52 g) and grain yield (GY) (0.10-1.48 t ha−1). Grain yield was significant and positively correlated with all of the traits except leaf length. The principal component analysis (PCA) identified four principal components (PCs) contributing to 73.62% of the total explained variation amongst the tested genotypes. The selected cowpea genotypes for most of agronomic characteristics are useful and candidate genetic resources for the development of breeding population in cowpea breeding and enhanced production and productivity for food and nutrition in the country. [ABSTRACT FROM AUTHOR]

Taro [Colocasia esculenta (L.) Schott] is an important underutilised staple food crop in South Africa, with a lot of potential to address food insecurity among poor rural households. Development of high yielding stable taro cultivars is one of the most important goals of plant breeders. Twenty-nine taro accessions collected from major taro producing regions of the country were evaluated for growth performance, yield potential and stability under dryland conditions at two sites (Umbumbulu and Roodeplaat) in 2013, 2014 and 2015 cropping seasons. The experiment was laid in a randomised complete block design replicated three times. Growth and yield traits were measured. Analysis of variance and correlation analysis was done on all measured traits. The genotype by environment interaction was analysed using additive main effects and multiplicative interaction (AMMI). As a result, significant variation was observed for most of the traits except number of leaves and leaf width as well as number of suckers, while all the traits showed significant variation for location by year interaction. Number of corms showed significant variation for location by year by genotype interaction among all the traits evaluated. Genotype effect was highly significant (p < .01) on plant height, corm length, number of corms and significant (p < .05) on yield. The significant difference between genotypes for these traits proves that there was a genetic variability and there is a scope for selection. The correlation study also reveals that majority of the characters were positively correlated with each other. Total yield was positively and highly significantly (p < .01) correlated with all the measured traits. AMMI was effective in identifying stable genotypes. The top ranking cultivars per environment may be considered for cultivation under the specific environment, the stable cultivars may be considered for cultivation across all the taro growing regions. [ABSTRACT FROM AUTHOR]

Grain legumes, including cowpea, are the cheapest sources of minerals and protein to enhance human nutrition. Cultivar development and deployment of cowpea with increased grain mineral content and protein composition rely on selection of genetically unique and complementary breeding lines. The objective of this study was to assess the grain minerals and protein composition of diverse cowpea collections of eastern, southern and western Africa to select promising parents to develop a breeding population. Twenty-two genetically diverse cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. The dried grain mineral contents were determined using an Atomic Absorption Spectrophotometre, while the protein content was determined by the combustion method. Analyses of variance showed significant (P < 0.05) effects of genotypes, locations and their interactions. The test genotypes showed considerable variation for the following nine mineral contents: calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varying from 0.07 to 0.12 mg kg−1; 4.46 to 7.81 mg kg−1; 0.06 to 0.11 g; 11.82 to 14.45 g; 1.86 to 2.27 g; 9.24 to 13.30 mg kg−1; 0.26 to 0.80 g; 4.63 to 5.92 g and 0.03.00 to 0.05 g, respectively. Further, the total protein content varied from 23.16 to 28.13%. Significant correlations were detected among some mineral elements and total protein content, suggesting the possibility of simultaneous selection for these traits. The principal component analysis (PCA) identified four principal components (PCs) contributing to 70.93% of the total explained variation amongst genotypes. Overall the following genotypes with desirable grain mineral and protein attributes were selected: IT90K-59 (Ca), 98K-5301 (Ca and protein), ITOOK-1060 (Cu), ITOOK-1217 and IT845-2246 (Fe), Bensogla (K, Na, and P), TVU11424 and ITOOK-1217 (Mg), CH14 (Mn and Na), TVU12637 (Mn) and Glenda and Vuli (Zn). The selected cowpea genotypes are useful genetic resources for population and cultivar development for grain nutrients composition. [ABSTRACT FROM AUTHOR]

