Evaluation of yield, radiation and water use efficiency of drought resistant and susceptible wheat cultivars under different irrigation levels

A field experiment was conducted in order to evaluate drought stress on yield, radiation use efficiency (RUE) and water use efficiency (WUE) of drought resistant and susceptible cultivars of wheat at agricultural faculty research field of University of Kurdistan during 2012-2013 growing season. The experiment was split plots based on randomized complete blocks design with three replications. The main plots were different levels of irrigation (FI as irrigation based on crop water requirement, 75%FI, 50%FI and 25%FI as irrigation based on 75%, 50% and 25% of crop water requirement in FI treatment, and NI as treatment without irrigation) and subplots were three wheat cultivars (Azar2 (resistant), Gascogen and Sayonce (susceptible). Analysis of variance showed that the differences among irrigation treatments and studied cultivars were significant for economical yield (EY), biological yield (BY), and WUE in terms of economical (WUEe) and biological (WUEb) yield. The amount of EY, BY, WUEe, WUEb, and RUE were decreased with reduce in water availability rather than control treatment. The overall results showed that the amount of EY, BY, WUE and RUE of resistant cultivar were greater than susceptible cultivars. However, the harvest index of susceptible cultivars was greater than resistant one. In general, increasing WUE and RUE under drought stress treatments were two most important factors determining performance excellence of resistant cultivar rather than susceptible cultivars.