Bambara Groundnut Landraces Research Articles

Assessment of Genetic Diversity in Bambara Groundnut (Vigna subterranea) Landraces Based on Seed Storage Proteins Electrophoretic Pattern

Bambara groundnut (Vigna subterranea) is a leguminous crop that is considered underutilized and has previously received little research attention. Variability in a number of physiological factors, including germination rate, widely affects its production. Seed storage protein, its fractions and protein profile of six Bambara groundnut local landraces were studied to assess their genetic relatedness. Total seed storage protein and its fractions were estimated by Bradford’s method. SDS-PAGE analysis was used to evaluate storage protein profile. The results showed significant differences (p<0.05) in protein contents among the landraces. The major seed storage proteins were found to be globulins (0.048 to 0.088mg/mL ), albumins (0.023 to 0.038mg/mL ), glutelins (0.007 to 0.013mg/mL ) and prolamins (0.002 to 0.004mg/mL ). Five peptide bands were detected with molecular weights corresponding to 97.4 kDa, 45 kDa, 29 kDa, 20.1 kDa and 18 kDa, respectively. Three peptide bands corresponding to 97.4 kDa, 45 kDa and 18 kDa were detected in all the landraces and two peptide bands between 29 kDa and 20.1 kDa were detected in five landraces. Dendrogram generated by UPGMA grouped the six landraces into one major cluster with two sub-clusters. The observed diversity in storage protein pattern of the landraces indicated their potential as materials for crop improvement.

Genetic diversity and population structure analysis of bambara groundnut (Vigna subterrenea L) landraces using DArT SNP markers.

Understanding the genetic structure and diversity of crops facilitates progress in plant breeding. A collection of 270 bambara groundnut (Vigna subterrenea L) landraces sourced from different geographical regions (Nigeria/Cameroon, West, Central, Southern and East Africa) and unknown origin (sourced from United Kingdom) was used to assess genetic diversity, relationship and population structure using DArT SNP markers. The major allele frequency ranged from 0.57 for unknown origin to 0.91 for West Africa region. The total gene diversity (0.482) and Shannon diversity index (0.787) was higher in West African accessions. The genetic distance between pairs of regions varied from 0.002 to 0.028 with higher similarity between Nigeria/Cameroon-West Africa accessions and East-Southern Africa accessions. The analysis of molecular variance (AMOVA) revealed 89% of genetic variation within population, 8% among regions and 3% among population. The genetic relatedness among the collections was evaluated using neighbor joining tree analysis, which grouped all the geographic regions into three major clusters. Three major subgroups of bambara groundnut were identified using the ADMIXTURE model program and confirmed by discriminant analysis of principal components (DAPC). These subgroups were West Africa, Nigeria/Cameroon and unknown origin that gave rise to sub-population one, and Central Africa was sub-population two, while Southern and East Africa were sub-population three. In general, the results of all the different analytical methods used in this study confirmed the existence of high level of diversity among the germplasm used in this study that might be utilized for future genetic improvement of bambara groundnut. The finding also provides new insight on the population structure of African bambara groundnut germplasm which will help in conservation strategy and management of the crop.

Assessment of genetic diversity and structure of Bambara groundnut [Vigna subterranea (L.) verdc.] landraces in South Africa

With its drought tolerant and protein-rich properties, Bambara groundnut [Vigna subterranea (L.) Verdc.], an indigenous African legume crop can contribute immensely to food security. This miracle crop is used as food and for the enhancement of soil fertility in South Africa. Knowledge on the genetic diversity and structure among the Bambara groundnut landraces can pave the way for the effective use and cultivation of this crop in southern Africa, especially South Africa. The aim of this study was to assess the genetic diversity and structure among Bambara groundnut landraces collected across South Africa and compared to a limited number of accessions from southern Africa using SSR markers. Seventy-eight Bambara groundnut accessions were genotyped using 19 Bambara specific SSR markers. SSR loci explored in this study, were all polymorphic. A total of 127 alleles were detected with a mean of 6.7 alleles per locus. Allele diversity and frequency among genotypes varied from 0.21 to 0.85 with an average of 0.62 per locus. Genetic variation as described by the analysis of molecular variance indicated higher genetic diversity (92%) within landraces than between (8%) different landraces. Population structure analysis showed that three subpopulations existed, and most of the South African accessions were restricted to one subpopulation, indicating that Bambara landraces has the ability to form unique haplotypes in different environments. Information harnessed in this study is helpful for further use in breeding programs for crop improvement.

