Water production function and optimal irrigation schedule for rice (Oryzasativa L.) cultivation with drip irrigation under plastic film-mulched

This study determined the Water Production Function (WPF) and Optimal Irrigation Schedule (OIS) for rice (Oryzasativa L.) cultivated with drip irrigation under plastic film. Six different field capacity levels were established, 100% (W1), 90% (W2), 80% (W3), 70% (W4) and 60% (W5). The results showed that, the rice growth and yields and quality were significantly affected by the different irrigation treatments. The rice height and yield decreased from W1to W4, the W2 is the highest yield. The lower the amount of irrigation water applied was, the higher the Irrigation Water Use Efficiency values were. A WPF model was established for this cropping system, and the water sensitivity indices calculated by the mathematical model showed that the crop water sensitivity decreased in the order booting stage > flowering stage > tillering stage > filling stage. Based on this result, the OIS determined by the dynamic solution of several models was as follows: the optimal irrigation levels were 750 m(3) ha(-1) in the tillering stage, 2125 m(3) ha(-1) in the jointing-booting stage, 1050 m(3) ha(-1) in the heading-flowering stage and 325 m(3) ha(-1) in the milk stage. The WPF and OIS developed in this study provide a theoretical basis for the implementation of rice cultivation with drip irrigation under plastic film in arid regions of China.