Unravelling phenotypic variations and establishing a core collection in mungbean for accelerating the crop improvement programs

Mungbean Vigna radiata (L.) R. Wilczek, is an Indian-origin legume crop and is emerging as an excellent food for human health and nutrition globally. However, the narrow genetic base in its released varieties is a bottleneck in mungbean yield enhancement. Therefore, 3903 accessions of mungbean were characterized to identify trait-specific donors, understand potential traits for breeding purposes, and select a core collection for enhancing germplasm utilization in the mungbean breeding program. A common set of 28 phenotypic traits was used for evaluation at two locations for two years (for 2019 and 2020) in an augmented block design. A substantial amount of phenotypic variation was observed in mungbean collections as revealed by diversity indices, frequency distribution, hierarchical clustering, and principal component analysis. Traits such as plant biomass, days to 50% flowering, days to maturity, plant height, and number of seeds/pod showed higher levels of heritability and genetic gains. The core development strategy involved the development of five independent core sets of 400 accessions based on different statistical methods. Among the five sets, a core collection i.e., EN100 (average entry-to-nearest-entry distance with 100% weightage), was identified as the best among all five core sets based on quality evaluation indices. The chosen core collection was further compared with the entire collection using various statistical parameters. The core collections showed optimum results based on the various quality assessment parameters such as mean difference (MD, 66.67%), variance difference (VD, 100%), coincidence rate of range (CR, 97.4%), variable rate of range (VR, 119.6%), class coverage (100%) and a higher level of coefficient of variation (CV) for all the quantitative traits. These findings provide insights into the mungbean germplasm diversity, which will play a significant role in the mungbean improvement programs. Additionally, the diversity-rich core collection will be a ready resource for breeders and researchers to address various research problems.