Spectrophotometric Quantification of Phytic Acid During Embryogenesis in Bambara groundnut (Vigna subterranea L.) Through Phosphomolybdenum Complex Formation

In relation to seed vigour and hyperosmotic stress, phytic acid has implications in imparting drought tolerance and enrichment of seed mineral reserves respectively. The present study was undertaken to determine the variation in phytic acid during seed development and physiological maturity of 4 Bambara groundnut landraces. The landraces were grown in field during 2017–2018 rain season at Ukulinga, Pietermaritzburg. The phytate content was estimated indirectly from 14-65 days after flowering (DAF) by using a spectrophotometer, evaluating the total extractable phosphorus absorbance at 720 nm. An analysis is described for the rapid determination of phosphorus in developing seeds. The colour complex (phosphomolybdenum) formed under acidic conditions absorbs maximally at 720 nm in acidic (pH<4.5) solutions. Absorbance of the chromophore when measured spectrophotometrically at 720 nm, it obeys Beer’s law over the range of 0 to 75 ppm of standard phosphorus solution. There were significant differences (P<0.001) in total extractable phosphorus at 14, 21, 28, 35, 42 and 65 DAF. The highest and lowest extractable phosphorus was recorded in G340A and Kazai respectively. Pi seed content was between 1.51 and 5.69 mgkg-1 at 14 DAF, at physiological maturity (65 DAF) Pi was recorded between 21.73 and 32.23 mgkg-1. We drew conclusions that Bambara groundnut landraces may differ in both (1) phytic acid accumulation rate and (2) phytic acid content at physiological maturity. The results reported open the possibility of a specific seed selection criterion for improving the mineral element value of Bambara groundnut through the identification of landraces with high-Pi (phytic acid).

Genetic Variability, Heritability, and Clustering Pattern Exploration of Bambara Groundnut (Vigna subterranea L. Verdc) Accessions for the Perfection of Yield and Yield-Related Traits.

Bambara groundnut (Vigna subterranea L. Verdc.) is considered an emerging crop for the future and known as a crop for the new millennium. The core intention of this research work was to estimate the variation of landraces of Bambara groundnut considering their 14 qualitative and 27 numerical traits, to discover the best genotype fitted in Malaysia. The findings of the ANOVA observed a highly significant variation (p ≤ 0.01) for all the traits evaluated. There was a substantial variation (7.27 to 41.21%) coefficient value, and 14 out of the 27 numerical traits noted coefficient of variation (CV) ≥ 20%. Yield (kg/ha) disclosed positively strong to perfect high significant correlation (r = 0.75 to 1.00; p ≤ 0.001) with traits like fresh pod weight, dry pod weight, and dry seed weight. The topmost PCV and GCV values were estimated for biomass dry (41.09%) and fresh (40.53%) weight with high heritability (Hb) and genetic advance (GA) Hb = 95.19%, GA = 80.57% and Hb = 98.52%, GA = 82.86%, respectively. The topmost heritability was recorded for fresh pod weight (99.89%) followed by yield (99.75%) with genetic advance 67.95% and 62.03%, respectively. The traits with Hb ≥ 60% and GA ≥ 20% suggested the least influenced by the environment as well as governed by the additive genes and direct selection for improvement of such traits can be beneficial. To estimate the genetic variability among accessions, the valuation of variance components, coefficients of variation, heritability, and genetic advance were calculated. To authenticate the genetic inequality, an unweighted pair group produced with arithmetic mean (UPGMA) and principal component analysis was executed based on their measurable traits that could be a steadfast method for judging the degree of diversity. Based on the UPGMA cluster analysis, constructed five distinct clusters and 44 accessions from clusters II and IV consider an elite type of genotypes that produce more than one ton yield per hectare land with desirable traits. This study exposed an extensive disparity among the landraces and the evidence on genetic relatives will be imperative in using the existing germplasm for Bambara groundnut varietal improvement. Moreover, this finding will be beneficial for breeders to choose the desirable numerical traits of V. subterranea in their future breeding program.

