Bambara Groundnut Accessions Research Articles

Estimates of Phenotypic and Genotypic Variance and Heritability in Eighty-Nine Bambara Groundnut [Vigna subterranea (L.) Verdcourt] Accessions Collected from Six Regions of Niger

The bambara groundnut [Vigna subterranea (L.) Verdc. (Fabaceae)] is a legume mainly cultivated by women, for the nutritional quality of these seeds. It is a so-called minor culture and the improvement of the plant and its popularization remains to be promoted. The objective of this present work is to evaluate the genetic variability of bambara groundnut accessions. The experiment was carried out according to a completely randomized block device with four replications. Twenty-two (22) characters including four (4) phenological, four (4) morphological and fourteen (14) related to yield were evaluated for accessions characterization. Descriptive analysis showed significant differences. The coefficients of variation ranged from 3.51% (maturity date) to 38.87% (shell weight). Significantly high values (CV˃20%) for 8 of the metric parameters were observed. Pod weight per plant and seed weight per plant (r=0.943), yield in kg/ha (r=0.943); seed weight per plant and yield in kg/ha (r=0.999) showed the strongest correlations. The phenotypic and genotypic coefficients of variation were high for dry biomass weight (PCV=42.23%; GCV=28.40%), shell weight (PCV=63.46%; GCV=22.46%) and 100-seed weight (PCV=25.57%; GCV=25.25%). Maturity date (95.77%) and 100-seed weight (99.84%) had high heritabilities. Broad-sense heritability and genetic gain are high for 100-seed weight (H2=99.84%; GA=52.58%). The Ascending hierarchical classification produced four groups of which group 4 is the most efficient in yield with short (20.58cm) early accessions (80.32 days). Groups 1 and 2 include, late accessions (~22cm) with respectively maturity dates (DM=85.67 days and DM=86.53 days.

Morphometric diversity of some Nigerian accessions of Bambara groundnut (Vigna subterranea)

AbstractThis study evaluated the morphological diversity of some Nigerian accessions of Bambara groundnut. Field experiments were conducted in Nigeria in two locations and the phenotypic variation of Bambara groundnut accessions evaluated in 3 years (2017–2020) using a randomized complete block design. Twenty-eight quantitative and 10 qualitative traits were observed. Twenty-three out of the 28 quantitative morphological traits showed significant differences. TVSu-589 (28.85) and TVSu-670 (28.57) had the highest plant height; TVSu-572 (121.52), TVSu-271 (113.10) and TVSu-336 (104.15) had the highest 100-seed weight. Genetic variations were also observed in seed colour, terminal leaflet shape, petiole colour and eye pattern. Principal component analysis showed PC1 constituting 23.36% and PC2 constituting 15.76% of the total variation, while the first eight principal components with eigenvalues ≥1 revealed 77.28% of the total variation. Cluster analysis grouped the accessions into four groups. Based on yield data in this study, accessions TVSu-594, TVSu-350, TVSu-336, TVSu-1242, TVSu-129, TVSu-14, TVSu-179, TVSu-2100, TVSu-261 and TVSu-589 were the best for yield and are recommended for further evaluation to improve yield. This study showed that a wide range of diversity exists in Bambara groundnut of Nigerian origin that could be useful for further utilization of genetic resources and improvement.

Evaluation of eight bambara groundnut (Vigna subterranea (L.) Verdcourt) accessions for agronomic characters and proximate composition in Uyo, Akwa Ibom State, Nigeria

