SHALLOW WET IRRIGATION INCREASES IRRIGATION WATER USE EFFICIENCY WHILE MAINTAINING PADDY RICE YIELD-A STUDY BASED ON ENTROPY WEIGHT COEFFICIENT MODEL

The comprehensive benefit evaluation of water-saving irrigation has important guiding significance for the scientific irrigation of paddy rice and the improvement of water use efficiency. In this study, three different irrigation modes including shallow wet irrigation, rain-used shallow wet irrigation (rain-used irrigation) and conventional irrigationwere adopted, and the entropy weight coefficient evaluation model was introduced for optimal selection of the irrigation scheme. Taking rice yield, irrigation water use efficiency and rice field leakage as the main indicators, the comprehensive benefits of water saving and yield increase in paddy rice fields under different irrigation modes were compared. The results showed that compared with conventional irrigation, shallow wet irrigation and rain-used irrigation could save 24.3% and 15.6% of irrigation water. The irrigation water use efficiency of rice under shallow wet irrigation, rain-used irrigation and conventional irrigation were 3.94, 3.68 and 3.54 kg/m(3) respectively. The irrigation water use efficiency of paddy rice under shallow wet irrigation was significantly higher than that under conventional irrigation (p<0.05), but there was no significant difference in rice yield and its components (total panicle grain weight, average panicle length, average panicle grain and seed setting grain number) among thethree different irrigation treatments (p>0.05). For thethree treatments, the evaluation value of entropy weight coefficient of shallow wet irrigation was the highest, reaching 0.98, indicating that the comprehensive benefit of shallow wet irrigation was the optimal. The conclusions can provide theoretical and practical basis for the selection of water-saving irrigation regime for those rice planting areas.