Effects Of Multiple Cropping Model On Yield Formation And Nitrogenous Fertilizer Utilization Of Rice

In order to clear the effect of multiple cropping models on yield,dry matter production and nitrogenous fertilizer utilization of rice,a field experiment with three cropping systems(rice-rice-fallow,rice-rice-oilseed rape and rice-rice-green manure)and two planting patterns,tillage and machine planting(DY)and no-tillage and direct seeding(DYM),was conducted by using conventional indica rice variety“Zhongzao 39”in both early and late seasons and“Jinnongsimiao”in middle-season at three site(Yueyang,Changsha and Hengyang)in 2015-2016.The results showed that:(1)There were significant differences in yield of different treatments and sites.The ranking for yield among different sites was Hengyang>Yueyang>Changsha,and among different treatments was rice-rice-oilseed(DDY)>rice-rice-green(DDF)>rice-rice-fallow(DD)in early season,DDF>DDY>DD in late season.The annual yield of DDF and DDY showed 0.85 t/ha and 0.99 t/ha higher than DD.Meanwhile,the spikelets per m~2,total dry matter production and nitrogen assimilation of DDF and DDY were higher than DD.(2)The yield of rice in Hengyang was higher than Yueyang in both two years,0.83 t/ha in 2015 and 0.64 t/ha in 2016.The yield for tillage with machine planting(DY)was higher than the no-tillage with direct seeding(DYM)in both years,1.00 t/ha in 2015 and 1.08 t/ha in2016,respectively.The panicles per m~2 of DY is lower while the spikelets per panicle was higher than DYM;and the spikelets per m~2,harvest index,internal utilization efficiency of nitrogen and nitrogen harvest index of DY was higher than the DYM.(3)Double cropping rice has more advantages over middle-season rice on annual grain yield,within the same planting way,tillage and machine-transplanting;The annual grain yield of Double cropping rice were 7.46-7.87 t/ha higher in Hengyang and 5.25-6.6 t/ha higher in Yueyang.Annual grain yield of DDF or DDY is higher 0.27-0.41 t/hm2,1.28-1.35t/hm2 and 1.25-1.62 t/hm2 than DD at Hengyang,Yueyang and Changsha correspondingly;Gap of annual grain yield between Double cropping rice and middle-season rice is larger but smaller among different cropping systems at zhe higher grain yield level site.