INFLUENCE OF LATE-SEASON NITROGEN APPLICATION ON GRAIN YIELD, NITROGEN USE EFFICIENCY AND PROTEIN CONTENT OF WHEAT UNDER ISPARTA ECOLOGICAL CONDITIONS

The research has been conducted under Isparta ecological conditions during the 2006-2008 growing seasons. The purpose of the study was to determine the effects of late-season N application on grain yield, nitrogen use efficiency, nitrogen uptake efficiency, nitrogen utilization efficiency and grain protein content of wheat. The experiment was set up as Randomized Complete Block Design with a split-plot arrangement with three replications. Wheat cultivars were main plots, the nitrogen application times were subplots. Bread wheat cultivars (Gun-91, Gerek-79 and Altay-2000) were used. Nitrogen was applied as conventional N (two equal amounts at the time of seed sowing and tillering stage) and late-season N application (one-third of was applied during sowing, one-third at the tillering stage and the rest was applied as foliar at post-pollination growth stage). Effects of late-season foliar N application on grain yield, nitrogen use efficiency, nitrogen uptake efficiency, nitrogen utilization efficiency and grain protein content of wheat were observed. Grain yield, nitrogen use efficiency, nitrogen uptake efficiency, nitrogen utilization efficiency and grain protein content of wheat in both years of the study were significantly affected by N application time. The results showed that the grain yield, nitrogen use efficiency, nitrogen uptake efficiency and grain protein content were higher in the late-season N application than those of in the conventional N application in both years. But, nitrogen utilization efficiency was higher in conventional N application than late-season foliar N application in both years. The highest grain yield (3281 kg ha(-1)), nitrogen uptake efficiency (71.3 %) and grain protein content (12.6 %) were obtained from Altay-2000 with cultivar x late-season N interaction in the second year. The highest nitrogen use efficiency (14.5 To) was obtained from Gun-91 with cultivar x late-season N interaction; and highest nitrogen utilization efficiency (37.6 %) was determined from Gerek-79 with cultivar x conventional N interaction in the second year.