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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]

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]