Effect of deficit irrigation regimes on yield, yield components and determination of the best drought resistance evaluation index of three bread wheat cultivars.

In order to study the effect of irrigation regimes on yield and yield components of three bread wheat cultivars, Triticum aestivum L., an experiment was conducted at the research farm of Islamic Azad university, Khorasgan Branch in 00-006. The experiment was carried out as split plot based on randomized complete block design with four replications. Three irrigation regimes (based on 70 mm (I), 90 mm (I) and 0 mm (I) pan evaporation) were arranged in main plots and three wheat cultivars including Ghods, Mahdavi and Roshan-backcross were planted in sub-plots. Results showed that I and I treatments was not significantly different in most yield and yield components measured traits. I treatment significantly reduced yield and yield components, but water use efficiency was not affected. Significant differences were observed in number of grain per spike, 000 kernels weight and grain yield among cultivars. Ghods and Roshan-backcross had highest and lowest numbers of grain per spike, 000 kernels weight and grain yield, respectively. Based on sensitivity and tolerance indices to water stress, Ghods showed better yield stability in response to increased water stress. The results indicated that irrigation of wheat after 90 mm cumulative pan evaporation could be save about % of irrigation water with no significant loss in yield, under conditions similar to this experiment.