Bambara groundnut (Vigna subterranea [L.] Verdc.) is a valuable but underutilised legume crop grown in sub-Saharan Africa. The objective of this study was to evaluate the yield and yield components of eight Bambara groundnut accessions obtained from the National Root Crops Research Institute in Umudike, Nigeria. The experiment was conducted at the Teaching and Research farm of the University of Uyo, Uyo Southern Nigeria during the 2021 cropping seasons, using a randomised complete block design with three replications. Growth, yield and nutritional parameters were collected and subjected to analysis of variance, correlation and principal component analysis. Plant height, number of leaves, and leaf area were all significantly different (P≤0.05) among the accessions three months after planting. Number of pods per plant, seed weight, and 100-seed weight differed significantly (P≤0.05). Caly PSC (2853 kg/ha), Caly SK 46 (2803 kg/ha), Zeina (2538 kg/ha), and BNT (2488 kg/ha) were the top yielders among the accessions. Yields of Bambara groundnut differ significantly (P≤0.05) between accessions studied, ranging from 1624.67 kg/ha to 2853.33 kg/ha. Principal component (PC) analysis identified eight influential components, two of which, PC1 and PC3, contributed 27% and 17% of the total variation, respectively. In this study, the correlation analysis revealed that plant height and petiole length, plant height and number of seeds per plot were all negatively correlated. The leaf area and the number of pods per plot, the number of seeds per pod and the fibre content, the leaf area and seed weight, and the plant height and seed weight were all noted positively correlated. The nutritive value of the eight Bambara groundnut accessions varied significantly (P≤0.05). The mean protein levels of eight Bambara nut accessions studied ranged from 18.82 to 20.39%. Findings from this study clearly indicate that Bambara groundnut is suitable for production in Uyo, Akwa Ibom State. Thus, high yielding accessions identified in this study are recommended for increased production in Akwa Ibom State of Nigeria.

Yield response of accessions of Bambara groundnut (Vigna subterranea (L) Verdc) inoculated with Bradyrhizobium japonicum strains

Field experiments were conducted in two different agroecological locations of Ibadan and Ikenne in Nigeria from August through December during the 2019 and 2020 cropping seasons. The studies were set up to reduce reliance on inorganic nitrogen fertilizer and to embrace the use of nitrogen-fixing bacteria to improve legume production to increase farmers' output and profitability. Ten accessions of the Bambara groundnut (BGN) were used in the trials. Seeds of each BGN accession were coated with each of the following Bradyrhizobium japonicum strains (B. japonicum): FA3, RACA6, USDA110, and IRJ2180A before planting. Furthermore, Nitrogen (N) fertilizer (20 kg/ha, urea) was applied to seedlings without inoculation, and uninoculated seedlings (without inoculation and without fertilization) served as control. The experiment was, therefore, a factorial arrangement (10 BGN accessions, 4 B. japonicum strains, N fertilizer application, and an uninoculated control). The yield and yield components of the inoculated BGN accessions were significantly enhanced at both agroecological locations and seasons. Among the B. japonicum strains used for inoculation, RACA6 strains significantly enhanced the yield and yield component of TVSu-1698 than other inoculated BGN accessions with a mean value of 6,234 ± 87 kg ha−1 recorded in both locations and seasons, compared to the result obtained in the combination of TVSu-1698 with N fertilizer with a mean value of 3,264 ± 943 kg ha−1. By using TVSu-1698 with RACA6 strain, farmers can get 85% more yield than on average with other genotypes/strains combination, while an average yield of 60% could be obtained by farmers using N fertilizer application.

AMMI and GGE biplot analyses of Bambara groundnut [Vigna subterranea (L.) Verdc.] for agronomic performances under three environmental conditions.

The two most common styles to analyze genotype-by-environment interaction (GEI) and estimate genotypes are additive main effects and multiplicative interaction (AMMI) and genotype + genotype × environment (GGE) biplot. Therefore, the aim of this study was to find the winning genotype(s) under three locations, as well as to investigate the nature and extent of GEI effects on Bambara groundnut production. The experiment was carried out in the fields of three environments with 15 Bambara groundnut accessions using the randomized complete block design (RCBD) with three replications each in Ibadan, Osun, and Odeda. Yield per plant, fresh seed weight, total number of pods per plant, hundred seed weight, length of seeds, and width of seeds were estimated. According to the combined analysis of variance over environments, genotypes and GEI both had a significant (p < 0.001) impact on Bambara groundnut (BGN) yield. This result revealed that BGN accessions performed differently in the three locations. A two-dimensional GGE biplot was generated using the first two principal component analyses for the pattern of the interaction components with the genotype and GEI. The first two principal component analyses (PCAs) for yield per plant accounted for 59.9% in PCA1 and 40.1% in PCA2. The genotypes that performed best in each environment based on the "which-won-where" polygon were G8, G3, G2, G11, G6, and G4. They were also the vertex genotypes for each environment. Based on the ranking of genotypes, the ideal genotypes were G2 and G6 for YPP, G1 and G5 for FPW, G15 and G13 for TNPP, G3 and GG7 for HSW, G7 and G12 for LOS, and G10 and G7 for WOS. G8 was recorded as the top most-yielding genotype. G8, G4, G7, and G13 were high yielding and the most stable across the environments; G11, G14, and G9 were unstable, but they yielded above-average performance; G14, G12, G15, and G1 were unstable and yielded poorly, as their performances were below average. Bowen was the most discriminating and representative environment and is classified as the superior environment. Based on the performance of accessions in each region, we recommend TVSU 455 (G8) and TVSU 458 (G3) in Bowen, TVSU 455 (G8) and TVSU 939 (G6) and TVSU 454 (G1) in Ibadan, and TVSU 158 (G2) and TVSU 2096 (G10) in Odeda. The variety that performed best in the three environments was TVSU 455 (G8). They could also be used as parental lines in breeding programs.