Cowpea is indigenous to the African continent and is grown for its leaves and grain in different countries of the world. The objective of this study was to determine the variability and heritability of mineral and crude protein contents in the leaves of selected cowpea genotypes grown in South Africa. The trials consisted of twenty five cowpea genotypes evaluated for two cropping seasons. The combined mean values showed wide genetic variation in the mineral elements evaluated. The mean values of calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varied from 2.23 to 3.69 mg·kg-1; 6.96 to 14.15 mg·kg-1; 311.30 to 1049.95 mg·kg-1; 1.13 to 1.74 mg·kg-1; 0.36 to 0.70 mg·kg-1; 130.08 to 186.42 mg·kg-1; 126.62 to 307.87 mg·kg-1; 0.27 to 0.39 mg·kg-1; and 27.76 to 43.55 mg·kg-1, respectively. The total protein content varied from 21.39% to 33.45%. The correlation analysis revealed significant degree of association between and among mineral elements and total protein content. Biometrical analysis revealed that the phenotypic variances were higher than the genotypic variances. High values of heritability estimates were also recorded for most of the evaluated traits. The principal component analysis (PCA) showed that the first three principal components contributed 71.93% of total variation among the genotypes. The study revealed that there is an ample genetic variability that can be exploited for use in breeding for nutritional quality in cowpea leaves. [ABSTRACT FROM AUTHOR]

Physiological and complementary phenotypic traits are essential in the selection of drought-adapted crop genotypes. Understanding the physiological response of diverse okra genotypes under drought stress conditions is critical to the selection of drought-tolerant accessions for production or breeding. The objective of this study was to assess the levels of drought tolerance in preliminarily selected okra accessions based on leaf gas exchange and chlorophyll fluorescence to determine best-performing genotypes for drought-tolerance breeding. Twenty-six genetically diverse okra accessions were screened under non-stressed (NS) and drought-stressed (DS) conditions under a controlled glasshouse environment using a 13 × 2 alpha lattice design in three replicates, in two growing seasons. Data were subjected to statistical analyses using various procedures. A significant genotype × water condition interaction effect was recorded for transpiration rate (T), net CO2 assimilation (A), intrinsic water use efficiency (WUEi), instantaneous water use efficiency (WUEins), minimum fluorescence (Fo′), maximum fluorescence (Fm′), maximum quantum efficiency of photosystem II photochemistry (Fv′/Fm′), the effective quantum efficiency of PSII photochemistry (ɸPSII), photochemical quenching (qP), nonphotochemical quenching (qN) and relative measure of electron transport to oxygen molecules (ETR/A). The results suggested variable drought tolerance of the studied okra accessions for selection. Seven principal components (PCs) contributing to 82% of the total variation for assessed physiological traits were identified under DS conditions. Leaf gas exchange parameters, T, A and WUEi, and chlorophyll fluorescence parameters such as the ɸPSII, Fv′/Fm′, qP, qN, ETR and ETR/A had high loading scores and correlated with WUEi, the ɸPSII, qP and ETR under DS conditions. The study found that optimal gas exchange and photoprotection enhance drought adaptation in the assessed okra genotypes and tested water regimes. Using the physiological variables, the study identified drought-tolerant accessions, namely LS05, LS06, LS07 and LS08 based on high A, T, Fm′, Fv′/Fm′ and ETR, and LS10, LS11, LS18 and LS23 based on high AES, Ci, Ci/Ca, WUEi, WUEins, ɸPSII and AES. The selected genotypes are high-yielding (≥5 g/plant) under drought stress conditions and will complement phenotypic data and guide breeding for water-limited agro-ecologies. [ABSTRACT FROM AUTHOR]

