Characterisation of 4274 accessions of common bean (Phaseolus vulgaris L.) germplasm conserved in the Indian gene bank for phenological, morphological and agricultural traits

Common bean is one of the most important legume crops worldwide. Response to selection and success of hybridisation in common bean primarily depends on the nature and magnitude of genetic diversity present in the germplasm used. Germplasm comprising 4274 accessions originating from 58 countries were characterized for 22 phenotypic traits for two years. Genetic diversity for traits such as leaf length (4.5-20.7 cm), leaf width (3.4-17.5 cm), pod length (PL) (3.5-23.5 cm), no of pods/plant (4.2-59.6), seeds/pod (2.1-9.6) and 100-seed weight (SWT) (3.5-96.3 g) was observed in the accessions. Based on multivariate analysis, the entire collection was grouped into 10 genetically diverse clusters irrespective of the origin or place of collection of accessions. First three components obtained through principal component analysis explained 80.44 % of the total variance and it was contributed mainly by PL, pod width (PW), seed length (SL), seed width (SW), pods/plant and SWT. Correlation coefficient of seed weight was positively significant with leaf length, PL, PW, SL and SW while it was negatively correlated with days to flowering, pods/plant and seeds/pod. Regression analysis showed highest direct effect of SW on seed weight followed by SL, and PL. For bean anthracnose, > 600 accessions showed resistance under field conditions, however when subjected to screening under artificial conditions against four most prevalent races (03, 515, 598 and 529) of Colletotrichum lindemutianum, we identified 16 accessions which have complete resistance and good agronomic superiority. These accessions may serve as useful genetic material to plant breeders for breeding bean varieties for anthracnose resistance and high yield.