Investigation of Drought Stress Indices and Relationships between Yield Components of Bread Wheat Cultivars (in Qazvin Region)

In this research, the bread wheat cultivars were investigated for determining the optimal cultivation cultivar. The main treatments were included the rainfed and irrigated cultivation, and the sub-treatments were included the cultivars of Sorkh tokhm (E1), Backcross Roshan (E2), Bam (E3), Azar2 (E4) and Kavir (E5). The experiment was performed in a randomized complete block design with three replications. The yield components (average in the rainfed and irrigated cultivations) were measured for Sorkh tokhm, Backcross Roshan, Bam, Azar2 and Kavir cultivars by 5322, 6702, 6122, 4621 and 4259 kg. ha-1 (grain yield) and 4790, 6402, 5411, 4299 and 4013 kg. ha-1 (straw yield) respectively. From the rainfed to irrigated cultivation, the yield was increased by 57%, 100%, 82%, 41% and 36% (in total yield), 40%, 93%, 60%, 30% and 29%, (in straw yield) and 75%, 106%, 105%, 53% and 43% (in grain yield), respectively. The relationship between grain yield (X) and straw yield (Y) was fitted as Y=0.867X in the irrigated cultivation and Y=1.017X in the rainfed cultivation. For evaluation the cultivars susceptibility to drought stress, were used the indices of MP, GMP, TOL, SSI and STI for grain and straw yields components. As a result, for selecting the optimal cultivar (in Qazvin region), the priority was given to cultivars of Backcross Roshan, Bam, Sorkh tokhm, Azar2 and Kavir, respectively. If water is supplied for irrigation, the yields of grain and straw will increase to double in the cultivation of Backcross Roshan cultivar.