Bambara groundnut (Vigna subterranea [L.] Verdc.) is a nutritionally rich grain legume crop indigenous to Africa. It is tolerant to drought stress and has become adapted to grow under low input and marginal agricultural production systems in Africa and Asia. Bambara groundnut is an orphan crop, and represents a neglected and under researched plant genetic resource. Modern crop management, production technologies, and value chains are yet to be developed in Africa to achieve the potential economic gains from Bambara groundnut production and marketing. In sub-Saharan Africa (SSA) the production and productivity of Bambara groundnut is low and stagnant because of diverse abiotic and biotic stresses and socio-economic constraints. Improved crop management and post handling technologies, modern varieties with high yield and nutritional quality, value addition, and market access are among the key considerations in current and future Bambara groundnut research and development programs. This paper presents progress on Bambara groundnut production, utilization, and genetic improvement in SSA. It presents the key production constraints, genetic resources and analysis, breeding methods and genetic gains on yield, and nutritional quality and outlook. The information presented will guide the sustainable production and effective breeding of the crop in order to pursue food and nutrition security, and improve livelihoods through Bambara groundnut enterprises. [ABSTRACT FROM AUTHOR]

Genetic diversity analysis of crop genetic resources is a prerequisite for parental selection with suitable and complementary profiles for breeding. The objectives of this study were to determine genetic diversity present among okra accessions using simple sequence repeat (SSR) and complementary phenotypic markers and to select genetically divergent and superior parental accessions for pre-breeding. Twenty-six preliminarily selected okra accessions were assessed using nine highly polymorphic SSR markers and phenotyped under drought-stressed (DS) and non-stressed (NS) environmental conditions using a 13 × 2 alpha lattice design with two replications. Data were collected on the following eleven phenotypic traits: plant height (PH), days to 50% maturity (DTM), fresh pod length (FPL), dry pod weight (DPW), dry pod length (DPL), number of pods per plant (NPPP), pod yield per plant (PYPP), total above-ground biomass (AGB), harvest index (HI), root weight (RW), and root to shoot ratio (RSR). The SSR markers revealed an expected mean heterozygosity value of 0.54, indicating moderate genetic diversity among the tested okra accessions. Cluster analysis based on phenotypic and SSR markers differentiated the accessions into three distinct genetic groups. Wide phenotypic variation was observed for PH, FPL, NPPP, and PYPP under NS and DS conditions. PYPP was positively and significantly correlated with FPL (r = 0.81), ABG (r = 0.69), and HI (r = 0.67) under DS conditions, and FPL (r = 0.83) and AGB (r = 0.60) under NS conditions. Genetically complementary accessions such as LS04, LS05, LS06, LS07, LS08, LS10, LS11, LS15, LS18, LS23, LS24, and LS26 were identified for their high yield potential and related yield-improving traits under DS conditions. The identified accessions are recommended as parents for hybridization and selection programs to improve the yield potential of okra under drought-stressed environments. [ABSTRACT FROM AUTHOR]

Bambara groundnut is a highly nutritious underutilized legume crop, which can be cultivated in unfavorable environments, has the potential to address food security and can significantly contribute to climate-smart agriculture. The objectives of this study were to determine the phenotypic diversity and characterize a southern African bambara groundnut germplasm collection for grain yield and yield components, to identify superior bambara accessions and to determine the correlation between measured traits. The 100 bambara accessions were planted in two different locations over two seasons. There was significant variability among the accessions, locations, seasons and their interactions for all traits. Low broad-sense heritability values (<0.5) were observed for almost all traits. Significant positive correlations between all measured traits were observed. High-yielding accessions; WS 42 (AS), MV 67-1, K 5, AS 9, SCORE 1 and SB 12-3 were identified. Bambara accessions 224 (RF-7684), 179 (AB 16-5C), 121 (Red Ex Zimbabwe), 62 (SB 8-3), 9 (SB 4-1), 181 (SB 8-1B), 89 (AS 20), 217 (RF-6221), 94 (K 5), 177 (S1 Sel2) and 74 (AS 5) were associated with a high grain yield, plant spread and plant height. These accessions could be used as potential parents in a breeding program for the development of high-yielding varieties. [ABSTRACT FROM AUTHOR]

