Effect of Alternating Irrigation on Yield, Yield Components and Water Productivity in Direct Seeding of Rice in Kazerun Region

Rice is one of the high water consuming crops and it is important to utilize methods in its production to promote water use efficiency. In order to achieve this purpose, a split plot experiment was conducted in direct-seeding of rice in Kazerun region of Fars province, Iran, in 2007. Five irrigation treatments (full-season flooding, full-season alternating, flooding until tillering stage, flooding until stem elongation, and flooding until flowering) were arranged in main plots and subplots consisted of three rice cultivars (Fajr, Shafagh and native Champa). The results indicated that Fajr cultivar with 4538 kg/ha and Champa with 1734 kg/ha produced the highest and the lowest grain yield, respectively. Alternating irrigation caused reduction in plant height, biological yield and grain number and weight. Grain yield in alternating irrigation, flooding until tillering, flooding until stem elongation and flooding until flowering was reduced 30, 26, 26 and 4 percent, respectively, as compared to full-season flooding irrigation; while, water use efficiency in these treatments was 92, 60, 0 and 22 percent higher than full-season flooding irrigation. In all alternating irrigation treatments water consumption was lower than flooding. Despite lower grain yields in these treatments, the water use efficiency was improved. The highest water use efficiency was observed in full-season alternating irrigation treatment. Therefore, according to the results, flooding irrigation until flowering or stem elongation could be considered for acceptable grain yield and water use productivity, instead of full-season flooding irrigation, in future researches.