Molecular Genetic Diversity in Bambara groundnut [Vigna subterranea (L.) Verdc] Assessed by Microsatellite Markers

Bambara groundnut is a valuable leguminous crop with many landraces. A study was carried out to establish genetic diversity and phylogenetic relationship, among 33 Bambara groundnut accessions based on simple sequence repeat (SSR) markers. The nine microsatellite markers amplified a total of 27 alleles with a mean of 6.00 alleles per locus. Marker P 36 had the highest number of polymorphic bands while makers P131 and P68 were monomorphic. Genetic distance among the accessions based on Jaccard’s similarity coefficient ranged from 0.84 to 1.00. Cluster analysis resolved the accessions into five major groups with subgroups. Each group had a combination of distinct accessions from different geographical origin. A substantial level of intra-accession polymorphism was obtained among the evaluated collection of Bambara groundnut. The significant genetic diversity observed can support the selection of appropriate parental genotypes for the improvement of Bambara groundnut through various breeding programmes.

Phenological, Morphological and Agronomic Characterization of Bambara Groundnut Genotypes on Plinthite Soil in East-centre Area, Burkina Faso

Bambara groundnut has long been a neglected and understudied crop. Thanks to the new orientations for the développement of agriculture and achievement of food security in Burkina Faso, in recent years, studies on Bambara groundnut have experienced renewed interest. Despites nutritional, agronomic and socio-economic importance and some studies carried out on this crop. The diversity within Bambara groundnut cultivated remains poorly understood. The objective of this study was to assess phenological morphological and agronomic characterization of 20 Bambara groundnut accessions from National Institute for the Environment and Agricultural Research (INERA) genebank. The experimental device used was a completely randomized Fisher blocks with four replications on the site of University Centre of Tenkodogo. These accessions were evaluated on 23 morphological characters including four qualitative characters and 19 quantitative characters. Qualitative traits showed high proportion of oval terminal leaflet shape (70%), cream coloured seeds (45%) and 80% presence of eyes of various shapes and colours. The analysis of quantitative characters showed all the characters are discriminating except the plant spread (PlS) at the 5% treshold with regard to morphological, physiological and agronomic traits and low coefficient of variation (CV) values for the different phenological characters, except for the number of days from sowing to 50% plantlet emergence (EMG50). Pearson correlation matrix indicated positive and negative correlation. Most of the negative correlation was observed between phenological and agronomic traits The dendrogram showed organization of the variability in three different groups on the basis of the physiological, phenological and agronomic traits. The variability expressed among INERA gene bank genotypes showed important variability, which can be exploited in Bambara groundnut breeding programs using the clustering and associations of characters.

Yield Components and Yield Stability Performance of Some Nigerian Accessions of Bambara Groundnut [Vigna subterranea (L.) Verdc.] in Six Environments

Background: Bambara groundnut accessions over the years had been unstable in its yield potentials with contrasting yield inferences, factors not limited to variety, soil types and nutrients, climate change, time had been bottlenecks for scientist to breakthrough in stability research. Field experiments were conducted in three years at two locations to assess and identify accessions with stable yield and determine the relationship between yield and yield components. Methods: Seeds of 100 accessions of Bambara groundnut of Nigerian origin were obtained from the genebank of the Genetic Resources Center, IITA in 2017. Randomized complete block design (RCBD) was used in the evaluation for three years in two locations. PROC ANOVA procedure on the statistical analytical system (SAS, 9.4) was used to determine significant differences and stability equation was used to identify yield stable index. Result: Correlation showed that seven yield contributing traits had positive and significant correlation with yield per hectare. Yield stability analysis indicated nine of the selected accessions were stable in the expression of its yield potentials in the environments and years. This study showed that selection for high yielding and stable accessions could be useful for further utilization of genetic resources in achieving food security.

