Effects Of Supplemental Irrigation And Nitrogen Rates On Yield And Yield Components Of Rainfed Wheat Cultivar Sabalan

In order to investigate the effects of supplemental irrigation and nitrogen rates on yield and yield components of wheat, a field experiment was conducted as split plot arranged in a randomized complete block design (RCBD) with three replications, during 1999-2002 at Maragheh Agricultural Research Station of Dryland Agricultural Research Institute (DARI). The treatments included four levels of irrigation (rainfed, 1/3, 2/3 and 3/3 of full supplemental irrigation) as main plots and fiveN rates (0, 30, 60, 90 and 120 kgNha-1) as subplots. Grain, Straw and biological yield, harvestindex, height, kernel number per spike (SIP) and 1000KWwere determined from the middle of each plots. Yields of rainfed conditions varied with seasonal rainfall and its distribution, with all main factors had significant effects. With irrigation, crop response were generally significant up to 60 kgNha-1. Optimum level of supplemental irrigation was 1/3 of full supplemental irrigation with 60 kgNha-1 had maximum water use efficiency (30kgmm-1) and good yield. (minimum water use especial one time irrigation at planting time).