Response of Rice Yield and Soil to Sulfur Application under Water and Salinity Stresses

TWO FIELD experiments were conducted at El-Sirw Agricultural Research Station, Damietta Governorate, Egypt during summer seasons of 2015 and 2016 to investigate the effect of three irrigation intervals ( 3 , 6 and 9 days ) and four soil application of sulfur rates ( 0 , 200 , 400 and 600 kg S/ ha ) and their interaction on the soil properties , growth characters, yield and yield components as well as water productivity of rice under saline soil conditions. In each experiment , strip plot design with four replications was used , where the horizontal plots were devoted to the irrigation intervals and the vertical plots were allocated by the sulfur rates. Irrigation every 3 days significantly decreased the values of the soil chemical properties studied , i.e. soil acidity (pH) , electrical conductivity (EC) and bulk density but significantly increased growth characters , i.e. chlorophyll content, leaf area, dry matter production and number of tillers/ hill and plant height as well as yield and yield components, i.e. number of panicles/ hill , panicle length , panicle weight, number of filled grains/ panicle , fertility % , 1000-grain weight , grain and biological yields/ ha and harvest index as compared with irrigation every 6 and 9 days. However , irrigation every 9 days significantly increased the number of unfilled grains/ panicle. Increasing soil application of sulfur rates up to 600 kg S/ ha decreased the values of soil properties (pH , EC and bulk density) as well as significantly and gradually increased the aforementioned growth characters as well as yield and yield components but significantly decreased number of unfilled grains/ panicle. The interaction effect between irrigation intervals and sulfur application rates , indicate that grain and biological yields/ ha were increased by the application of sulfur rates up to 400 kg S/ ha under short irrigation interval (3 days) and up to 600 kg S/ ha under medium and and long irrigation intervals (6 and 9 days). The irrigation of rice plants every 3 days consumed the largest amount of irrigation water, while prolonging the irrigation intervals up to 6 and 9 days led to a gradual decrease in the amount of irrigation water consumed by 12.99 and 37.31% , respectively compared with the irrigation every 3 days. Irrigation of rice plants every 6 days with the application of sulfur at a rate of 600 kg S/ ha produced the highest values of water productivity (0.296 kg/ m^3 water) as an average of both seasons, indicating to the beneficial effect of the application of sulfur for improving soil properties, growth, yield and yield components as well as water productivity especially under prolonged irrigation interval in saline soil condition.