Genetic variability of Indonesian landraces of Vigna subterranea: Morphological characteristics and molecular analysis using SSR markers

Abstract. Alhamdi MFF, Setiawan A, Ilyas S, Ho WK. 2020. Genetic variability of Indonesian landraces of Vigna subterranea: The morphological characteristics and molecular analysis using SSR markers. Biodiversitas 21: 3929-3937. Bambara groundnut (Vigna subterranea (L.) Verdc.) is a potential grain, which can be considered as an alternative source of protein and carbohydrate. Due to unavailability of commercial bambara groundut cultivar in Indonesia, the characterization of bambara groundnut landraces is an important step before developing cultivar with traits of interest. The objective of the research was to access genetic variability of Indonesian landraces of bambara groundnut with different seed coat colors based on morphological and molecular markers. The experiment was arranged as split-plot in a complete randomized block design with the main plot was cultivation methods and the sub plot was landraces. There were differences in leaf shape and pod shape among the landraces. There were two main clusters of Indonesian landraces of bambara groundnut with 88.28% similarity. The first cluster was Cream, Brown Sumedang, Black Sumedang and Black Tasikmalaya, and the second cluster was Black Sukabumi, Brown Gresik, Black Madura, and Black Gresik. The result based on SSR marker with capillary electrophoresis indicated Black Gresik and Black Madura landraces were different from other Indonesian landraces. Cream Sumedang or Brown Sumedang from the first cluster and Black Gresik or Brown Gresik from the second cluster have the farthest distances for developing improved variety of bambara groundnut.

Understanding the genetic relationships between Indonesian bambara groundnut landraces and investigating their origins.

A total of 170 bambara groundnut (Vigna subterranea) accessions were evaluated using both simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers generated using genotyping-by-sequencing (GbS), of which 56 accessions were collected from West and East Java. Principal coordinate analysis (PCoA), population structure, and cluster analysis suggest that the East Java accessions could be a result of the introduction of selected West Java accessions. In addition, the current Indonesian accessions were likely introduced from Southern Africa, which would have produced a very marked founding effect such that these accessions present only a fraction of the genetic variability that exists within this species.

Assessment of bambara groundnut landraces for resistance to <i>Cowpea aphid borne mosaic virus</i>

Bambara groundnut ( Vigna subterranea ) is an important seed legume in Burkina Faso. It provides a well-balanced diet and many other benefits for populations, especially in rural areas. Despite all these advantages, bambara groundnut cultivation remains subject to many constraints. One of the most important of them is viral diseases. This study was conducted in order to identify from Burkina Faso bambara groundnut landraces, some resistant genotypes to Cowpea aphid-borne mosaic virus (CABMV). In this study, 20 bambara groundnut landraces collected from three climatic zone of Burkina Faso were tested. According to their level of sensitivity to the CABMV isolate tested we obtained two groups of genotypes: G1 and G2. After retroinoculation, only six landraces, namely E119, E117, E105-a from Sahelian zone and E53-a, E103 and E97 from Sudan-sahelian zone, showed a resistance to the CABMV isolate. These results could be used to develop control strategies against viral diseases. Keywords: Vigna subterranea , Burkina Faso, CABMV, viral diseases, susceptibility

