Effect of Foliar Application of Phosphorus and Water Deficit on Yield and Yield Components of Winter Wheat (Cultivar Alvand)

In order to study the effects of foliar application of phosphorus (P) and water deficit on yield and yield components of winter wheat (Triticum aestivum L., cv. Alvand), a split-plot experiment, with completely randomized blocks design and three replications, was carried out at the Research Farm of Boyer Ahmad Agricultural and Natural Resources Research Station, 13 km west of Yasouj, in 2008-2009. The main plots were irrigation at three levels (1- full irrigation (control), 2- deficit irrigation from the stem elongation to booting stage, and 3- deficit irrigation from booting stage to the end of growth period) and the subplots were five levels of foliar application of P fertilizer (0, 3, 6, 9 and 12 kg/ha KH2PO4). The results showed that the effects of different irrigation regimes and foliar application of P were significant on all traits, and their interaction was significant on plant height, number of grain per spike, grain yield and biological yield. Full irrigation and foliar application of 6 kg/ha P produced the highest grain and biological yield (6000 and 14170 kg/ha, respectively) and deficit irrigation from the stem elongation to booting stage without foliar application of P produced the lowest grain and biological yield (2920 and 8219 kg/ha, respectively). Foliar application of P affects significantly the evaluated traits only in drought-stress treatments and its effect was not significant in full irrigation treatment. In general, foliar application of 9 kg/ha P compensated the losses in wheat due to drought stress.