Comparative Assessment of Green Gram (Vigna radiata (L). Wilczek) Genotypes of Different Maturity Groups for Tolerance to Terminal Drought Stress (TDS)

Abstract

Background: Direct selection of genotypes for high grain yield under Moisture Stress Free (MSF) environment with minimal reduction in grain yield under Terminal Drought Stress (TDS) environment is considered as the most effective and sustainable strategy to breed crops (including green gram) for drought tolerance. We hypothesize that genotypes of different maturity groups differ with respect to their tolerance to drought stress. Methodology: To test our hypothesis, a total of 231 germplasm accessions, which included 38 extra early, 49 early, 70 medium and 74 long duration genotypes were evaluated in Augmented design for grain yield at two locations (Bidar and Gulbarga) during summer across two years (2021-2022 and 2022-2023) under managed TDS and MSF environments. The per cent reduction in grain yield and four reported indices namely stress tolerance index, arithmetic mean productivity, harmonic mean productivity and geometric mean productivity were estimated based on grain yield of genotypes under TDS relative to MSF environment. The lower magnitudes of estimates of per cent reduction in grain yield and higher magnitudes of four indices were interpreted as greater tolerance to TDS. Results: The results suggest that response of genotypes to TDS differed with the location represented by differences in weather parameters. When weather parameters are favorable (relatively lower day and night temperature and higher RH at Bidar), extra early and long duration genotypes were more tolerant than other two maturity groups. On the other hand, when weather parameters are harsh (relatively higher day and night temperature and lower RH at Gulbarga), long duration genotypes are more tolerant to TDS than other maturity groups.