Evaluation of Soybean varieties and Bambara Groundnut landraces for agronomic characters when cultivated on different soils of Lake Victoria Basin

Evaluation of Soybean varieties and Bambara Groundnut landraces for agronomic characters when cultivated on different soils of Lake Victoria Basin

Full title- In vitro digestibility, amino acid profile and antioxidant activity of cooked Bambara groundnut grain

The effect of wet cooking on the nutritional and functional properties of two Bambara groundnut landraces and a reference dry bean was studied. Wet cooking increased the amino acid concentration of the Bambara landraces for most of the amino acids tested, but the methionine content of the two Bambara landraces and the reference bean decreased by approximately 90, 90 and 20%, respectively. Carbohydrate and fiber contents of all the samples increased after cooking. Cooking led to a significant increase in the total phenolic content of the grains and decreases in phytic acid and tannin contents, which seems to have resulted in an increase in the in vitro starch and protein digestibility of all the samples. Thermal processing had varying effects on the conformation of proteins as observed in the FTIR spectra of each sample. However, nutrients were well retained and antinutrients reduced significantly.

Seed mineral reserves and vigour of Bambara groundnut (Vigna subterranea L.) landraces differing in seed coat colour

A newly emerged seedling, given light and water, but no external source of minerals, uses its internal mineral nutrient reserves effectively for an early establishment. This research sought to investigate the influence of seed coat colour on the abundance of mineral elements in Bambara groundnut. Four landraces (G340A, Kazai, Kazuma, and Mana) varying in seed coat colour were analysed for differences in seed mineral composition using energy dispersive x-ray (EDX) analysis and atomic absorption spectrometry (AAS). Seeds were germinated at 10 °C and 25 °C, and various indices including, (1) mean emergence time, (2) mean germination rate, (3) coefficient of velocity of germination, and (4) final germination percentage (FGP) were calculated. The importance of seed mineral elements in the establishment of Bambara groundnut was examined by measuring root length (RL), shoot length (SL), shoot dry mass (SDM), and root dry mass (RDM). Plant tissue elemental analysis was done using flame atomic emission spectrometry (FAES) for K and flame atomic absorption spectrometry (FAAS) for Mg, Cu, Mn, and Zn. There were significant differences (P < 0.001) in mineral element content of dry seeds. G340A and Kazai had the highest and the lowest K, P, Mg, Mn, and Zn (11.65 gkg-1, 7.2 gkg-1, 2.33 gkg-1, 59.56 mgkg-1, and 44.42 mgkg-1), and (8.82 gkg-1, 4.75 gkg-1, 1.38 gkg-1, 48.9 mgkg-1, and 42.6 mgkg-1), respectively. Cold test germination indices were significantly different, the highest FGP was 73.3% in G340A and the lowest was 57.8% in Kazai. There were strong positive correlations between seed mineral concentration and plant growth parameters (p < 0.001). We concluded that (1) seed mineral concentration has a significant impact on the early establishment of Bambara groundnut and (2) the dark-coloured landraces (hue 8º) used in this study have the highest concentration of macro and micro elements compared to light coloured seeds (hue 38º).

Seed coat structural and imbibitional characteristics of dark and light coloured Bambara groundnut (Vigna subterranea L.) landraces

