Assessment of Agro-Morphological Traits Diversity in Local Cowpea Accessions

All breeding programs and the development of new superior cultivars around the world are based on germplasm genetic diversity. In order to identify the phenotypic diversity and the morphological and agronomical traits relationship among 57 cowpea accessions,  the study was implemented in the field of the National Plant Gene Bank of Iran,in the 2019-20 growing season, The most important phenological, morphological and agronomic traits were recorded. Analysis of variance showed the existence of genetic diversity between the understudied accessions in terms of all quantitative traits except the number of pods per peduncle. The emphasis that it is possible to find out the desired trait among these accessions. Biomass, number of pods per plant, number of seeds per pod, pod length and 100-seed weight had the highest coefficient of variation. The range of phenological traits of day to 50% flowering (43-103) and day to maturity (69-177) showed that these accessions could be categorized as early, medium and late- maturing biotypes. Grain yield and harvest index had a significant negative correlation (P <0.01) with phenological traits. The 100-seed weight and pod length (P <0.01) were determined as traits affecting grain yield. The results of the principal component analysis showed that the three components explain seventy-two percent of the variability between the accessions. Plant height, number and weight of pods per plant, seed number in pod and grain weight per plant had the highest coefficients in the first component and day to flowering, day to maturity and grain yield had the highest coefficients in the second component. A bi-plot drawing of components and grouping genotypes based on  the traits showed that seventeen accessions are noticeable from yield component point of view. Also, seventeen accessions categorized as early-mature accesssins with high grain yield These results in one hand provide useful information about the agronomical traits diversity among local cowpea landraces and on another hand enable the selection of promising genetic resources for use in future breeding programs.