Physiological, biochemical and yield responses of wheat cultivars to deficient water stress

Two similar and concurrent experiments were carried out in the Agricultural Research Center of Islamic Azad University, Kermanshah Branch and Agricultural Research Center of Islamabad during 2016-2017. The experiments were performed in a split-plot format in a randomized complete-block design based on 3 replications. The main plots were assigned to 4 different regimes of irrigation: (I1) full irrigation during the growth period followed by 50% of the soil moisture depletion; (I2) water deficit stress from the start of the flowering stage (Z61) to the milking stage (Z77) associated with irrigation after 80% of the soil moisture depletion; (I3) water deficit stress from the beginning of the flowering stage (Z61) to the ripening stage (Z93) followed by irrigation after 80% of the soil moisture depletion; and (I4) water deficit stress from the start of the milking stage (Z77) to the ripening stage (Z93) followed by irrigation after 80% of the soil moisture depletion. The 3 cultivars of C1 (Sirvan), C2 (Pishtaz), and C3 (Marv dasht) were treated using the allocated sub-plots. The results revealed that by increasing the drought stress intensities on the wheat cultivars, Grain Yield (GY), Relative Water Content (RWC), and Total Chlorophyll Content (TCC) were decreased except for Proline Content (PC). Sirvan cultivar subjected to the treatment of drought stress (I3) led to the highest reduction in RWC and TCC compared to the control treatment (I1). The results of this study indicated that the wheat cultivars of Islamabad Agricultural Research Center had higher GY (5129 kg.h-1), TCC (58 mg. g-1 fr.wt.), and RWC (92%) values than those of the Agricultural Research Center of Islamic Azad University, Kermanshah branch