Bambara groundnut is cultivated using landraces of different seed coat colours. However, very few studies have associated the seed coat colour (morphological feature) with other physiological and biochemical processes as underlying the observed differences in seed quality among landraces. This research sought to investigate seed quality characteristics (viability and vigour) of landraces on the basis of seed coat colour with the hypothesis that; seed coat colour could be linked to other properties (physical, physiological, biochemical and ultra-structure) that may account for seed quality with respect to germination, vigour and storage potential. Four landraces were analysed for differences in seed coat colour and seed coat thickness using a scanning electron microscope (SEM). Seed imbibition, electrolyte conductivity, tetrazolium test, and standard germination tests were combined to evaluate the viability of seeds after deterioration through accelerated ageing (AA) at 42 °C and 100% relative humidity (RH) over 5 durations, namely 24, 48, 72, 96 and 120 hours. There were significant differences (P < 0.001) among landraces with respect to seed coat colour, seed coat thickness, electrical conductivity (EC), hydration rate, germination rate and length of the measured seedling axis. The light coloured landrace, Kazai, had the highest germination (66.9%) whereas the dark coloured landrace, G340A, had the lowest final germination (53.6%) after 120 hours of seed ageing. Likewise, G340A and Kazai had the highest (110.33 μS cm-1 g−1) and lowest EC (92 μS cm-1 g−1), respectively. Electron microscope revealed that dark and light seeds had the thickest (127 μm) and the thinnest (104.6 μm) seed coats, repsectively. This study highlighted that (1) seed coat thickness and colour alone do not account for hydration pattern of Bambara groundnut landraces and (2) Bambara groundnut seeds viability may not necessarily imply good seed vigour.

SEED DETERIORATION PATTERN OF FOUR BAMBARA GROUNDNUT LANDRACES (Vigna subterraneasubterranean (L) Verdc) IN OPEN STORAGE SYSTEM

Bambara groundnut (Vigna subterranea (L.) Verdc) is a potential commodity to be developed in Indonesia, however, the production is done only once a year, therefore, it needs proper seed storage. The aim of this research was to study seed deterioration patterns of four bambara groundnut landraces stored in packages with different permeability in an open storage system for up to 6 months. This experiment was conducted from November 2015 to July 2016 at Seed Technology Laboratory, Department of Agronomy and Horticulture, IPB. Stages of experiment as follow: calculation of packaging permeability, seed storage, preparation and fitting data to regression equation.The packaging used in the study is aluminum foil, pp plastic and plastic sacks which have measured its permeability. The result showed that the seed deterioration of four bambara groundnut landraces in three packaging permeability has common sigmoidpattern with equation model: y = a / {1 + exp ((x + b) / c)}. The seed deterioration pattern based on SG and EC variables with the faster rate of decline occurred in Sumedang landrace packed in plastic sack (permeability = 1.4681 g/day m2 mm/Hg), thus having a shorter storability. The slower rate of decline occurred in Gresik landrace packed in aluminum foil (permeability = 0.098 g/day m2 mm/Hg), this means that it has a longer storability.

Evaluation of Seed Yield of Nigerian Bambara Groundnut [Vigna subterranea (L.) Verdc.] Landraces under Varying Water Conditions

Seed yield of selected Nigerian Bambara Groundnut landraces under two varying water conditions was evaluated. Twenty eight (28) Bambara groundnut accessions were planted in a randomized complete block design with two treatments (Non-water stressed and Water stressed) and replicated five times. The experiment was conducted at the Experimental Garden of the Department of Biological Sciences, Federal University of Technology, Minna, Niger State. The accessions were planted in planting bags during the cropping season of 2016 between July and October. The two treatments were rain fed until maturity except during the period of exposure to water stress where the water stressed plants were transferred to a screen house made with polyvinyl ceiling to prevent water during the flowering stage for two weeks. It was observed that water stress reduced the yield of the Bambara groundnut landraces by 47%. Accessions NGB-01646-B, NGR-NI-20-H and NGB-01491 which had relatively high yield in the stressed and non- water stressed condition were considered the most drought tolerant accessions and accession NGR-KG-02-C with low yield both in stressed and non-stressed conditions was identified as the most susceptible accession. Accessions which had high yield only in water stressed conditions could serve as elite line for Bambara groundnut for areas which have problem of drought. These drought tolerant accessions identified in the research can serve as potential parent lines in breeding programmes aimed at the development of drought tolerant varieties of Bambara groundnut.