Variations of Nutrient and Antinutrient Components of Bambara Groundnut (Vigna subterranea (L.) Verdc.) Seeds

Bambara groundnut (BGN) fits the bill when it comes to an acceptable level of nutrient and mineral composition. BGN is a balanced food that can help eradicate food and nutritional insecurity if it is incorporated into the major food system. However, there is a large degree of variation in nutrient composition and antinutritional factors among BGN accessions. Here, we show the degree of variability of nutrient and antinutrient components such as percentage ash, moisture, protein, fat, tryptophan, tannin, and phytate contents in seeds of 95 accessions of BGN. Data were subjected to analysis of variance (ANOVA), followed by correlation and principal component analysis. Clustering was done to show the relatedness between the accessions in response to the various traits. A high level of heterogeneity was observed among the accessions for the various traits studied. PC1 and PC2 show 41.2% of the total observed variations. Cluster analysis grouped accessions into four main clusters. This study was able to confirm the high level of diversity in the components of nutrients and antinutrients previously reported in BGN. The results of this study are expected to aid in identifying parent lines for improved breeding programs.

Variation in protein content, starch components, selected minerals and their bioavailability in bambara groundnut accessions

IntroductionBambara 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. Materialsand 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. ConclusionSuperior accessions can be used as potential parents for the development of nutritionally improved bambara cultivars.

Genetic diversity and population structure of some Nigerian accessions of Bambara groundnut (Vigna subterranea (L.) Verdc.,) using DArT SNP markers

Bambara groundnut is one of the crops with inadequate molecular research to show its full potentials. Previous studies showed morphological diversity with inadequate information to confirm genetic variations. In the quest to reveal the genetic potentials, deoxyribonucleic acid (DNA) of the selected accessions was extracted through leaf samples at 3 weeks old, using Dellaporta Miniprep for Plant DNA Isolation procedure. The high quality DNA was sequenced using Diversity Arrays Technology (DArT) markers to unlock diversity among Bambara groundnut of Nigerian origin. Cluster analysis (neighbor-joining clustering) of the single nucleotide polymorphisms (SNP’s) were used to generate sub-population to show relatedness and differences. Seven sub-populations were generated with 5927 (50.13%) high quality DArT markers out of the 11,821 SNPs generated. This revealed high genetic diversity existed among the selected Bambara groundnut accessions in Nigeria. This also revealed that DArT markers were highly efficient in classifying the accessions based on molecular expressions. This study also identified markers responsible for genetic variation that could facilitate the characterization of larger collections for further utilization of genetic resources and most importantly Bambara groundnut for the purpose of crop improvement.

Assessment of Genetic Diversity of Bambara Groundnut Accessions [Vigna subterranea (L) Verdcourt] in Sahelian Zone of Niger

The agro-morphological characterization of plant genetic resources is crucial to understand the phenotypic and genotypic relationships between different crop varieties. Bambara groundnut (Vigna subterranea) is a grain legume grown worldwide due to its high nutritional values, nitrogen-fixing ability, and drought tolerance. To assess the existing genotypic and phenotypic diversity within Bambara groundnut accessions and to estimate the genetic parameters guiding future varietal improvement programs, 22 Bambara groundnut accessions were characterized in the Sahelian zone of Niger. Thus, the coefficient of variation ranged from 2.42% to 48.25%, and 7 of the 22 parameters measured presented high coefficients of variation (CV˃20%). Yield had positive high correlation with shell weight (r=0.56), 100-seed weight (r=0.61), and seed weight (r=0.99). The highest GCV and PCV were observed in number of seeds per plant (PVC=35.05% and GCV=22.65%), hull weight (PVC=85.91% and GCV=25.51%) and dry biomass weight (PVC=36. 61% and GCV=23.66%), for a respective heritability and genetic gain of: (h2b=41.58%; GA=30.03%), (h2b=8.82%; GA=15.60%) and (h2b=41.76%; GA=31.49%). The highest heritability is observed in the number of leaves (92.40%) and the date of maturity (92.08%). Emergence date revealed high heritability and genetic gain (h2b=78.77% and GA=20%). Parameters with high heritability and genetic gain (h2b≥60% and GA≥20%), are the least influenced by the environment. So, direct selection for improvement of these traits may be beneficial. To authenticate genetic inequality, principal component analysis (PCA) and hierarchical ascending clustering (HAC) were performed. The results showed a great agro-morphological diversity divided into four different groups, for the studied characters. Group 3 (4 accessions) and group 1 (3 accessions) are the high yielding accessions, while group 4 (8 accessions) and group 2 (7 accessions) are the lower yielding accessions. ...................

