Improving the performance of bread wheat genotypes by managing irrigation and nitrogen under semi-arid conditions Ul-AllahSami IqbalMuhammad MaqsoodShafique NaeemMuhammad IjazMuhammad AshfaqWaseem HussainMubshar 2018 <p>Wheat (<i>Triticum aestivum</i> L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors <i>i)</i> irrigation in main plots, <i>ii)</i> nitrogen in sub-plots, and <i>iii)</i> twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.</p>