Evaluation the growth characteristics, yield and yield components of wheat and barley under water and nitrogen stress conditions

Water and nitrogen stress are among the most important factors that reduce wheat yield. To study the effect of water and nitrogen stress on some morphological traits, grain yield and yield components of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) and determination the effective traits on yield, a split-plot factorial field experiment was carried out at Research Field of the School of Agricultural and Natural Resources University of Tehran, Karaj, in 2016-2017, in a randomized complete blocks design with 3 replications.The main factor was water stress at two levels, (No water stress and 40% of water requirement) and the sub factors included the combination of nitrogen fertilizer at two levels (0 and 200 kgha-1 of N) and wheat (Sivand and Pishtaz) and barley (Fajr 30) cultivars. Water and nitrogen stress reduced all traits such as 50 percent reduction in grain yield. In terms of water stress, the highest correlation was observed between grain yield and biological yield, peduncle length, number of grain per spike, spike dry weight and plant (more than 75%). Stepwise regression showed 5 and 3 varialbles significantly explain the variation of yield under normal irrigation stress conditions, respectively. Results of factor analysis revealed that factors justified 98.4% and 99.5% of total variance variation under normal and stress conditions, respectively .According to the results, biological yield was the most effective variable on grain yield under water and non-stress conditions; therefore, it could be used as a marker for yield.