Phytochemical profile of seeds from 21 Bambara groundnut landraces via UPLC-qTOF-MS

Bambara groundnut is one of the under-utilized African legume crops, valued for its nutritional and health benefits, and for which ongoing studies will help to distinguish its many landraces and select the promising one for breeding programs. To describe the polar metabolome of the seed from 21 Bambara groundnut landraces, untargeted metabolomics approach using UPLC-qTOF-MS (Ultra performance liquid chromatography-Quadrupole time of flight mass spectrometry) was performed. Metabolites belonging to varied compound classes were detected and identified. The total phenolic, flavonoid and anthocyanin contents varied from 0.75 to 17.71 mg GAE.g−1, 0.01 to 2.51 mg QUE.g−1 and 0.03 to 1.31 mg CYE.g−1, respectively. Unsupervised statistics highlighted differences in the metabolome of different landraces. Principal component analysis revealed that caffeic and catechin conjugates are the most decisive marker compounds discriminating the landraces. This study provides the most complete map of metabolites in Bambara groundnut seeds and demonstrates that UPLC-qTOF-MS coupled with chemometric is an excellent tool for differentiation between landraces. These findings highlight the potential of Bambara groundnuts as an economic source of natural antioxidants for human consumption and food industries, and therefore open horizons to the industrial use of Bambara groundnut flours in the development of functional food and feed products.

Drought affects protein and phenolic content in bambara groundnut (&lt;i&gt;Vigna subterranea&lt;/i&gt; L. Verdc.)

Bambara groundnut ( Vigna subterranea L. Verdc.) is a legume crop, which has long been recognised as a protein-rich and drought-tolerant crop, used extensively in sub-Saharan Africa. This study evaluates the effect of experimental water deficit stress on total protein concentration, secondary protein structure and the total phenolics content on three Bambara groundnut landraces. Plants were grown in pots in a screen house. Water deficit was induced at the vegetative stage by withholding irrigation while fully watered plants served as control. Predominantly, β-sheet structure was observed in all the stressed as well as the control plants even though differences were observed between the treatments. Water deficit stress led to significant (P<0.05) increase in total protein content, but total phenolics content in all the landraces increased slightly. Drought stress induced significant increase in the synthesis of various proteins as part of the response strategy. The slight increase in total phenolics in the leaves of drought-stressed plants might be related to the antioxidant defence role of the phenolics. Correlation analysis of the total protein and phenolics indicated a strong positive relation across the three landraces studied. The results of the present work points to the resilience of the Bambara groundnut species to water deficit. Keywords: Bambara groundnut, water-deficit, protein content, phenolics, FTIR spectroscopy

Agromorphological diversity of local Bambara groundnut (Vigna subterranea (L.) Verdc.) collected in Benin

Bambara groundnut (Vigna subterranea (L.) Verdc.) is a neglected and less exploited species in Benin. However, the rational use of the different landraces available involves an appropriate knowledge of their characteristics. This study examined the characteristics of 52 local landraces of Bambara groundnut traditionally cultivated in Benin based on 12 qualitative and 11 quantitative variables, in order to expose those of good qualities. After a classification based on the morphological variables of the seeds, the experimental field was installed in a completely randomized device of blocks repeated three times. The collected data was analyzed with Statistica 7.1 and NTSYS PC 2.2. softwares using qualitative characteristics (Growth’s type, Stem’s hairiness, Flower’s colour, Leave’s shape etc.). As result, the number of morphotypes increased from 18 (out of classification) to 47. Therefore, it appears that the Benin collection of Bambara groundnut is broad in morphological variability. The analysis of the principal component of the quantitative variables revealed three specific classes within the collection. The most efficient variety which belonged to the second class, had a high field yield per hectare (> 1 t/ha). The Souhouloumankpa variety yielded the earliest (103 days after sowing) in addition to the high field yield. The study also showed a positive relationship between 100 seed’s weight, their length, the number of seeds per plant and the seed’s field yield in kg/ha. For a sustainable preservation and an improvement of the available resources, a molecular characterization of the Bambara groundnut landraces in Benin Republic needs to be done.

