Effects Of Nitrogen And Planting Density Coupling On Yield And Quality Of Rice

Rice is one of the important grain crops in China.Strong individual and suitable population structure are the important guarantee for high yield and good quality of rice.In this experiment,Wuyoudao No.4(Daohuaxiang No.2)was used as the experimental material.The density was the main area(D1 and D2 were 18 and 25 hills per meter square,respectively),and the nitrogen application rate was the secondary area(N0,N1,N2 and N3 were 0,75,105,135 kg N/hm~2,respectively).A field plot experiment was conducted to study the effects of nitrogen application rate and planting density on the yield and quality of rice by measuring the absorption and utilization of nitrogen,tillering characteristics,yield and quality of rice and other indicators.The aim of this experiment is to provide theoretical basis for scientific and rational fertilization of rice to improve the yield and quality of rice in cold region.The Results are as follows:With the increase of N fertilizer,tillers and dry matter of rice increased first,and then decreased when the N fertilizer reached 105 kg/hm~2.When the amount of nitrogen application was the same,the tillers and dry weight per hill of sparse planting were higher.When the density was higher,although the tillers and dry weight per hill were lower,the deficiency of tillers and dry weight per hill could be made up by increasing the population.The amount of nitrogen fertilizer and planting density had a significant effect on the number of tillers at each leaf age stage.The occurrence of tillers mainly occurred at 6-10 leaf stage,accounting for more than 60%of the total.Tillers at 8-10leaf stage were most affected by nitrogen application.The yield of rice first increased with the application of nitrogen fertilizer,and then decreased when nitrogen rate reached 105 kg/hm~2.Compared with sparse planting,dense planting was more beneficial to increase yield,with an average increase of 11.4%.Applying nitrogen fertilizer could increase the number of panicles and grains per panicle,decrease the seed setting rate and 1000-grain weight.And the density increased followed by the increase of the number of panicles and seed setting rate.The yield of rice mainly came from tillers before 8-leaf stage,which accounted for more than 70%of the total yield.The yield of tillers at 8-10 leaf stage increased first and then decreased with the increase of fertilizer application.Sparse planting could increase the proportion of yield at this leaf age stage.Nitrogen fertilizer and sparse planting have the effect of increasing the number of ear-bearing tillers at each stage,and the influence degree increased gradually with the increase of leaf age;the number of ear-bearing tillers at this leaf age stage accounted for more than 60%of the total number of panicles at 6-10 leaf stage,which was the most important leaf age stage to increase the number of panicles.With the increase of leaf age,1000-grain weight decreased after tillering and ear-forming.Excessive nitrogen fertilizer had a negative effect on rice quality,and rational dense planting was benefical to improve rice quality.The milling quality was mainly affected by nitrogen fertilizer.Compared with N0,nitrogen fertilizer significantly improved the rice yield rate.Under dense planting conditions,the average brown rice rate,milled rice rate and head rice rate were decreased by 0.24%,0.41%and 1.50%,respectively.The ratio of length to width had little relation with nitrogen fertilizer and planting density.Nitrogen fertilizer increased chalky grain rate by 8.00%on average,and by 3.66%on average in dense planting.Nitrogen fertilizer and planting density have no significant effect on protein content,amylose content.The taste value of nitrogen fertilizer decreased by 4.00 on average,and that of dense planting increased by 1.5 on average.With the increase of nitrogen application rate,the content of ammonium nitrogen and nitrate nitrogen in grain increased significantly,and the difference between nitrogen treatment and N0treatment was significant(p<0.05).Sparse planting was conductive to increasing the nutrient content,and the ammonium nitrogen and nitrate nitrogen in grain increased by 1.04μg/g,37.55μg/g and 4.18μg/g,respectively.On the effect of nitrogen efficiency,nitrogen fertilizer and density have a significant effect.With the increase of nitrogen fertilizer rate,nitrogen efficiency would reduce.Under different density conditions,sparse planting can improve nitrogen absorption and utilization rate and agronomic efficiency,dense planting can improve the nitrogen physiological utilization rate and the nitrogen partial factor productivity.In a word,increasing planting density can achieve high yield of rice,while too much nitrogen is harmful for high yield and good quality of rice.From the perspective of coordinating rice yield and rice quality,the amount of nitrogen fertilizer at 105 kg/hm~2 is suitable,which can achieve high yield and good quality of rice.