• Drought tolerance was assessed among 26 okra genotypes using phenotypic traits • Phenotypic variation was observed among assessed okra genotypes under drought stress condition • Positive correlations were recorded between fresh pod yield with fresh pod length, dry pod weight and number of pods per plant • The study identified genotypes such as LS01, LS06, LS09, LS17, LS18, LS19, LS21, LS22, LS24 and LS26 for production and breeding Genetic variation is fundamental for breeding drought-adapted cultivars with economic traits. The objective of this study was to determine the response of selected okra genotypes to drought stress using yield and yield-related traits to identify and select candidate genotypes for drought tolerance breeding. Twenty-six okra genotypes were evaluated in glasshouse (GH) and field (FLD) environments under drought-stressed (DS) and non-stressed (NS) conditions using a 13 × 2 α lattice design with two replications. Data were collected on the following phenotypic traits: number of branches per plant (NB), plant height (PH), days to maturity (DTM), stem diameter (SD), fresh pod length (FPL), dry pod weight per plant (DPW), dry pod length per plant (DPL), number of seeds per plant (NSP), number of pods per plant (NPP), pod yield per plant (YPP) and anthocyanin (ATY) pigmentation of the stem. Significant (P < 0.05) genotype x testing environment x water condition interaction effects were recorded for most traits allowing for selection of okra genotypes suited for drier conditions. YPP positively and significantly correlated with FPL (r = 0.66; P ≤ 0.001), DPW (r = 0.80; P ≤ 0.001) and NPP (r = 0.58; P ≤ 0.001) under DS condition in the FLD environment. The study identified genotypes with high yield and other desirable phenotypic attributes which are useful genetic resources for future crosses and selection of promising progenies based on combining ability analysis and heritability under water-limited environments. [ABSTRACT FROM AUTHOR]

• Okra is high-valued vegetable crop serving the food, pharmaceutical, paper and oil industry. • Okra production and productivity in sub-Saharan Africa and globally are hindered by a lack of improved cultivars with drought tolerance. • The extensive phenotypic and genotypic variation in okra genetic resources are useful for cultivar development with enhanced seed and oil yields, and drought tolerance. Okra (Abelmoschus esculentus L. Moench) is high-valued vegetable and oil crop serving the food, pharmaceutical, paper and oil industry. The production of okra in sub-Saharan Africa (SSA) and globally are hindered by a lack of improved cultivars with drought tolerance. Considerable phenotypic and genotypic variation present in okra genetic resources from SSA is useful for cultivar design with enhanced pod and oil yields, and drought tolerance. However, the genetic diversity present in SSA's okra germplasm collection is yet to be explored for breeding targeting economic and horticultural traits. The objective of this review was to document the research progresses on phenotypic and genotypic divergence analysis and drought tolerance breeding of okra to facilitate breeding and conservation. The review presented the diversity of okra for key agronomic, horticultural and physiological traits for ideotype breeding, gene introgression and drought tolerance improvement. This is followed by key summaries on genetic diversity using conventional and genomic tools, and use of genetic variation in selection programs involving drought-adaptive and economic traits. The review serves as a baseline information to guide future okra breeding and cultivar design under water limited environments in SSA or related agro-ecologies. [ABSTRACT FROM AUTHOR]