Keragaman Genetik dan Kekerabatan Genotip Kacang Bambara (Vigna subteranea L.) Lokal Jawa Barat

Bambara groundnut (Vigna subteranea L.) is one of underutliized crops in Indonesia. Bambara groundnut is potential to be developed and can be utilized as an alternative food source in Indonesia. Bambara groundnut greatly varies and has a very wide area of adaptation. The experiment was conducted at the experimental field station at Ciparanje in Padjadjaran University. Starting on September 2014 until March 2015 with Randomized Block Design (RBD) and repeated two times. The research used 30 accessions originally from various locations in West Java (Bandung, Tasikmalaya, Garut, Sumedang, Bogor, Majalengka) and East Java (Lamongan, Madura). Genetic variability of Bambara groundnut landrace in some West Java showed broad criteria on the characters fresh pod weight, dry pod weight, weight of 100 seeds, and weight per plot. Genotypes which had many similarities in some characters based on euclidian distance coefficient had close relationship.

Anti-nutrient analysis of 30 Bambara groundnut (Vigna subterranea) accessions in South Africa

ABSTRACTBambara groundnut is a leguminous crop that originated in West Africa. It is a drought-tolerant crop and has the potential to provide improved food and nutritional security in the dry areas of Africa. However, the plant contains anti-nutritional factors that affect its food value chain. The objective of this study was to assess the content of four major anti-nutritional factors in 30 bambara groundnut accessions in South Africa. The seeds of the bambara groundnut landraces were ground to make a fine powder and assessed for condensed tannins (CTs), phytic acid phosphate (PAP), polyphenol, and trypsin inhibitor content. Each assay was done in triplicate. The content of the four anti-nutritional compounds varied widely among the bambara groundnut accessions. The mean values for CTs ranged between 0.2 and 6.2 mg/g of prodephinidin equivalent, whereas that of the PAP was between 1.4 and 4.9 mg/g. A low mean polyphenol content of 0.4 mg/g of GA (gallic acid) equivalent was observed among the accessions. The level of trypsin inhibitor ranged from 5.3 to 73.4 TI/mg. With the exception of CTs and trypsin inhibitor, no significant correlation was observed among the four anti-nutritional factors assessed in this study. Generally, higher levels of anti-nutrients were observed in this study compared with certain studies reported earlier.

Modelling Pod Growth Rate of Bambara Groundnut (Vigna subterraneaVerdc.) in Response to Photoperiod and Temperature

Photoperiod and temperature are important environmental factors that affect the adaptation of bambara groundnut (Vigna subterraneaVerdc.) and other crops to hostile climates in the tropics. The use of the accumulation concept, in which the relative rate of progress towards podding sums up to one is a common methodology. However, the lack of quantitative information, has resulted in poor decision making for crop management practices in relation to the time of optimum pod growth rate (Ropt). This study investigated modeling pod growth using an additive and interactive relation between pod growth rate, mean photoperiod, and temperature during the pod inductive phase. The field experiment was conducted at Ekpoma Nigeria. Ten bambara groundnut landraces from three different regions in Nigeria (Anyigba, Otukpo, and Nsukka) were sown on six dates from 15 June to 1 September during the successive growing seasons of 2010 to 2012, thus exposing the landraces to mean natural photoperiods of 12 h 23 min, 12 h 19 min, 12 h 14 min, 12 h 10 min, 12 h 5 min, 12 h, 11 h 55 min, 11 h 51 min, and 11 h 47 min during the pod inductive period. The observed optimum photoperiod and temperature forRoptwere 12 h and 26°C, respectively, for all landraces. Allocation to pod growth began at the critical photoperiod (Pc) of 12 h 19 min for Otukpo landraces, whereasPcfor Nsukka landraces was 12 h 14 min. However, thePcfor Anyigba landraces occurred earlier at 12 h 23 min. The pod growth model that was developed provided good predictions of pod growth for a natural range of photoperiods and temperatures.