Effects of genotype and environment on seed yield and quality of rice

Seed yield and seed quality determine much of the value of rice (Oryza sativa L.) crops to the producers. The effects of genotype and environment on seed yield and quality were investigated using 12 rice genotypes grown during 3 years (2000-2003) at four different sowing dates in India, where detailed environmental data were collected. Yield, seed weight, proportion of seed setting and quality in terms of potential seed longevity, proportion of discoloured seeds, seed leachate conductivity and percentage germination were evaluated. The results were subjected to analysis of variance and the influence of environmental factors was evaluated by correlation analysis. Analysis of variance suggested that proportion of seed setting, seed leachate conductivity, potential seed longevity, percentage seed germination and proportion of seed discoloration were influenced more by environmental effects than by genotypic effects. In contrast, yield, panicle number, seed weight, and proportion of high-density grains were influenced more by genotypic than by environmental effects. The significant interaction effects of genotype and environment for all characteristics were attributed to differential resistance of genotypes to lodging (caused by increased plant height, low radiation and excessive rain at the time of grain filling) and were associated with fewer particles harvested, lower seed setting and lower seed weight. Correlation analysis suggested that warm weather conditions with high solar radiation and without excessive rains during grain filling stage gave the best rice seed yield with high quality.