Effect of Deficit Irrigation at Different Growth Stages on Wheat Growth and Yield

In order to evaluate the effect of deficit irrigation at various growth stages on wheat growth and yield, a field experiment was conducted in the 2008-2009 growing season based on the completely randomized block with four replications at the experimental farm of the College of Agriculture, Shiraz University, Shiraz, Iran, located at Badjgah. Treatments involved 13 irrigation regimes which applied in stem elongation, heading and grain filling growth stages. The highest seed yield (4,333 kg·ha -1 ) and the lowest ones (1,377 kg·ha -1 ) were obtained from T1 (100% field capacity (FC) in all growth stages) and T13 (50% FC in all growth stages), respectively. With limitation in water amount seed yield was diminished, but this trend was not significant at T4 (100%, 100% and 50% FC) and T11 (100%, 100% and 75% FC). Stepwise regression results revealed that, seed number per spike had the largest contribution (partial R 2 = 0.72) in seed yield variation. Also at T1, T4, and T11 treatments (well water treatments) as well as T13 (sever stress) head number m -2 contribute most in seed yield determination (partial R 2 = 0.96). It can be concluded that water shortage during the grain filling period and its allocation to the other consecutive crop, can increase crop production in southern regions of Iran.