Effects Of Nitrogen Fertilizer And Configuration Of Planting Density And Seedlings On Yield And Quality In High-Quality Late Japonica Rice Changjing 225

Rice is one of the main food crops in China,which is related to food security and people’s livelihood.The double cropping late rice in Jiangxi is vulnerable to "cold dew wind" at booting stage,heading stage,flowering stage and filling stage,which seriously affects the normal process of rice flowering,pollination and filling,resulting in serious yield reduction.Compared with indica rice,japonica rice was cold-resistant and could effectively resist the adverse effects of "cold dew wind".Changjing 225 is a high-quality late japonica rice variety independently bred by Jiangxi Agricultural University.It combines the advantages of low temperature resistance,lodging resistance,high economic coefficient of japonica rice and early growth and high temperature resistance of indica rice.In this study,high-quality late japonica rice Changjing 225 and Exiang 2(control)were used as experimental materials,and experiments of different nitrogen dosage and planting density and basic seedling configuration were set up,in order to explore the influence of nitrogen dosage,planting density and basic seedling configuration on the yield and quality formation and nitrogen fertilizer absorption and utilization ratio of Changjing 225.It provides theoretical and practical basis for high yield,high quality and efficient cultivation of Changjing 225.The main results are as follows:1.Nitrogen level,planting density and the combination of basic seedlings have significant effects on the yield of Changjing 225.The yield increased first and then decreased with the increase of nitrogen application rate.When the nitrogen application rate was below 210 kg/hm2,the yield increased with the increase of nitrogen application rate,while when the nitrogen application rate was above 210 kg/hm2,the yield began to decrease.In the control group,the yield of E Xiang 2 increased with the increase of nitrogen application rate when the nitrogen application rate was less than 210 kg/hm2,while the yield began to decrease when the nitrogen application rate was higher than 210 kg/hm2.Suitable sparse planting is conducive to the increase of yield of Changjing 225.Under the conditions of this experiment,the density and the combination of basic seedlings is D2S1(25 cm X 18 cm,3 seedlings/hole),and the yield is the highest.With the increase of nitrogen application rate,the effective panicle number,grains per panicle and dry matter accumulation of Changjing 225 increased.However,when n application rate is higher than 210 kg/hm2,the effective panicle number and dry matter accumulation of Changjing 225 do not increase or even decrease,the number of grains per panicle decreases,and the harvest index decreases.Compared with the treatment with low density(25 cm X 18 cm)and high seedling number(7 seedling/hole),the treatment with high density(25 cm X 14 cm)and low seedling number(3 seedling/hole)increased the effective panicle number and 1000-seed weight,dry matter accumulation and apparent conversion.2.With the increase of nitrogen application rate,the N accumulation of Changjing 225 increases,and the N absorption and utilization ratio,N agronomic efficiency,N partial productivity,N physiological utilization ratio,N intrinsic nutrient efficiency and N harvest index all decrease.However,with the increase of planting density,nitrogen accumulation increased,nitrogen absorption and utilization rate,nitrogen agronomic efficiency,partial nitrogen productivity and nitrogen physiological utilization rate increased.3.Nitrogen application rate had significant effects on rice quality and starch viscosity of Changjing 225.With the increase of nitrogen application rate,the processing quality and nutritional quality of rice were improved,and the appearance quality was improved first and then deteriorated,but the cooking and cooking taste quality and starch viscosity characteristics were deteriorated,and the taste value decreased significantly.Therefore,the optimal nitrogen density combination of Changjing 225 in this experiment is 210 kg/hm2 pure nitrogen and D2S1(25 cm × 18 cm,3 seedlings/hole).