Morphological Characterization and Diversity of Bambara Groundnuts in Uganda

Sixty nine Bambara groundnut accessions were evaluated at the National Crops Resources Research Institute (NaCRRI), Namulonge, Uganda to determine their morphological variability in a randomized complete block design with three replications. Analysis of variance showed significant (P &amp;lt; 0.01) divergence among accessions for all traits. Cluster analysis exhibited six distinct clusters with the highest intra-cluster distance (8.09) observed in cluster II and the lowest distance (0.00) in cluster VI. Maximum inter-cluster distance was observed between cluster VI and IV and minimum distance between cluster II and IV. Inter-cluster distance was much higher than intra-cluster distance suggesting a wider variability among accessions. All late maturing accessions with high yield were grouped in cluster V while early maturing accessions were grouped in cluster III. Results of principal component analysis indicated that both yield and vegetative traits were the principal discriminatory characteristics. The accessions evaluated exhibited high diversity for most traits indicating that they can be used in breeding programs to develop varieties with desirable traits.

Effect of Bradyrhizobium japonicum Strains and Inorganic Nitrogen Fertilizer on the Growth and Yield of Bambara Groundnut (Vigna subterranea (L.) Verdc) Accessions

This study was set up to compare the inoculation of Bradyrhizobium japonicum strains and the application of nitrogen (N) fertilizers (urea with 46% nitrogen) on the growth and yield of Bambara groundnut accessions. The study results suggest that the benefits of Bradyrhizobium japonicum (B. japonicum) strain inoculation are greater and that the strain could reduce reliance and the excess amount spent by farmers to procure inorganic fertilizers and avoid the negative effect of N fertilizer on the environment after its use. Field studies were conducted in two different geographical locations, in Ibadan (Ib) and Ikenne (Ik), Nigeria, during the rainy season between August and December in 2019 and 2020. The experiment was arranged in a randomized complete block design (RCBD) in both locations and seasons and was replicated three times, with each block representing each replicate. It had a 10 × 6 factorial arrangement with one block holding the 10 accessions of Bambara groundnut inoculated with four B. japonicum strains. The second block had N fertilizer application and the third control block was without inoculation or fertilizer application. The 10 accessions of Bambara groundnut used in the study were as follows: TVSu-378, TVSu-506, TVSu-787, TVSu-1606, TVSu-1698, TVSu-1739, TVSu-710, TVSu-365, TVSu-475, and TVSu-305. Six seeds of each accession were coated with each of the four B. japonicum strains, namely, FA3, USDA110, IRJ2180A, and RACA6, before planting them in the field in both locations during the rainy season. In the next block, urea as N fertilizer (46% nitrogen) was applied to the uninoculated seedlings of accessions of Bambara groundnut 2 weeks after planting (WAP). The third block was the control with zero inoculation and zero fertilizer application. Data collected were subjected to an analysis of variance and mean and were separated using Duncan's Multiple Range Test (DMRT) at a p &amp;gt; 0.05 level of probability. It was found that FA3 inoculation significantly enhanced the growth traits of the accessions than other strains and N fertilizer application. In both locations and seasons, at 7 weeks after planting (WAP) and 12 WAP, plant height (19.54 and 22.71 cm), number of branches (33.63 and 62.77), number of leaves (116.54 and 209.25), terminal leaf length (5.62 and 6.00 cm), and width (2.09 and 2.56 cm) were recorded. The yield and yield components recorded at harvest were as follows: pod length (13.27 cm), pod width (9.08 mm), seed length (9.39 mm), seed width (6.92 mm), weight of 100 seeds (56.85 g), and yield/ha (750.72 kg). The yield and yield components were also significantly influenced by the inoculation of FA3 and RACA6 than other inoculated strains and N fertilizer application in both locations and seasons.

