Study On Yield Formation And Nitrogen Utilization Of Rice Under Different Soils Conditions

Nitrogen is one of the limiting factors during rice production.Rice flowering is a critical period for rice yield formation.The nitrogen uptake and distribution of rice after flowering is closely related to the nitrogen status of rice at heading stage,which is affected by soil type,nitrogen level and rice genotype.The experiment was carried out under two soils in 2007,sandy soil and clay soil,in order to investigate the response of these factors to the yield formation and nitrogen utilization of post-anthesis rice.The nitrogen application levels of 0,180,270,and 360 kg-hm"2 was settled by experiment named as N0,N1,N2,and N3,respectively.The four rice varieties were Nanjing 9108,Yangjing 4227,Zhendao 18 and Nanjing 46,using the equation model to construct a simulation model of nitrogen uptake,utilization and transport of rice under two soils,analyze and compare the relative importance of yield components,and evaluate the difference in nitrogen uptake and utilization efficiency under different nitrogen levels.It provides an effective variety for rice nitrogen fertilization and improves nitrogen use efficiency,which provides a new basis for determining the parameters of soil part in crop growth simulation model.Below are key research findings:1.The yields of different rice varieties with different nitrogen levels in different soils were analyzed.As the nitrogen level increased,the number of panicles and the number of grains per panicle increased,and the seed setting rate decreased.The 1000-grain weight is only significantly different between different varieties.Under different nitrogen levels,the yield of different varieties under yellow clay was higher than that of sandy loam,but the effect of sandy loam increased significantly compared with yellow clay;the number of panicles and seed setting rate of yellow clay was higher,and the number of grains per panicle was higher.Soil type has a significant impact on yield and yield components.Soil and nitrogen levels have an effect on yield,panicle number,and seed set rate,and soil and variety effects on seed set rate and interaction.2.The nitrogen uptake and utilization status of different rice varieties after flowering was analyzed.The nitrogen use efficiency decreased with the increase of nitrogen application rate,and the nitrogen agronomic efficiency was higher than that of yellow clay in sandy loam soil.Soil type had a significant effect on nitrogen agronomic efficiency.Nitrogen levels had significant effects on harvest index,grain production efficiency and nitrogen agronomic efficiency.Varieties had significant effects on nitrogen use efficiency,and soil and nitrogen levels were nitrogen.There is an interaction effect.3.The dynamics of nitrogen dynamics in different nitrogen types of rice with different soil types and different nitrogen levels were obtained by equation fitting.The SPAD values of the leaves of the top three leaves after rice emergence showed a slow and fast trend corresponding to the inverted logistic model,and the low leaf position.The leaf SPAD value decreased faster under sandy loam soil,and the flag leaf SPAD value decreased faster under clay.The dry matter weight,nitrogen uptake,nitrogen content and nitrogen partitioning index of the stems and sheaths of Nanjing 9108 were all open parabolic lines;the dry matter weight,nitrogen content and nitrogen distribution index of leaves were linear after time.The trend of decline,while the amount of nitrogen uptake after flowering decreased exponentially,the dry matter weight and nitrogen content decreased faster under yellow clay,and the nitrogen partition index decreased faster under sandy loam;grain dry matter weight,nitrogen uptake The amount and nitrogenpartitioning index showed a logistic growth curve trend,and yellow clay was beneficial to grain nitrogen accumulation and distribution.4.After analyzing the dynamic fitting parameters of SPAD value of rice flowering leaves,the results showed that the simulated parameters of the SPAD value of the leaves of Yangjing 4227,Zhendao 18 and Nanjing 46 were significantly negative.relationship.the results showed that the simulated parameters of the SPAD value of the leaves of Yangjing 4227,Zhendao 18 and Nanjing 46 were significantly negative relationship.