Effects Of Nitrogen Fertilizer Management And Plant Allocation On Yield Formation And Stress Resistance Of Double-cropping Super Rice In South Hunan

Hengyang,Hunan is an important rice producing area in China,which plays an important role in ensuring food safety.However,rice production in this region has many problems,such as excessive application of nitrogen fertilizer and unreasonable distribution,high risk of lodging,and frequent disasters.In recent years,the area planted with super rice has gradually expanded.In order to improve the high-yield and stable-growing cultivation techniques for double-cropping super rice in southern Hunan,the effects of nitrogen fertilizer management and plant configuration on yield formation and the inverse resistance of double-cropping super rice in southern Hunan,were studied by setting 4 kinds of nitrogen fertilizer management methods(proportion of basal N: tillering N: panicle N: grain N,4:3:2:1,N1;5:3:1:1,N2;6:3:1:0,N3;7:3:0:0,N4)and 2 plant and row spacing(16.7cm×16.7cm,16.7cm×20.0cm),and 3 basic seedlings(2,4,6 plant/hill).The main results are as follows:(1)Nitrogen fertilizer management methods affected dry matter accumulation of late rice,nitrogen fertilizer for panicles and grains was important to heighten total dry matter weight to provide the basis for high yield of rice.(2)The nitrogen fertilizer operation method significantly affected the yield of early and late rice.The highest yield of N1 treatment was 9467.77 kg/ha,and that of late rice was 8864.21 kg/ha.The treatment of N2 was the second,and the yield of N4 and N3 treatment was lower.The use of a certain amount of nitrogen fertilizer as a granular fertilizer can effectively increase the yield of double-season rice in southern Hunan.(3)Nitrogen fertilizer management methods significantly affected lodging tolerance of rice.The bigger N proportion in former stages led to lower lodging-resistance capacity,namely higher lodging index,while nitrogen fertilizer back shift could improve lodging-resistance capacity.(4)Nitrogen fertilizer management methods significantly affected the activity of protective enzyme and MDA content.In different treatments,N1 and N2 had higher activity of POD and SOD,and lower content of MDA,namely which had stronger inverse resistance.(5)Plant configuration has a significant effect on the dry matter accumulation of rice,but the response of rice in early and late rice is different.From the perspective of improving dry matter accumulation in mature stage,X1 plant spacing(16.7cm × 16.7cm)and 4-6 basic seedlings per hill should be adopted for early rice,and late rice should use X2 plant spacing(16.7cm × 20.0cm),2-4 basic seedlings per hill.(6)Plant configuration modes significantly affected the yield and yield components of rice.Early rice could gain higher yield by more basic seedlings while late rice could gain higher yield by less basic seedlings.So insurance of more basic seedlings was important for early rice.(7)Plant configuration modes affected stem thick and lodging index.In common,bigger plant and row spacing and less basic seedlings deduced to bigger stem thick and smaller lodging index.(8)Plant configuration modes significantly affected the activity of protective enzyme and MDA content.The bigger plant and row spacing and less basic seedlings were advantageous to improve activity of POD and SOD,and reduce the content of MDA.These results indicated that considering improvement of yield and inverse resistance of double-cropping super rice in southern Hunan,the optimal nitrogen fertilizer management method and plant configuration mode must be adopted.The optimal nitrogen fertilizer management methods for early and late rice were 4:3:2:1 and 5:3:1:1,the optimal plant and row spacing and basic seedlings for early rice were 16.7 cm×16.7 cm and 4 seedlings per hill,and those for late rice were 16.7 cm×20 cm and 2 seedlings per hill.