Effects Of Nitrogen Application Rate On Yield And Quality Of High-quality Rice

The consumption of high quality rice has increased due to higher living standards.To meet the demand,the development of high-quality rice become the main direction of the rice industry.Fertilization is a basic technology in rice production,which affects both rice yield and quality;nitrogen application amount has become a key technology in the production of high-quality rice.Field experiments were conducted with six hybrid rice and conventional rice varieties at Yangtze University in Jianghan Plain.The experiments were designed as split plot with nitrogen treatments(N1:105 kg N/hm~2,N2:135 kg N/hm~2,N3:165 kg N/hm~2,N4:195 kg N/hm~2 and N5:225 kg N/hm~2)as the main plots and cultivars as the subplots.cultivar Grain yield and quality cultivarsare measured and compared across nitrogen treatments and cultivars,trying to find the best nitrogen application rate that balance yield with quality.The objectives are to provide the basis for the cultivation techniques of high-quality rice production.The main results are as follows.1.The yield and yield performance of each high-quality rice cultivar under different nitrogen application rates were different.Among them,the yield of three cultivars reached9.5-10.3t/hm~2,and the cultivarsrest reached 6.8-9.0t/hm~2.The relationship between yield/yield components and nitrogen treatments cultivars is expressed as an inverted-U function(highest yields under N2 and N3 treatments).The seed-setting rate and 1000-grain weight were the highest under N1 and N2 treatments,and the number of grains per panicle and effective panicle number were the highest under N2 and N3 treatments,with significant differences among different treatments(p<0.01).2.The processing quality,appearance quality,cooking and eating quality and nutritional quality of each high-quality rice cultivar varies across nitrogen treatments.In terms of processing quality,the brown rice rate,milled rice rate and whole milled rice rate of most cultivars were the highest under N2 treatment with the increase of nitrogen application rate,but there was no significant difference between N1 and N2.The whole rice rate of Xiangyaxiangzhan and Yexiang Youlisi reached the maximum value under N4and N5 treatments;in terms of appearance quality,the chalky grain rate and chalkiness of each cultivar showed a first decrease and then an increase with the increase of nitrogen application rate The trend was the lowest under N2 treatment;in terms of cooking and eating quality,the amylose content showed a trend of first decreasing and then increasing with the increase of nitrogen application rate,and N2 and N3 treatments were the lowest,and the peak viscosity and disintegration value increased with nitrogen application rate.The increase showed a trend of first increase and then decrease.The N2 and N3 treatments were the highest,the alkalinity value increased with the increase of nitrogen application rate,and the N1 and N2 treatments were the lowest;However,there was no significant difference among the treatments.The glutenin increased first and then decreased with the increase of nitrogen application.The N1 and N2 treatments were significantly lower than the other treatments.3.The accumulation of dry matter,nitrogen content of shoot organs and total nitrogen accumulation of each high-quality rice cultivar were different under different nitrogen application rates.With the increase of nitrogen application rate,the dry matter accumulation of each cultivar was the largest under N2 and N3 treatments;the nitrogen content of stem sheath,leaf and ear under N1 and N2 treatments were significantly higher than other treatments;The effect on the total nitrogen accumulation of plants varies with cultivars.Ezhong No.5,Jianzhen No.2,Ivory Xiangzhan and Yexiang Youlisi were significantly higher than other treatments in N3 and N4 treatments(p<0.05).Taiyou Exiangsimiao and Taoyouxiangzhan showed a trend of first increase and then decrease with the increase of nitrogen application,and the highest values were obtained under N2and N3 treatments.In conclusion,grain yield,quality,dry matter accumulation and nitrogen content of shoot organs of high-quality rice cultivars were significantly affected by different nitrogen application rates.After comprehensively weighing the effects of various nitrogen application treatments on high-quality yield and quality,the optimal nitrogen application rate suitable for high-quality rice production in this region was N2-N3 treatment(135-165kg N/hm~2).