Improving Rice Production Sustainability by Planting Salinity-Tolerant Rice Cultivars and Reusing Agricultural Drainage Water

AbstractThe main producers of agricultural drainage water in Khuzestan province in Iran are the sugarcane agro-industries. As a result of the accumulation of drainage water in the region, environmental and social problems have arisen. In general, the salinity of this drainage water averages 6.3 dS/m throughout the year. The cultivation of salinity-resistant varieties of paddy rice can be considered as a suitable substrate for the optimal use of drainage water. In this regard, a study was conducted in one of the sugarcane fields in southern Khuzestan based on randomized complete block design with three replications. The main factor was three intermittent irrigation regimes using drainage water of sugarcane fields, which included daily irrigation (I0), one-day irrigation interval (I1) and two-day irrigation interval (I2). In addition, the subplots included three salinity-resistant rice lines (S1, S2, and S5), four drought-resistant rice lines (M2, M5, M7, and M12), a control cultivar “Hashemi” and a local cultivar “Hoveyzeh.” The results showed that with a significant reduction in applied water from the I0 to I1 and I2, the yield in I1 increased by 6% over I0, but the yield in I2 decreased by 30%. The highest and lowest water productivity were related to I2 and I0 at the rates of 0.13 and 0.06 kg/m3, respectively. In I1 irrigation regime, the local cultivar Hoveyzeh produced a yield of 2,444 kg/ha, while the salinity-resistant lines S1 and S5 produced acceptable yields of 2,385 and 2,263 kg/ha, respectively. According to the findings from monitoring the soil exchangeable sodium percentage (ESP), farm soils in both irrigation regimes I0 and I1 were nonsodic and saline. In I2, however, the soil profile status approached the sodic state as a result of the drying of the topsoil and the influx of salinity into the surface layer, resulting in a 17% increase in ESP. Consequently, when using agricultural drainage water for irrigation, leaching at the end of the growing season and drainage are necessary to remove salts. Based on the findings of this article, it is possible to maintain stability in rice production for a wide range of regions around the world with warm climates by reusing agricultural drainage water.