Response of some wheat varieties to irrigation and nitrogen fertilization using ammonia gas in North Nile Delta region

Strategies of regulated irrigation and fertilization are one of the most practical ways in saving irrigation water and N-fertilizer of farmland in arid and semi-arid regions. A field experiments were conducted in the two winter seasons of 2012/2013 and 2013/2014 on clay soil to investigate the effect of 3, 4 and 5 irrigation events and their interaction with two N-fertilization levels using ammonia gas; 75 and 90 kg N fed ^-1 which represent 100% and 120% of nitrogen recommended dose, respectively on wheat water consumptive use, grain yield, yield components and water productivity (WP) of three Egyptian wheat varieties; Misr-1, Misr-2 and Sakha-94 and compare the estimated wheat crop evapotranspiration (ET_c) values computed using Hargreaves, Penman– Monteith and Class A pan methods with the measured actual wheat evapotranspiration (ET_a) to evaluate the suitable method for estimating the reference evapotranspiration in North Nile Delta conditions. The obtained results showed that the irrigation treatments (3 events) gave the lowest values for water consumptive use, grain, straw, biological yield and 1000-grain weight. Nitrogen fertilizer in ammonia up to 90 kg N fed^-1 decreased all characters studied except grain yield which has no any significant differences between both N levels. Significant differences were detected among the three wheat varieties in all characters studied during both seasons and their interaction with the other treatments combined. Misr-1 cultivar was superior and gave the highest value of all studied characters and yield response to water factor (K_y) followed by Misr-2 while Sakha-94 showed the lowest values in all studied characters. Thus, Misr-1 cultivar proved to be more tolerant cultivar to drought followed by Misr-2 and Sakha-94. WP decreased with increasing irrigation events and nitrogen levels, and reached the maximum values at three irrigation treatments (3 events) and at 90 kg N fed^-1. So, irrigating the wheat 4 events during growing seasons and application of 75 kg N fed^-1 in the form of ammonia gave the highest values of yield and yield components of Misr-1 wheat cultivar under North Nile Delta condition.