Effect of drought stress, nitrogen fertilizer and sowing date on agro-physiological characteristics of two millet cultivars

In order to investigate the effect of drought stress, nitrogen chemical nutrition and sowing date on agrophysiological characteristics of millet cultivars, a split-split plot experiment was conducted in a randomized complete block design with three replications at the Research Farm of Isfahan University of Technology, in 2015. Two millet cultivars (Bastan and Pishahang) were planted in two sowing date (June 22 and July 6) under two irrigation regimes (55% and 85% depletion levels of the available soil water) and two nitrogen fertilizer levels (available amount and 112.5 kg ha-1, nitrogen from Urea fertilizer, N= 45%). The results showed that drought stress caused a significant reduction in grain and biological yield by decreasing chlorophyll content, leaf area index, relative water content, membrane stability index, spade, quantum efficiency of photosystem II, height, panicle length and 100-seed weight. Nitrogen application resulted in a significant increase in grain and biological yield in normal irrigation, but did not have a significant effect on yield in drought stress. In normal irrigation, grain and biologic yield were more at June 22 than July 6, while in drought stress condition, delay in sowing date resulted in improved yield compared to June 22. Bastan had lower electrolyte leakage and more membrane stability in drought stress. The results showed that delay in sowing date by modulating the temperature conditions could be a suitable solution for yield loss compensating under drought stress conditions, also under stress conditions, nitrogen application should be applied at a higher level to determine optimum amount of nitrogen application.