The microsprinkler irrigation system influences the growth, yield, and water productivity and nutrient uptake of aerobic rice under humid subtropical climatic conditions

Properly managed microsprinkler irrigation of rice is an efficient and viable alternative to traditional flood irrigation methods for enhancing crop and water productivity in water-scarce regions. Field experiments were conducted for two consecutive summer seasons (February to June) of 2017 and 2018 on sandy loam soil with three levels of irrigation, viz., the ratios of crop evapotranspiration (ETc) were 1.25, 1.0 and 0.75, and a microsprinkler, including surface irrigation, was used to evaluate the growth parameters, yield attributes, yield, crop water productivity (CWP), root-zone soil water dynamics and nutrient utilization of aerobic rice. The results showed that microsprinkler irrigation at 1.25 ETc resulted in the maximum plant height, dry matter yield, leaf area index, number of effective tillers m⁻², number of panicles m⁻², number of filled grains panicle⁻¹, relative leaf water content, 1000-grain weight, grain yield (3.76 t ha⁻¹), straw yield (5.15 t ha⁻¹), harvest index, chlorophyll content and grain nutrient uptake. The highest CWP (0.92 kg m⁻³) was found under microsprinkler irrigation at 1.0 ETc, while under deficit irrigation at 0.75 ETc, the microsprinkler exhibited greater root length, root volume and water savings than did surface irrigation. Greater soil water contents and root-zone soil water storage and depletion at all growth stages were recorded under microsprinkler irrigation at 1.25 ETc. A strong second-degree polynomial relationship was detected between grain yield and the amount of irrigation water. The optimal irrigation requirement for aerobic rice grown in the Indo-Gangetic Plains of Eastern India was estimated to be 325 mm to maximize yield and water utilization.