Morphometric analysis and characterization of the nutritional quality in African yam bean accessions

Underutilized crops with rich nutritional base in addition to high seed yield are currently promoted in reducing hunger and malnutrition ravaging Africans. Identifying specific accessions with rich genetic bases provide information for developing biofortified legumes. Fourteen morphological and two nutritional traits of 23 African yam bean accessions were assessed under a replicated field trial in one location over 4 years. Analysis of variance revealed significant variations for most traits with high genotypic correlation coefficients. Genotypic coefficient of variation was high for maturity date (59.95%), protein content (60.78%), tuber yield per plant (67.33%) and number of seeds per pod (77.22%). Seed yield did not correlate with protein and oil content, indicating that nutritional traits were independent of seed yield traits. Heritability was high for most traits but moderate for protein and oil content. First order predictor variables, identified number of seeds per pod, and pod traits to directly affect seed and tuber yield. First seven principal components axes explained 67% of total variation including nutritional traits. Four distinct accession clusters at the R-squared distance of 0.45 similarity index were identified. Simultaneous improvement in earliness, yield, protein and oil contents are achievable by selecting parents from clusters I and II. The only accession in cluster III (TSs12) produced nodules in addition to average seed yield, protein and oil content, and could be selected for cultivation in nitrogen deficient soils. Wide diversity in these accessions can be maximized for developing acceptable African yam bean varieties with enhanced yield and nutritional value