Effects of Different Paddy Field Drainage Degrees and Panicle Nitrogen Fertilizer Managements on Photosynthetic Productivity and Nitrogen Utilization of Rice under Triangle-Planted System of Rice Intensification

Abstract

The effects of different paddy field drainage degrees including three soil water content levels(0-20 cm soil relative water content was controlled at 80%±5%,60%±5%,and 40%±5%,named W 1,W 2,and W 3 respectively) and three panicle nitrogen fertilizer managements(the first panicle nitrogen fertilizer was applied on the 1st,8th,and 15th days after rewatering,named S 1,S 2,and S 3,respectively) on photosynthetic productivity during filling stage and nitrogen utilization of rice were investigated using medium hybrid rice Ⅱ you 498 under triangle-planted system of rice intensification(TSRI).The results showed that there was an obvious interaction to photosynthetic productivity,dry matter accumulation and nitrogen uptake,translocation and utilization between paddy field drainage degree and panicle nitrogen fertilizer management.Paddy field drainage had the most significant effect compared with panicle nitrogen fertilizer management.Canopy apparent photosynthetic rate at 15 days and 30 days and effective panicle number were decreased,under the treatment of applying the first panicle nitrogen fertilizer on the 1st day after rewatering,and canopy apparent photosynthetic rate at 15 days and 30 days after heading,harvest index and N production efficiency were increased under the treatment of applying the first panicle nitrogen fertilizer on the 8th or 15th day after rewatering in lower paddy field drainage condition(W 1).The treatment with higher paddy field drainage condition(W 2,W 3) applying the first panicle nitrogen fertilizer on the 1st or 8th days after rewatering was favorable to improve flag leaf photosynthetic rate at booting and full heading stages,canopy apparent photosynthetic rate at 15 days and 30 days after heading,dry matter accumulation,grain yield and its components,and nitrogen accumulation and utilization.From the comprehensive analysis and comparison,W 2 S 1 is the optimum combination for moderate paddy field drainage degree and panicle nitrogen fertilizer management under theTSRI,and its grain yield reached 10.96 t ha-1.