Experimental Study On N Fertilizer Efficiency Of Three Super Ratoon Rice

For illustrating the nitrogen utilization and production increase effect,Super rice-ratoon rice Yiyou673,Ⅱ youming86 and lLiangyou616 were used to determine the dry matter accumulation and translocation,nitrogen uptake,yield and yield components were with different nitrogen rates in main-crop,results showed that:1.Nitrogen fertilizer has significant effects on population growth and dry matter accumulation.In the main-crop season,average leaf area index(MLAI)and crop growth rate(CGR)of N1,N2 and N3 were increased compared with the control N0,and the net assimilation rate(NAR)was lower than the control before the panicle initiation stage,and then higher than the control.In the range of experimental nitrogen rate,the dry matter accumulation of each organ increased with the increasing nitrogen fertilizer.In ratoon-crop season,before heading stage,Nl and N2 reduced MLAI of Yiyou673,N1 reduced MLAI of Ⅱ youming86,N1,N2,N3 reduced MLAI of Liangyou616.From heading stage to maturity,MLAI were increased,the largest was in N2.NAR and CGR increase first and then decline with nitrogen increasing,the largest was in N2 before heading stage and then in N1.Nitrogen application increased dry matter production,but the increasing extent was decline with nitrogen increasing.2.Nitrogen uptake was different at various stages.Transplanting to panicle initiation stage in main-crop season,main-rice maturity to ratoon-rice heading stage were highest nitrogen uptake rate and accumulating proportion,which took account for more than 60%of total plant nitrogen uptake.Nitrogen accumulation of main-crop increased with nitrogen fertilizer increasing,in ratoon-crop,it increased first and then decreased with increase nitrogen fertilizer,and three nitrogen application treatment were higher than N0.3.Nitrogen significantly increased yield of main-rice,the highest yield of yiyou673 and Ⅱ youming86 were obtained at N2 with liangyou616 at N1.In Ratoon-crop season,compared with N0,Yield of Yiyou673 and Ⅱ youming86 increased,the highest yield of Yiyou673 was in N1 and Ⅱ youming86 in N2;N1,N2 significantly increased yield of Liangyou616 while N3 significantly decreased yield.Nitrogen application increased panicle number and spikelets number per panicle,but had little effect on seed setting rate and 1000-grain weight.Regression analysis showed that the optimum nitrogen rate in main-crop season of Yiyou673,II youming86,Liangyou616 were 239.7kg·hm-2,231.17kg·hm-2,194.4kg·hm-2 respectively,which combination with 172.5 kg·hm-2 nitrogen application in ratoon-crop season can increase ratoon season yield to realize high production of main-and ratoon-rice.