Effects Of Soil Fertility Conditions And Nitrogen Application Rate On Nitrogen Use Efficiency,yield And Quality Of Indica Rice

Rice is one of the most important food crops in China.Nitrogen fertilizer plays an important role in the growth,development,high and stable yield of rice.With the development of modern agriculture and the improvement of people’s living standards,rice quality has attracted more and more attention.The quality of rice is affected by the genetic characteristics of varieties,cultivation techniques,soil fertility and so on.In order to explore the effects of soil fertility conditions and nitrogen application rate on nitrogen use efficiency,yield and quality of indica rice,the purpose is to provide theoretical basis and technical guidance for rational fertilization and yield increase in rice production under different soil fertility conditions.In order to explore the effects of soil fertility conditions and nitrogen application rate on nitrogen use efficiency,yield and quality of indica rice,and to provide theoretical basis and technical guidance for rational fertilization and yield increase in rice production under different soil fertility conditions.The field experiment was conducted in Jiuzhou Town,Huangping County,Guizhou Province from 2020 to 2021.With Qyou6(V1),Yixiangyou2115(V2),nei5you5399(V3)and Huang huazhan(V4)as materials,the experiment adopts split plot design,with two factors of soil fertility(S)and nitrogen application rate(N),the treatment of the main area is n and the sub area is V,with four levels of soil fertility(high,high,medium and low)and four levels of nitrogen application rate(0,75,150 and 225 kg/ha).The main results are as follows:(1)Effects of soil fertility conditions and nitrogen application rate on yield of Indica RiceThe rice yield decreases with the decrease of soil fertility conditions,and there is a significant quadratic regression equation between the yield of indica rice and the amount of nitrogen application under different soil fertility conditions.According to the regression equation,from 2020 to 2021,the average values of the highest yield of rice under high,high,medium and low soil fertility conditions are 9931.26,10185.89,9800.10 and 9757.71 kg/ha,respectively;and the corresponding average suitable nitrogen application rates are 113.04,161.90,159.78 and 147.87 kg/ha,respectively.High fertility paddy soil is more conducive to nitrogen efficiency.Compared with other soil fertility conditions,it requires less nitrogen application to achieve the maximum yield.In actual production,appropriate target yield and nitrogen application rate should be formulated according to the actual situation of paddy soil fertility,or the increase of rice yield should be promoted by fertilizing soil fertility.(2)Effects of soil fertility conditions and nitrogen application rate on dry matter accumulation of Indica RiceThe improvement of soil fertility conditions is conducive to the increase of post panicle proportion,dry matter accumulation before panicle and maturity of indica rice,while the harvest index decreases.The dry matter accumulation of indica rice before panicle and at maturity increased with the increase of nitrogen fertilizer,but the harvest index was opposite.There are significant differences in dry matter accumulation of Indica Rice under different soil fertility conditions.The overall performance is high soil fertility > high soil fertility > medium soil fertility > low soil fertility.In terms of dry matter accumulation of rice,rice under high soil fertility has certain advantages.Therefore,in rice cultivation,we should consider the actual situation of soil fertility,carry out reasonable fertilization and pay attention to the fertilization of medium and low yield fields,so as to achieve high yield and high efficiency.In this study,compared with Conventional Indica rice,hybrid indica rice also has certain advantages in dry matter accumulation and transportation.(3)Effects of soil fertility conditions and nitrogen application rate on nitrogen use efficiency of Indica RiceAt different soil fertility levels,with the increase of nitrogen application rate,nitrogen harvest index,nitrogen rice productivity and nitrogen physiological utilization rate showed a downward trend.The overall performance of nitrogen physiological utilization rate and nitrogen absorption and utilization rate was high soil fertility > medium soil fertility > low soil fertility.In addition,there were significant differences in nitrogen use efficiency among different rice varieties.Compared with the other three varieties,V4 had the highest nitrogen physiological use efficiency.Therefore,in the actual production of rice,fertilization should be carried out according to different soil fertility conditions and variety characteristics in order to achieve high nitrogen efficiency.(4)Effects of soil fertility conditions and nitrogen application rate on rice quality of Indica RiceWith the decrease of soil fertility conditions,the rate of brown rice,milled rice,whole milled rice,gel consistency and crude protein content decreased,while the change trend of amylose content was opposite.The chalky grain rate and chalkiness degree showed high soil fertility > high soil fertility > medium soil fertility > low soil fertility.Except in M condition,the brown rice rate,milled rice rate and whole milled rice rate showed an increasing trend with the increase of nitrogen application.The crude protein content increased linearly with the increase of nitrogen application,while the change trend of chalky grain rate was opposite.The gel consistency had no obvious change trend with the increase of nitrogen application rate and soil fertility conditions.(5)Relationship between yield and dry matter and nitrogen use efficiency of Indica RiceCorrelation analysis showed that the two-year rice yield was significantly positively correlated with the dry matter accumulation at heading stage and maturity stage,but negatively correlated with the harvest index.In addition to the positive correlation with nitrogen physiological utilization rate,the correlation between rice yield and other indicators of nitrogen utilization rate was significantly different between years.From the comprehensive analysis of rice yield,quality and nitrogen use efficiency,the rice field under high fertility condition only needs low amount of nitrogen fertilizer to improve the yield and nitrogen use efficiency of indica rice,and has a certain optimization effect on the appearance quality and cooking nutritional quality of rice,while the medium and low fertility rice field can not reach the level of rice field under high fertility condition even under high nitrogen treatment.The level of soil fertility conditions has a significant impact on rice yield,nitrogen utilization rate and yield.In the actual cultivation of indica rice,we should strengthen the cultivation of medium and low soil fertility paddy field fertility,so as to achieve the goal of high yield,high quality and high efficiency.