Effect of Irrigation and Nitrogen Fertilizer Levels on Physiological Characteristics of Four Varieties of Barley (Hordeum vulgare L.)

This field study was conducted in a factorial split plot experiment based on randomized complete block design with three replications to evaluate the effect of irrigation and nitrogen fertilizer levels on physiological characteristics of four varieties of barley (Hordeum vulgare) during 2012 in Azad University of Miandoab. Irrigation levels were full irrigation, cutting off irrigation at boot stage (code 40 scale zadoks) and cutting off irrigation at flowering stage (code 60 scale zadoks). Nitrogen levels were 20, 40, 60 and 80 kg ha-1. Varieties under study were ‘Makuyi’, ‘Valfajr’, ‘Sahra’ and ‘Jonoob’. Traits studied were seed yield, flag leaf area, chlorophyll content of flag leaf and proline content of flag leaf, and peducle length. The results showed that highest grain yield, flag leaf area, chlorophyll content of flag leaf and proline content were obtained by using 80 kg.ha-1 nitrogen. Data collected also showed that at 80 kg.ha-1 nitrogen and full irrigation, the highest and lowest grain yield, flag leaf area, chlorophyll content of flag leaf belonged  to ‘Makuyi’ and Jonoob, respectively. However, cuuting off irrigation at boot stage resulted in highest and lowest grain yield, flag leaf area, chlorophyll content of flag leaf to Jonoob and Valfajr, respectively. Cutting off irrigation at flowering stage decreased grain yield and increased proline content in ‘Makuyi’ and ‘Valfajr’. However, lowest reduction in grain yield, and highest increase in proline content were measured in ‘Sahra’ and ‘Jonoob’ varieties. Decreasing slope of regression curves was higher in ‘Makuyi’ and ‘Valfajr’. This indicates that cutting off irrigation at flowering stage reduced yield and increased proline content of these varieties compared to ‘Sahra’ and ‘Jonoob’.