Heritability of hardseededness in mungbean [Vigna radiata (L.)Wilczek] under varying environments

Presence of hard seeds in seed lots reduces the seedling emergence percentage in field leading to non-uniform, lowered plant population and uneven maturity. Seed hardness, characterized by no water imbibition, is controlled by both genetic and environmental conditions. To estimate the broad sense heritability (H2) of hardseededness, 20 mungbean genotypes with >22% hard seeds were grown in four different environments (Env.) viz., high average temperature and high soil moisture (Env. 1), mild temperature and low soil moisture (Env.2), mild temperature and high soil moisture (Env. 3) and low average temperature and low soil moisture (Env.4). The average per cent hard seed in seed lots was 5.42, 28.7, 19.4 and 33.9 under Env.1, Env.2, Env.3 and Env.4, respectively. The H2 estimate of hardseededness under Env.1, Env.2, Env.3 and Env.4 was 0.67, 0.97, 0.96 and 0.98, respectively. Decreasing soil moisture, low temperature and delayed harvest increased occurrence of per cent hard seed. The force required in Texture Analysis Machine to break seeds produced under Env.1 ranged from 9.23 to 33.31 Newton while the same ranged from 39.51 to 71.53 Newton in seeds produced under Env.4. The Scanning Electron Microscope images indicated that the seeds produced under low average temperature and soil moisture had a presence of compact outer cell layer with low surface deposition and depression on the seed coat of seeds produced in Env.1 and there is existence of loose cells and cracks in the seed coat with high depression and surface deposition in the seeds produced under Env.4. A lower heritability of 0.67 for hardseededness in high temperature and soil moisture condition suggested that the character is influenced by stress conditions. Growing of genotypes under low temperature and moisture condition is suggested for screening of genotypes for hardseededness in mungbean.