Effects of fall nitrogen rates on rainfed bread wheat yield and yield components in drought condition

ABSTRACT: In this study fall nitrogen application effects on agronomic characteristics of dryland bread wheat genotypes was investigated. This project was conducted in a split-plot arrangement based on randomized complete block with four replications and ten nitrogen rates (0, 15, 20, 30, 40, 45, 60, 80, 90 and 120 kg N.ha-1 from urea) in main plot and five rainfed bread wheat genotypes in sub-plot in Maragheh Dryland Agricultural Research Institute (DARI) station in 2007-2008. Results showed that application of nitrogen increased biological yield, grain yield, harvest index, degree of productivity, number of spike in m2 and plant height significantly at P < 0.01 and increased TKW, number of fertile tiller and flag leaf dry weight significantly at P < 0.05. Nitrogen application increased grain yield 47%, biological yield 85%, number of spike in m2 83%, number of fertile tiller 30%, plant height 20% and flag leaf dry weight 17%. Average nitrogen requirement of rainfed wheat for obtaining of 90% maximum grain yield for genotype Azar2, Sardari, Sardari39, Sardari101 and Rasad calculated 42, 46, 45, 38 and 35 kgN.ha-1 from urea in drought year with 137 mm annual precipitation. It can be concluded that application of nitrogen can verify rainfed wheat genotypes agronomic characteristics and grain yield.