Effects of Nitrogen fertilizer on yoeld and som physiological charachteristics on two drought resistance and susceptible wheat (Tritticum aestivum L.) cultivars in response to water stress

Drought stress and nutrient deficiency are the major limiting factors in crop production around the world. In order to investigation the effects of nitrogen on physiological characteristic and yield of two winter wheat varieties under drought stress, a pot experiment was carried out in a factorial experiment in randomized complete block design with three replications at the University of Kurdistan during 2008. Treatments included drought stress (irrigation at soil water potential -3 bar as control and irrigation at soil water potential -13 bar as water deficit), nitrogen fertilizer (control treatment as non fertilizer application, 0.35 and 0.70 g nitrogen per pot), applied on Zarrin and Azar2 of wheat cultivars. Results showed that despite of lower values of SPAD in drought stress condition, it was increased in each of nitrogen application. Under drought stress treatment, however we observed a reduced amount of photosynthesis (Pn), intercellular CO2 concentration (Ci), transpiration (E) and mesophyll conductance (MC). After exposure to recovery condition, the levels of photosynthesis and mesophyll conductance in Azar2 was significantly higher than Zarrin cultivar. Nitrogen fertilizer application under non stress condition caused in increasing trend of mesophyll conductance and concentration of soluble proteins was also increased.