Study of correlation between grain weight-affecting traits and determination of effects of some physiological parameters on grain yield of autumn genotypes of wheat under optimum and drought stress conditions

The current study was carried out to study the traits affecting grain weight and the effects of some physiological parameters on grain yield of autumn wheat genotypes under optimum and drought stress conditions. So, 16 bread wheat genotypes were evaluated under optimum moisture conditions during growth season and under post-anthesis drought stress until physiological maturity based on a randomized complete block design with two replications. The measured traits included grain yield, grain weight, retranslocation of reserves from stem to grain, the efficiency of stem in translocating its reserves, the partial share of stem reserves in yield, biological yield, harvest index and stress tolerance index (STI). The results showed that grain yield had a high, positive correlation with biological yield under both optimum and stress conditions. The highest correlation coefficients were observed between grain weight with biological yield, the number of grains per spike and harvest index. Under stress conditions, only harvest index and yield had significant correlations with stress tolerance index of genotypes. Stepwise regression analysis under optimum and stress conditions showed that biological yield and harvest index were the most important components which explained the variations of grain weight.