Study of Regression Analysis of Rice Physiological Indices in Different Growth Stages under Khuzestan Condition

This study aimed to investigate the relationship between morphophysiological and phenology traits with grain yield to determine the best indices of direct and indirect selection in the field of genetic improvement of aerobic rice grain yield in Khuzestan province with 12 aerobic rice genotypes. The traits such as include the grain yield as the dependent variable and total dry matter, panicle weight, stem weight, LAI, CGR, NAR, LAR, SLA, ALW, LWR, L/S, SWR, PWR, LAD and BMD as independent variables, which were analyzed by stepwise regression at different growth stages to determine their effect on grain yield. The results showed that on 25 days after planting traits of L/S, SLA, LAI and leaf weight, on 50 days after planting traits of NAR, L/S, SWR, stem weight and BMD, on 75 days after planting traits of NAR, SLA, stem and LAR, on 100 days after planting traits of CGR, stem, L/S, LAR and PWR and on 125 days after planting traits of CGR, NAR, SLA, L/S and leaf affected the grain yield. In order from the beginning to the end of the growth, traits of L/S, NAR, panicle weight, CGR and CGR had caused the greatest changes in the grain yield. According to the critical period of growth, CGR was the most effective trait on the grain yield because of allocation of more assimilates in the reproductive growth instead of vegetative growth during grain filling period, thus it can be an important objective in the breeding researches.