Effects of water stress conditions on Yield, Harvest Index, and Sterility in Wheat Genotypes (Triticum aestivum).

Plants are exposed to drought stress in field conditions. The occurrence of these droughts has imposed a very harmful effect on the agricultural and economic sectors of the country. Response of plants to water stress depends on the type, intensity, and duration of stress, plant species and the stage of stress occurrence. Investigate has shown that water stress before the tillering stage reduces the number of fertile tillers, stress at the flower inoculation stage reduces the weight and number of seeds and causes cluster sterility, and moisture stress during the grain filling period produces wrinkled seeds. The study aimed was to investigate the effect of different water stress conditions on yield, harvest index and sterility at the end of the cluster in wheat genotypes.

To analyze the effects of three different humidity regimes on yield, yield component and apical sterility of wheat, three different experiments were carried out in randomized completey block designs with three replications. The three different humidity regimes included normal conditions (without stress), water-stress at the meiosis stage and continuous water stress (30% of Field Capacity). Ten different wheat genotypes including Alvand, Roshan, Back cross Roshan, Ehdaei 81، Ehdaei 82، Ehdaei 79, Oxley، ChineseSpring، DN11 and Line 604 were evaluated in this experiment.

Results indicated that the responses of the genotypes to the water-stress condition were different. Analysis of variance showed highly significant variation for most of the characters under study. Both stress conditions, either meiosis stress or continuous stress, reduced all the characters of genotypes compared with non-stress conditions. Among the genotypes under study, Oxley indicated the highest amount of yield in both the meiosis stage and continuous water-stress conditions. On the other side, Line 604 showed the highest number of seeds and lowest sterile florets at both meiosis stage and continuous water-stress conditions. The highest rate of apical sterility in water-stress at meiosis stage and 30% of field capacity in Alvand genotype was observed.

Results showed that drought stress in all types of stress reduced the evaluated traits. Due to stress the number of sterile florets increased and yield decreased. Stress in the meiotic stage had a significant effect on increasing the apical sterility and total Sterility, and stress of 30% of field capacity was effective in reducing grain yield and harvest index and increasing the number of the sterile claw in wheat genotypes.