Abstract:
Abstract: Studies on how to improve the yield of rice, which are mostly affected by water and fertilizer, are receiving more and more attention. However, little is known about the coupling effect of irrigation and fertilizer on rice’s yield and water production efficiency (WPE). This study aimed at investigating the relations of water and fertilizer with the yield of rice cultivated in aerobic soil with drip irrigation under plastic film. The field experiments were conducted to establish yield model of water and fertilizer coupling of rice. Two groups of tests were set up including a preliminary test conducted in Yinchuan Xixia in 2012, and verification test conducted in Yinchuan Xixia in 2013 and Yinchuan Helan in 2014.The annual average rainfalls were 208, 260 and 300 mm for the three year. By quadratic current rotary combination method, 3 treatments of irrigation quota, N and P2O5 fertilizers with 5 levels for each were designed. Each plot was 25 m in length and 1.4 m in width, and plots were separated by 50 cm deep plastic film to prevent the cross penetration of water and fertilizer. The drip tapes were laid under plastic film, the dripper flow rate was 2 L/h. The rice variety was 96D10. Ternary quadratic regression model was used to fit relationship between yield and three treatments in 2012. The results showed that the model could well fit the relationship between the actual yield and irrigation, N and P fertilizer with the determination coefficient R2 of 0.981. The main factor analysis for the model revealed that the effects of three treatments on yield was ordered in irrigation quota>N>P2O5 fertilizers. In addition, the model was used to obtain optimal combinations of treatments for target yield and results showed that: 1) when the target yield of rice was 5000-6500 kg/hm2, the irrigation quota should be 2218.9-3087.3 m3/hm2, the N and P2O5 fertilizers was 131.7-236.9 and 66.1-109.5 kg/hm2, respectively; 2)when the yield of rice was 6500-8000 kg/hm2, the irrigation quota should be 4219.6-5157.6 m3/hm2, and the N and P2O5 fertilizers was 150.4-250.9 and 62.8-107 kg/hm2; 3)when the yield of rice was 8000-9500 kg/hm2, the irrigation quota should be 7453.2-8791.2 m3/hm2, the N and P2O5 fertilizers should be 185.8-284.1 and 74.6-116.9 kg/hm2. By calculating the ratio of target yield and irrigation quota, the water production efficiency for target yield of 5000-6500, 6500-8000, and 8000-9500 kg/hm2 should be 2.10-2.25, 1.54-1.55, and 1.07-1.08, respectively. The results in 2013 and 2014 were used for verifying the optimal results. The results revealed that the yield and water production efficiency in 2013 and 2014 based on the combined treatments all fell in range of target yield and water production efficiency. In summary, the optimal schedule for treatments and yield is helpful in saving water and fertilizers and keeping yield for rice cultivated in aerobic soil with drip irrigation under plastic film.