Variability and heterosis of seed vigour traits in hybrid rice (Oryza sativa L.)

The cultivars with high seed vigor are desirable for farmers to establish optimum plant stand under sub-optimal field conditions. The basic physiological processes are required to understand the hybrid vigor phenomenon, particularly for seed vigor and associated characteristics. Limited information on seed vigor in rice hybrids and their parental lines in relation to physical, physiological and biochemical characters are available. Three released rice hybrids and their respective female (A), maintainer (B) and restorer/male (R) lines were assessed for physical, physiological and biochemical traits related to seed vigor. Significant differences were found among the three rice hybrids and its parental lines for 100 seed weight, weight of kernel, husk, endosperm and embryo. Germination percentage, seed vigor index-I and seed vigor index-II were highly significant among female and male lines and hybrids in fresh seed because of potential heterosis in hybrids. Higher activity of reactive oxygen species (ROS) scavenging enzymes such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in hybrids was estimated as compared to that of their parental lines. The study showed the presence of the genetic variability, phenotypic, genotypic and environmental coefficient of variation, heritability, genetic advance and heterosis for seed vigor traits in three rice hybrids and its parental lines. A favorable combination of seed vigor traits would be useful to develop desired variety and hybrids with superior seed vigour for realizing higher grain yield and better adaptability in any condition.