Dlallele Cross Analysis of Several Physiological Criteria Related to Drought Resistance in Wheat

An experiment was conducted on the FJ generation from a half-diallel set of crosses involving two drought tolerant (Roshan and Kal-Haydary), three moderately tolerant (Bayat, B.C Roshan and Nick-Nejad) and three sensitive (Ghods, Falat and Darab2) genotypes of wheat to study gene action of rate of water loss (RWL) from excised-leaf, initial water content (IWq, air-canopy temperature difference (delta T=Ta-Tc) at booting and anthesis stages, and leaf water potential (LWP) and leaf osmotic potential (LOP) at the anthesis stage of development. Highly significant differences were observed between genotypes for all traits except for IWC (at booting) and delta T (at booting and anthesis at 10-11 h). General combining ability (GCA) and specific combining ability (SCA) mean squares, and GCA/SCA ratios were significant for all traits, noting the importance of additive gene action. Non-additive gene action had a major role in delta T at anthesis. Narrow sense heritability ranged from 46% for delta T at anthesis to 72% for RWL at booting and anthesis stages. Heterosis was not important for any trait. The genotype Kal-Haydary was the best general combiner for all traits except for delta T anthesis in which Roshan was better.