Study of drought stress effect on some growth indices and yield and yield components in 20 genotypes of bread wheat

An experiment was carried out with twenty genotypes in Kurdistan province in two growing season years. Grain yield was highest for the third group with 219.87 g/m2. Grain yield was the lowest in the first group (173.40 g / m2), which was not significantly different with the second group (191.22 g/m2). But in second crop year, the highest rate of radiation use efficiency related to the first group with 2.69. In contrast, the lowest radiation use efficiency was related to second and third groups with 2.57 and 2.54, respectively. The highest grains yield was observed in the second group with 315.40 g/m2. In contrast, the lowest amount of grain yield was related to the third group with 253.75 g/m2. Based on the results of biplot, in the first year of cultivation, high yield genotypes included ‘G14’ (263.00 g/m2), ‘G20’ (264.50 g/m2), ‘G18’ (214.00 g/m2) and ‘G19’ (222.50 g/m2) has a higher correlation with biologic yield, grain yield, radiation use efficiency, harvest index, root Length, number of panicles, 1000-grain weight, root dry weight and number of grain per panicle traits. In the second year of cultivation, high-yield genotypes included ‘G7’ (356.42 g/m2) and G9 (356.75 g/m2) have high correlation with number of grains per square meter trait. These results indicate that under stress conditions, more traits play a role in justifying the grain yield of wheat.