• Several landraces of bambara groundnut (Vigna subterannea (L.) Verdc) exist in South Africa which are but, the most underutilized and un-researched legumes. • There is variations in the bambara groundnut landraces to the nodulation responses to a given species of rhizobium. • Bambara groundnut have promiscuous nodulation properties with different rhizobia species and host specificity rule does not apply for these legumes. • Bambara groundnut exhibit more symbiotic interaction with Rhizobia species belonging to the cowpea miscellany group. Bambara groundnut (Vigna subterranea) is one of the most underutilized and neglected legume crop used for human consumption worldwide. Unlike the common food and forage legumes, the symbiotic properties of this legume have not been studied sufficiently. This study is designed to investigate the nodulation compatibility and symbiotic performance of twelve landraces of V. subterranea with five different Rhizobia species isolated from the nodules of other legumes under glasshouse conditions. Pre-germinated seeds of each landrace planted in sterile river sand medium were inoculated with 108 cfu/ml of each rhizobium inoculum suspension and monitored with regular watering using nitrogen free Hoagland's solution for six weeks. The taxonomy and phylogeny of the five rhizobia species was determined using nucleotide sequence analysis of the 16S rRNA and recA (DNA recombination protein) genes. A concatenated multiple sequence alignment was used to construct an MLSA tree to further analyze the phylogeny of the strains. Significant differences were observed among individual bambara genotypes and rhizobia strains in terms of nodule numbers and dry weight, as well as plant biomass. Statistical analysis showed that Rhizobia strains XBD2 and XS34 identified as Bradyrhizobium zhangiangens and B. centrosematis respectively exhibited the highest nodulation compatibility in terms of nodule number and nodule dry weight with one or more bambara groundnut landraces. This study demonstrated that V. subterannea does not show preference to unique rhizobia, confirming that they are promiscuously nodulated by more than one species of rhizobium belonging mainly to the cowpea miscellany cross inoculation group. The findings of this study also provide insights into the selection and development of appropriate low cost rhizobia inoculants in the sustainable production of this underutilized legume for use by smallholder farmers in South Africa. [ABSTRACT FROM AUTHOR]

The growth and yield characteristics of six accessions (Amadumbe 2914, Amadumbe 3053, Amadumbe 43, Amadumbe 56, Amadumbe Amzam 3553/5118 and Amadumbe 2919) of Colocasia esculenta (taro) were compared in the Western Cape Province of South Africa. A randomized complete block design with five replications was used. Differences in growth and yield observed among the accessions may be attributed to non-uniformity in the size of the propagules used for establishment of the trial, genotypic and/or climatic factors. Amadumbe 2914, Amadumbe 3053, Amadumbe 43 and Amadumbe 56, established with bigger cormels (20.37 - 28.33 g) consistently showed superiority in terms of plant height, leaf area and yield over Amadumbe Amzam 3553/5118 and Amadumbe 2919, established with smaller cormels (15.00 and 16.67 g). However, there was no appreciable difference in the size and weight of individual cormels produced by all six accessions. Due to small cormel sizes, a higher proportion (about 92%) of the cormel yield could be classified as unmarketable. Good nutrition can be provided by the leaves and tubers, even though maximum yield may not be attained in the Western Cape due to temperature, radiation and day length limitations, especially in winter. Continued research to determine whether yield can be improved with better nutrition and agronomic practices, is warranted. [ABSTRACT FROM AUTHOR]

Bambara groundnut is a highly nutrient dense underutilized orphan crop, and has the potential to address malnutrition and food security. The study objectives were to estimate the variation in the concentration of protein, starch, amylose, iron (Fe), zinc (Zn), phytic acid (PA) and mineral bioavailability, to identify superior bambara accessions and to determine the interrelationship between measured traits. and methods: Grain samples were collected from 59 accessions that were planted in two different locations over two seasons and used to measure the nutritional quality traits. Results: Significant variability among accessions in diverse locations and seasons for protein, Fe, Zn, and PA/Fe and PA/Zn ratios was observed. The average values of measured characteristics were protein (22.59 %), starch (36.52 %), amylose (21.15 %), Fe (38.83 mg kg−1), Zn (27.10 mg kg−1), PA (6239.24 mg kg−1), PA/Fe (17.74) and PA/Zn (22.87) content. Significant positive correlations between protein, Fe and Zn were observed and these traits were negatively correlated with starch, amylose, PA, PA/Fe and PA/Zn ratio. Accessions SB 4–4 A and M 3 were superior for more than one nutritional trait and had good mineral bioavailability. Superior accessions can be used as potential parents for the development of nutritionally improved bambara cultivars. • Bambara groundnut has a potential to address malnutrition and undernourishment. • Significant seasonal variation for Fe, Zn, and ratios of phytic acid with Fe and Zn. • Significant positive correlations between Fe, Zn and protein content. • Negative correlations between starch and protein content. • Significant location variation for Fe, and ratios of phytic acid with Fe and Zn. [ABSTRACT FROM AUTHOR]

