A new method for providing water requirement of rice culture based on near-saturated soil matric potential

Water is one of the main important environmental factors limiting rice cultivation, in arid and semiarid regions like Iran. In order to evaluate the effect of growth inducers on sub-irrigation technology performance in rice water requirement, this field experiment was conducted as a factorial plot, based on completely randomized design with 6 replications, with two irrigation treatments (flooding and sub-irrigation with porous clay capsules), and two inducers (Mycorrhiza and salicylic acid) in 2016 at the research farm of GKU. Salicylic acid was used as seed treatment along with leaf spray in the concentration of 2 mM, two times in vegetative and reproductive growth. Mycorrhiza was used as root inoculation and was also mixed (20 gr.m-3) with the top 40 cm of soil. In this study, some morphological traits including plant height, the main panicle length, the weight of filled seeds, 1000-grain weight, weight of main panicle, the weight of whole panicles, grain yield, biological yield, water consumption, water productivity, water use efficiency and harvest index were measured, calculated, and assessed after harvesting. Grain yield for flood irrigation method for salicylic acid, mycorrhiza and control treatments were 5170, 4710, and 4202 kg.ha-1, respectively. While these values were 4985, 4807 and 4063 kg.ha-1 for the subsurface irrigation method, respectively. The results showed that rice grain yield, biological yield and harvest index were not significant in the two irrigation methods. But the water use efficiency and water productivity index in the subsurface irrigation system were significantly higher than the flood irrigation. Finally, the near-saturated soil matric potential method was able to increase the subsurface irrigation efficiency compared to the flood irrigation method at rice culture.