Influence of seed and pod biophysical characters on pre-harvest sprouting tolerance in urdbean ( Vigna mungo L.)

Pre-harvest sprouting (PHS) is an environmentally induced phenomenon, which causes severe yield losses in urdbean under humid weather conditions. Concerning PHS, deployment of genotypic capacity for PHS tolerance would be a feasible approach, but has not been evaluated in urdbean. Therefore, a laboratory-based study was conducted to investigate the genotypic potential of PHS tolerance in urdbean and to understand the influence of various seed and pod physical and physiological traits on PHS. A panel of 140 diverse urdbean genotypes was tested for seed and pod morphological attributes, water imbibitions patterns, fresh seed germination, germination time, and physical dormancy or hard seededness for characterizing the trait PHS. A wider variation in PHS (3–94%) was observed within the genotypes and the trait hard seededness was found as the key determinant of PHS tolerance in urdbean. The genotypes with lower PHS (< 10%) had a mean hard seededness of 77%, while, the genotypes with higher PHS (> 70%) recorded a mean hard seededness of 7%. Results further demonstrated that the persistence of hard seededness is highly genotype specific and temporal in character, which was highest in the freshly harvested seeds and decline over the storage period. The correlation results indicated that seed weight, seed length, pod water imbibitions, seed water imbibitions, mean germination time, and fresh seed germination positively influenced PHS. The large-seeded genotypes (> 4 g 100 seeds −1 ) showed higher PHS than the small-seeded genotypes (< 3 g 100 seeds −1 ). The multivariate analysis results further confirmed the positive relationship of PHS with pod water imbibitions, fresh seed germination, and 100-seed weight. The PHS tolerant genotypes PLU 302, CN 35–15, and PLU 65, which recorded hard seededness of 70–88% after harvesting, and reduced to < 24% after 60 days could be used as potential donors for the improvement of urdbean.