Genetic variability, heritability and association among yield components and proximate composition of neglected and underutilized Bambara groundnut [Vigna subterranea (L) Verdc] accessions for varietal development in Ghana

Bambara groundnut is an underutilized crop in Ghana with a lot of potential that can be harnessed to contribute to food and nutritional security in Ghana and Sub-Saharan African countries. The recent experiment was conducted to assess the genetic variability, heritability, and association among the yield components and the proximate composition of the Bambara groundnuts. Twenty-five (25) accessions of Bambara groundnut were sourced from different agro-ecological zones. The results from the analysis of variance showed a highly significant difference (p < 0.001) among almost all the traits studied. The estimate of the broad-sense heritability ranged from 12.50% to 84.458% for seed width and economic yield respectively. High heritability values accompanied by high GA were recorded for hundred seed weight (g), economic yield (g), biological yield (g), harvest index, and yield (kg). The separation of correlation coefficients into direct and indirect effects of component traits for yield traits revealed that traits such as economic yield and pod weight which were positively correlated with yield and exerted a high positive direct effect on yield could be selected for varietal development of Bambara groundnut in Ghana. The results from the proximate composition suggest that the Bambara groundnut accessions used in this study have high nutritional potentials that could serve in the alleviation of food security and nutritional problems when these accessions are selected for varietal development.

Unveiling Genetic Diversity, Characterization, and Selection of Bambara Groundnut (Vigna subterranea L. Verdc) Genotypes Reflecting Yield and Yield Components in Tropical Malaysia.

Addressing genetic diversity and application of appropriate breeding strategies are imperative for Bambara groundnut (Vigna subterranea L.) improvement as a newly introduced legume in Malaysia. It has become a “miracle lucrative” legume for Asia and Africa because of its drought resilience, excellent nutritional profiles, and versatile uses. This crop's progress has been limited owing to a lack of extensive research, marginalization, inadequate knowledge, and a lack of accessible funds, among other concerns. The expansion of this crop is reliant on the assessment and selection of unique and reliable breeding lines in various circumstances. Consequently, the goal of this work is to determine genetic diversity and the relationship between yield-contributing components in 44 Bambara groundnut accessions sourced from the Genebank of Institute of Tropical Agriculture and Food Security (ITAFoS) at Universiti Putra Malaysia (UPM). Three replications were used in the experiment, which was done using a randomized complete block design (RCBD). The data were subjected to ANOVA, PCA, correlation, and heat map cluster analysis; also, genetic parameters and broad-sense heritability estimation were carried out on recorded phenotypic descriptors. All of the investigated variables had a significant variance (p ≤ 0.05 or 0.01) according to the ANOVA results. Yield per hectare showed a positively strong to perfect significant correlation (0.75 ≤ r ≤ 1.00; p ≤ 0.01) with the yield components viz. fresh pod weight, hundred seed weight, dry pod weight, and dry seed weight. Interestingly, these traits had heritability ≥ 60% and genetic gain ≥ 20%, which can be beneficial for direct selection to this crop improvement. The UPGMA clustering revealed five distinct clusters in which genotypes under cluster I, cluster II, and cluster IV produce a greater yield of 5.96%, 7.12%, and 15.05%, respectively, than the grand mean yield of 1927.01 kg/ha. The PCA biplot estimated that PC1 (32.9%) and PC2 (12.9%) would cover 45.8% of the total variance. We discovered 30 promising lines that provide yields per hectare more than 1.8 ton/ha and might be used as parental lines in future breeding operations aimed at improving the grain yield in tropical areas or comparable agroecological zones.

Host status of Bambara groundnut accessions to Meloidogyne incognita using conventional screenhouse and novel seedling pouch methods

Summary Bambara groundnut (Vigna subterranea) is an underexploited legume indigenous to sub-Saharan Africa with high protein content. Production constraints of Bambara groundnut include the root-knot nematodes (Meloidogyne spp.), which causes substantial losses that present an additional burden that growers need to manage. In this study we: i) assessed genetic resistance against Meloidogyne incognita in Bambara groundnut; and ii) evaluated an improved, more efficient screening method for Bambara. Fifty accessions were evaluated in two screenhouse trials. Following this, the use of seedling pouches was assessed for a high throughput screening method, using two accessions identified from each of three host status categories (resistant, tolerant and susceptible). Variability in host response was observed between the trials but five accessions demonstrated good resistance to M. incognita. A general reduction in plant growth parameters was observed on inoculated plants, especially for chlorophyll content at 11 weeks after planting. The pouch screening system confirmed the screenhouse pot results but appears to be more sensitive. From a range of inocula no differences in gall index were observed over the 28 days of assessment in pouches but the number of egg masses proved a useful parameter and differed between inoculum levels, with 500 juveniles/eggs determined as the optimum inoculum level. The use of seedling pouches reduced time, space and cost to screen Bambara groundnuts for resistance against M. incognita. Consequently, it is recommended as an efficient, high throughput, rapid screening protocol for Bambara groundnut compared to conventional pot screening methods.

