Effects Of Densification And Nitrogen Reduction On Rice Yield And Rice Eating Quality

The yield and quality of rice are affected by cultivation measures,and nitrogen fertilizer management and planting density have important effects on rice yield and quality.Although increasing nitrogen fertilizer is beneficial to the high yield of rice,it affects the eating quality,and reducing nitrogen will reduce the yield.Therefore,it is of great significance to study the densification and nitrogen reduction for the coordination of rice yield and eating quality.In this study,two high-quality rice varieties,E zhong 5and E xiang 2,were selected,and three planting densities were set(D1 370,500holes.hm^-2,D2 303,000 holes.hm^-2,D3 256,500 holes.hm^-2)and 8 nitrogen fertilizer management treatments CK（no nitrogen application）,50A(50 kg.hm^-2 nitrogen application level,the ratio of base and tiller fertilizer is 7:3),50B(50 kg.hm^-2 nitrogen application level,base,tiller fertilizer ratio is 7:3),ear fertilizer ratio is 5:3:2),100A(100 kg.hm^-2 nitrogen application level,base and tiller fertilizer ratio is 7:3),100B(100kg.hm^-2 nitrogen application level,base,tiller,ear Fertilizer ratio is 5:3:2),100C(100kg.hm^-2 nitrogen application level,basal,tiller,ear fertilizer ratio is 4:2:4),200A(200kg.hm^-2 nitrogen application level,basal,tiller fertilizer ratio is 5:3:2)The fertilizer ratio is 7:3),200B(200 kg.hm^-2 nitrogen application level,the base,tiller,and panicle fertilizer ratio is 5:3:2),focusing on the synergy of high quality and high yield of rice under different nitrogen fertilizer management and planting density treatments Growing plant type and population characteristics and their effects on yield and eating quality.The main results are as follows:（1）The increase of planting density and the decrease of nitrogen application level made the overall plant and panicle type more compact,which in turn affected the population quality of rice.The increase of planting density decreased tiller angle,panicle length,panicle neck thickness,branch number by 4.79～13.2%,0.05～4.61%,2.17～6.00%,0.21～7.94%,2.97～18.76%,respectively.With the decrease of nitrogen application level,the plant height,internode length,leaf base angle,panicle length,secondary branch number all decreased significantly,and the decrease rates were 0.6～9.95%,1.04～32.20%,0.70～26.51%,respectively,0.55～3.57%,0.34～15.24%.With the advance of nitrogen fertilizer,the panicle neck thickness,secondary branch number of the two varieties decreased by 0.47～5.07%,2.35～9.12%,respectively,while the number of primary branches decreased with nitrogen fertilizer.It moved forward and rose,with an increase of 0.63～5.78%.The increase of planting density and the advance of nitrogen fertilizer had significant effects on leaf SPAD value,the high efficient leaf area index,interception radiation percentage and population biomass of the two varieties,and the reduction of nitrogen application level significantly decreased the above indexes of the two varieties,and the reduction of nitrogen application level made the above indexes of the two varieties decrease significantly,the decrease rate was 0.50～37.93%,9.58～42.91%,1.43～12.04%,4.34～36.98%respectively.（2）The increase of planting density significantly increased the yield of the two varieties,while the decrease of nitrogen application level and the advance of nitrogen fertilizer significantly decreased the yield of the two varieties.The increase of the panicle number of the two varieties is the main factor to increase the yield of the two varieties.The panicle number and yield increase are 3.22～25.99%and 1.99～13.47%respectively.Nitrogen reduction reduces the yield and yield component factors of the two varieties,thereby reducing the The yield was decreased by 10.08～28.67%;the advance of nitrogen fertilizer significantly reduced the number of spikelets per panicle,filled grains and thousand grain weight of the two varieties,thereby reducing the yield by 0.25～4.86%,0.66～7.36%,1.52～3.46%,2.81～10.75%.（3）The increase of planting density,the decrease of nitrogen application level,and the advance of nitrogen fertilizer significantly reduced the protein content of the two varieties of rice,and significantly improved the taste value of the two varieties.The increase of planting density decreased the protein content of the two varieties of rice,and both achieved the minimum or smaller value at D1,and the taste value showed an upward trend,and both achieved the maximum or larger value at D1.With the reduction of nitrogen application level,the protein content of the two rice varieties decreased significantly,ranging from 7.24%to 30.84%,and the taste value increased significantly,ranging from 3.28%to 13.98%.With the advance of nitrogen fertilizer,the protein content of the two varieties of rice decreased significantly,with a decrease of2.93～15.21%,and the taste value increased significantly,with an increase of1.46～6.90%.（4）Correlation analysis showed that most of the plant morphological characteristics of the two cultivars were significantly positively correlated with high efficient leaf area index,interception radiation percentage and biomass,while stem wall thickness was significantly negatively correlated with interception radiation percentage.There was a significant correlation between the protein content and taste value of the two varieties of rice,and the morphological characteristics and population indicators of rice plants.The protein content of the two cultivars was positively or significantly positively correlated with plant height,the 4^th internode from the top to basal,the stem roughness,leaf SPAD value,stem+sheath biomass,leaf biomass,total biomass and yield,while the taste value was associated with On the contrary,there is a negative or significant negative correlation.In addition,the protein content of E zhong No.5 was also significantly positively correlated with the 1^st internode from the top to basal,the the 1^st leaf base angle from the top to basal,the interception radiation percentage and the high efficient leaf area index,while the taste value was the opposite,showing a significant negative correlation.To sum up,under the nitrogen application level of 100kg.hm^-2,basal fertilizer:tiller fertilizer=7:3,and 370,500 holes.hm^-2 planting density,the two varieties can obtain better plant morphological characteristics,population quality,yield and Food quality.