Responses of grain yield and yield components of wheat to supplemental irrigation in dryland conditions

In order to evaluate responses of grain yield and yield components of wheat to different amount of supplemental irrigation in dryland conditions, a field experiment was conducted in research farm of College of Agriculture, Shiraz University during 2004-2005 and 2005-2006. The supplemental irrigation treatments including dryland conditions, irrigation at stem elongation, booting, flowering and grain filling were main plots and two cultivars, Agosta and Fin-15 were subplots and three levels of nitrogen including zero, 40 and 80 kgha-1 were sub sub plots. The results showed that in both years, the highest number of spike m-2, spikelet spike-1, number of kernel spike-1 and grain yield were obtained from irrigation at stem elongation stage whit 80 kg N ha-1 and from Fin-15 variety and the lowest were obtained from Agosta variety at N control treatment under dryland conditions. Also the highest thousand kernel weight was obtained from supplemental irrigation at grain filling stages.. The results of this research showed a strong correlation between number of spike m-2, spikelet spike-1, number of kernel spike-1, thousand kernel weight and grain yield with the amounts of applied water at supplemental irrigation treatments and whit increasing of applied water the above mention parameters also increased. The highest grain yield in both years was obtained from supplemental irrigation at stem elongation stage. The supplemental irrigation in 2004-2005 and 2005-2006 growing season increased the grain yield 200 and 221 percent respectively. According to results of this experiment, supplemental irrigation increased wheat production through increasing yield and yield components in dryland conditions. Thus using of supplemental irrigation at stem elongation stage with supply of adequate water could increase grain yield of rainfed wheat in dryland conditions.