Grain γ-oryzanol and its constituent compounds show high genetic variability, diversity and significant site x genotype interactions in rice (Oryza sativa L.)

Among the dietary antioxidants that counteract oxidative stress to avert the incidence of non-communicable diseases (NCDs), γ-oryzanol, a unique antioxidant in rice shows potential health benefits. Although rice germplasm exhibits significant variation for γ-oryzanol content, much less is studied on the influence of environment (E) and genotype-environment interaction (GEI) on the γ-oryzanol content in rice bran. Evaluated under three sites, in a combined analysis of variance, a set of 18 genotypes showed significant effect of environment, genotype, and GEI on the γ-oryzanol and its constituent compounds. A large proportion of total phenotypic variance was found due to genotype, indicating high heritability of the trait. GEI is the second major contributor to the phenotypic variance of γ-oryzanol and its components, while the contribution of environment was found to be the least. CSR 23 was the superior genotype for γ-oryzanol content and stability based on AMMI, GGE biplot and WAASB stability models analyzed. Besides CSR 23, genotypes such as DHMAS-70γ-164-29, Chittimutyalu and HUR-200-57-1 were identified as stable and high γ-oryzanol producing lines. These superior, stable lines can be used as potential donors for improving γ-oryzanol content in rice. The present study assumes importance as the first report of GEI for total γ-oryzanol and its five components.