Study On The Key Cultivation Strategies Of Late Japonica Rice In Double-cropping Rice Area

In this study, Zhendao 11 and Yongyou 2640 were used as materials, and by a series of tests, including interactions between methods of raising seedlings and seedling age,paclobutrazol, herbicide, nitrogen application, harvest time and moisture management, the effects of different measures on tiller emergency and grain plumpness oflate japonica rice in double-cropping rice area in Jiangxiwere studied, and the main research results were as follows:(1)At 25 days and 30 days after sowing, seedlings of late japonica rice in double-cropping rice area grew faster under the condition of the moist seedling raising and353 hole plastic floppy disk seedling, but with the 353 hole plastic floppy disk seedling,the late japonica rice tillering earlier after transplanting, and spike rate, effective panicles,grains per spike and yield were higher.(2) Under the condition of spraying with paclobutrazol at seedling stage, along with the increase of the concentration of paclobutrazol the leaf emergence rate of japonica hybrid rice increased, seedling height decreased, root length growth, the root numbers,tillering number per plant and the content of chlorophyll increased, tillering early after transplanting, the effective panicle number, spike rate, grain plumpness degree and the yield increased; the conventional Japonica Rice, the leaf emergence rate, root length, root number, tillering number per plant, chlorophyll content first increased and then decreased,the seedling height rose after the first drop, the effective panicle number, spike rate, grain plumpness degree and the yield first increased and then decreased.Seedling quality of conventional japonica rice and hybrid japonica rice were the best sprayed at 120 ~ 156mg/L, 156 ~ 192mg/L paclobutrazol respectively, tillering earlier after transplanting, spike rate were higher, the effective panicle number, spike rate, grain plumpness increased, and the yield were highest.(3) With the use of herbicides concentration increased, the effective tillers of hybrid japonica rice, the peak seedling number, spike rate, effective panicle number per plant,yield showed a slight decrease trend, but the difference was not significant; while the conventional japonica rice effective tiller number was significantly reduced, and ultimately effective panicle number was significantly reduced, the spike rate and yield slightly reduced. Overall, compared with japonica hybrid rice, the conventional japonica rice more sensitive to herbicides.(4) With the increase of nitrogen application rate, late japonica rice in double-cropping rice area tillering earlier, effective tiller number and effective panicle number increased, panicle rate reduced, grains per spike, total spikelets, grain plumpness and yield first increased and then decreased; at the level of fertilization 255kg·hm-2, withbasal nitrogen ratio increased, the double cropping late Japonica Rice tillering occurs earlier, effective tillers and effective panicles increased, spike rate first increased and then decreased, grains per spike, total spikelets, and yield first increased and then decreased.In different nitrogen treatments, conventional japonica rice and hybrid japonica rice in the 255kg·hm-2 nitrogen levels tiller earlier, more effective tillers, early-onset were highest,and the N accumulation, dry matter, source sink increment ratio from heading to maturity were the highest, spike rate, grains per spike, total spikelets per unit area and grain plumpness and 1000 grain weight were the highest, and the yield were highest.At the level of fertilization 255kg·hm-2, different application ratio of nitrogen treatment, conventional japonica rice and hybrid japonica rice in basal and tillering panicles tiller earlier at the percentage for 5:2:3 and 4:2:4 respectively, more effective tillers, early-onset were highest, source sink increment ratio from heading to maturity were the highest, the dry matter production, total amount of nitrogen uptake and nitrogen apparent productivity were highest, spike rate and total spikelets per unit area were highest,and can keep the higher seed setting rate and grain plumpness and grain weight, so the yield was highest.(5) Conventional japonica rice and hybrid japonica rice during 28 ~ 35 days, 28 ~ 42 days after heading respectively, as the cut-off time delayed, grain plumpness, 1000 grain weight and yield increased significantly, delay one day the yield were average increased37.1kg hm-2 and 42.1kg hm-2; as the cut-off time delayed, chalky rice rate and chalky whiteness gradually reduced, and roughness, milled rice rate, head milled rice rate and gel consistency overall showed increasing trend; for amylose content, the difference of conventional Japonica Rice in different water phase was not obvious, but hybrid japonica rice increasing gradually with the water phase delay.(6) Conventional japonica rice and hybrid japonica rice during 35 ~ 45 days, 35 ~ 50 days after heading respectively, with harvest time delayed, grain plumpness, 1000 grain weight and yield increased significantly, delay one day the yield average increased kg hm-2and 129.3 kg hm-2 respectively; with harvest time postponing, and chalky rice rate and chalky whiteness gradually reduced, but roughness, milled rice rate, head milled rice rate,straight chain starch and gel consistency overall showed increasing trend.