Morphological characterisation of Bambara groundnut (Vigna subterranea (L.) Verdc.) germplasm collections: A basis for crop improvement

Bambara groundnut is one of the underutilised legume crops adapted to Sub-Saharan Africa's harsh, semi-arid tropical regions, providing nutrition and cash income among resource-poor farmers. A field study comprising 25 Bambara groundnut accessions was carried out during the 2018/2019 cropping season at the Crop Science Experimental Field, University of Namibia-Ogongo Campus, to characterise the accessions using qualitative traits. The experimental design used was an alpha lattice with three replications. Based on the visual observation techniques, the results showed morphological variation among the genotypes. The Bambara groundnut germplasm studied showed high phenotypic variations. The germplasm had a high proportion of the bunch-type growth habit (44% accessions), oval leaflet shape (64%), sparse hairiness (56%), and absence of eye pattern colour (70%). Also, cluster analysis grouped the accessions into five super classes. Shanon-Wennier index indicated a significant level of diversity among the Bambara groundnut accessions for most traits studied, with plant growth habits having the highest index of 2.15, followed by for pod colour (1.45) and seed eye pattern colour (1.22). These results may be useful in formulating national Bambara groundnut breeding programs in semi-arid Sub-Saharan African regions. However, molecular analysis is required to determine the genetic variations among the accessions.

Genetic Analysis and Selection Criteria in Bambara Groundnut Accessions Based Yield Performance

The knowledge of genetic variability and breeding techniques is crucial in crop improvement programs. This information is especially important in underutilized crops such as Bambara groundnut, which have limited breeding systems and genetic diversity information. Hence, this study evaluated the genetic variability and established the relationship between the yield and its components in Bambara groundnut based on seed weight using multivariate analysis. A field trial was conducted in a randomized complete block design with three replications on 28 lines. Data were collected on 12 agro-morphological traits, and a statistical analysis was conducted using SAS version 9.4 software, while the variance component, genotypic and phenotypic coefficient variation, heritability, and genetic advance values were estimated. A cluster analysis was performed using NT-SYS software to estimate the genetic relations among the accessions. The results showed significant variability among the accessions based on the yield and yield component characteristics. The evaluated lines were grouped into seven primary clusters based on the assessed traits using the UPGMA dendrogram. Based on the overall results, G5LR1P3, G1LR1P3, G4LR1P1, G2SR1P1 and G3SR1P4 performed the best for the yield and yield components. These improved lines are recommended for large-scale evaluation and utilization in future breeding programs to develop high-yield Bambara groundnut varieties.

Intraspecific diversity of Vigna subterranea accessions obtained from multinational sources

Bambara groundnut is a legume with balanced meal. The present study investigated agro-morphological diversity of 61 Bambara groundnut accessions whose passport data were from 21 countries. The Genetic Resources Centre (GRC), International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria provided the 61 accessions. The accessions were established in row plots of ten plants on the field at the Centre for Ecological studies, University of Port Harcourt, Nigeria. Seventeen quantitative and two qualitative traits were recorded from the sampling units for each accession. Descriptive and multivariate statistical analysis were employed on the 61 x 19 matrix mean data. Significant variation exists among the 61 accessions for the 19 descriptors. Mean genetic similarity among the 61 accessions was 0.78, the least (0.48) similarity was between TVSu1750 and TVSu250 and the highest (0.92) was between TVSu391 and TVSu415. TVSu1843 flowered earliest at 35 days. The 61 accessions were grouped into three main clusters. TVSu1964 and two accessions from Malawi (TVSu1748 and TVSu1750) in cluster III had high grain yield. Accessions in cluster II were significant for both vigour and grain yield. Striking uniformity and diversity existed among accessions from the same country. Genetic improvement in vigour and grain yield of Bambara groundnut is possible within each country.