Genetics of grain filling rate and remobilization of stem reserves in bread wheat under terminal drought stress

To determine the gene action and inheritance of grain filling rate and remobilization of stem reserves in bread wheat, a 6×6 half diallel was performed. The F1 seeds along with parental varieties were evaluated under terminal drought stress at Islamic Azad University, Ardabil, Iran in 2018. Grain filling rate, effective grain filling period, remobilized dry matter, the contribution of remobilization in grain yield, remobilization efficiency of dry matter, carbohydrates remobilization efficiency, and specific weight of internodes were measured. Results showed the adequacy of the additive-dominance model in all of the characters except for the effective gain-filling period and contribution of remobilization in grain yield. The existence of partial dominance, complete dominance, and over-dominance was observed in control of the measured characters. Generally, broad sense heritability was high and ranged from 0.72 (carbohydrates remobilization efficiency) to 0.88 (grain filling rate). However, narrow sense heritability ranged from 0.17 (carbohydrates remobilization efficiency) to 0.66 (grain filling rate). Among the traits, grain filling rate had the highest narrow sense heritability (0.66) followed by the remobilized dry matter (0.46) and specific weight of internodes (0.44). There was also a positive relationship between dominance effects and the specific weight of internodes, where dominant alleles were favorable. Based on Griffing’s method, Rasad, Konya2002, and Pishtaz had higher general combining ability (GCA) and consequently favorable alleles for the grain filling rate. However, for remobilization, Rasad and Konya2002 had higher GCA.