This work is the first report on the isolation and structural elucidation of xylan from bambara and cowpea biomass. The xylans, isolated using acidic delignification followed by NaOH extraction method gave 12.3% and 13.6% yield, respectively. 1H NMR analyses revealed that both the xylans were glucuronoxylan. The presence of xylose and glucuronic acid was confirmed by monosaccharide analysis and uronic acid assay. Further, xylooligosaccharide production from bambara and cowpea xylans was carried out using xylanase from three different glycoside hydrolase families, and the products were analyzed by TLC and MALDI-ToF MS. The hydrolysis products of both xylans resembled hardwood glucuronoxylan fragments, generated under similar conditions. The most common oligosaccharides observed in the hydrolysates were Xyl 2 , Xyl 3 , MeGlcA3Xyl 3 , MeGlcAXyl 4 and MeGlcAXyl 5. A series of computational approaches were also used to study the interactions of the three different xylanases with xylan. Thus, untapped biomass such as bambara and cowpea could serve as a potential source for xylan which could further be converted to xylooligosaccharides and many other value-added chemicals. • First report on xylan extraction from bambara and cowpea biomass. • Investigation on bambara and cowpea xylan as a potential source for XOS production. • First report on the properties of XOS products from these agro-residues. • New insights into the xylanase-xylan complex were achieved in silico. [ABSTRACT FROM AUTHOR]

The genus Corchorus includes nutrient-rich indigenous leafy vegetables often grown or harvested in the wild in Africa. It has potential to contribute to food security, but there is need to improve it as a crop through plant breeding. However, not much is known about the genetic variability among Corchorus species. The aim of this study was thus to characterise the available germplasm of Corchorus accessions and investigate heritability of their agro-morphological traits. Eleven Corchorus accessions (4 South African and 7 from the World Vegetable Center) were evaluated in a field study at Roodeplaat, South Africa, for their morpho-agronomic traits using a randomised complete block design with three replications across two seasons (2015/2016 and 2016/2017). Data were subjected to ANOVA, principal component analysis and cluster analysis. Broad sense heritability, genetic advance, genetic parameters and correlations were determined among the accessions and traits. The Corchorus accessions showed significant (P <.05) differences in all the quantitative traits evaluated. The data showed significant variability among the studied Corchorus accessions in their agro-morphological traits for exploitation in future breeding programmes that in turn can contribute to the improvement of this crop. [ABSTRACT FROM AUTHOR]

Biostimulant application during the cultivation of underutilized crops is an environmental-friendly approach for their production and utilization to promote food security and human health. This study investigated the effect of two commercial biostimulants (a seaweed-based extract, Kelpak® (1:100, 1:40, and 1:20, dilutions), and plant growth promoting rhizobacteria, PGPR (1:5, 1:10, and 1:15, dilutions)) on the growth, yield, phytochemical content, and nutritional quality of five selected Abelmoschus esculentus genotypes. Biostimulant application significantly influenced vegetative growth and yield in a dose-dependent manner. Plant height, chlorophyll content, stem diameter, number of pods, and total pod fresh and dry weights increased with a decrease in dilution of the biostimulants. The application of PGPR (1:5) significantly promoted both the vegetative growth (plant height, chlorophyll content, and stem diameter) and yield (number of pods, total fresh weight, and total dry weight) when compared to the control (untreated plants) and other biostimulant dilutions. Genotype and biostimulant application had an interactive effect on all the phytochemical (total phenolics, flavonoids, and condensed tannins) and nutritional (β-carotene, vitamin C, calcium, iron, potassium, magnesium, sodium, and zinc) qualities evaluated. This study demonstrated the differential effect of biostimulant application on A. esculentus genotypes. These biostimulants can be used to enhance growth, yield, biochemical, and nutritional contents of underutilised crops such as A. esculentus, depending on the crop genotype, in order to improve crop productivity and combat food insecurity especially in food insecure communities. [ABSTRACT FROM AUTHOR]