Evaluation of single irrigation and nitrogen rates on rainfed wheat under drought condition

In rainfed areas of Iran, cereal yields are low, variable and mainly as a result of inadequate and erratic seasonal rainfall and associated management factor, such as late sowing date (or late crop germination). In order to investigate the effects of single irrigation and nitrogen on bread wheat (Triticum aestivum L. Var. Sabalan) a field experiment was conducted as split plot arranged in a randomized complete block design (RCBD) with three replications in 1999-2000 at Dryland Agricultural Research Institute (Maragheb station). Total seasonal rainfall was 210.6 mm. The treatments included four levels of single irrigation (Rainfed 37, 73 and 110 mm irrigation water use) as main plots and six N rates (0, 30, 60, 90, 120 and 150 kg.N.ha-1) as sub plots on Sabalan rainfed wheat variety. The grain, straw and biological yields, harvest index, height and TKW determined from the middle of each plots. Results showed that correlation of grain yield with all variables positive + significant. Optimum level of single irrigation at planting time was 37-73 mm of water use combined up to 48 kg.N.ha-1. Thus, when limited SI is combined with appropriate management, grain wheat production can be substantially and consistently increased in this semi arid zone.