A study was conducted at karaj Experiment Station, University of Tehran, to evaluate the effect of application of limited amounts of water at various growth stages, and different levels of nitrogen on yield and other agronomic characterjstic of irrigated winter wheat (Karaj-1). Four irrigation treatments, namely,I1=preplant (PP), I2SPP+Jointing(JT), 13=PP+JT+Flowering(FL), 14PP+JT+FL+ Grain Development (GD) were used. Nitrogen levels studied, were 0,30,60,and 90 Kg/ha. The experiment was laid out in split plot design with irrigation as main plots and nitrogen as subplots. Four replications were provided for each treatment. Characters studied were: grain yield, yield components, heading time, plant height, and grain protein content. The analysis of variance tor grain yield, 1000— kernel weight and grain protein content indicated highly significant differences among the four irrigation treatments. Nitrogen treatments differences were only significant for grain yield and grain protein content. yields and protein concentration increased with higher N rates, but supply of adequate soil moisture increased grain yield and decreased protein concentration. There was negetive correlation between yield and protein. The correlation coefficients ranged from r=—.60 to —.92 for different N levels The drought sensivity coefficients were estimated for the growth stages and the flowering stage had the greatest value.
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