Effects Of Nitrogen Fertilizer On Nitrogen Metabolic Enzyme Activity And Nitrogen Utilization In Rice

Food security is closely related to the rational application of nitrogen fertilizer,so it is very important to improve the absorption and utilization of nitrogen by rice itself to reduce the application of nitrogen fertilizer.Therefore,the effects of nitrogen on nitrogen metabolic enzyme activity and nitrogen utilization in different rice varietiess were studied.It can provide a basis for further study on the mechanism of nitrogen distribution and regulation and the absorption and utilization of nitrogen by plants.In this paper,Liaoxing 1,Shendao 47,Shendao 6,Qiaorunjing 9 and Akitakomachi were used as the experimental materials.Four nitrogen fertilizer levels,no nitrogen(0 kg/hm2),low nitrogen(120 kg/hm2),medium nitrogen(180 kg/hm2)and high nitrogen(240 kg/hm2),were set up in field experiments.The main results were shown as follows:Nitrogen fertilizer application could significantly increase the yield of different rice varieties,and the yield increased with the increase of nitrogen application.The yield of Akitakomachi was significantly lower than that of other varieties.The grain number per panicle increased with the increase of nitrogen fertilizer application in a certain range,and the seed setting rate and 1000-grain weight decreased with the increase of nitrogen application.The correlation analysis showed that yield was significant or extremely significant positive correlated with grain number per panicle,primary branches,secondary branches,primary branch grains,secondary branch grains,spikelet number per unit area and sink capacity.Nitrogen application increased the activity of nitrogen metabolic enzymes.The activities of NR and GOGAT were the highest at tillering stage and lowest at maturity stage.GS showed highest activity at heading stage and lowest at maturity stage.The correlation analysis showed that there was a significant or extremely significant correlation between GS and yield at all investigated growth stages.Nitrogen accumulation in different growth stages showed an overall upward trend with the increase of nitrogen application.The agronomic utilization efficiency and absorption utilization efficiency of nitrogen fertilizer increased with the increase of nitrogen application,while partial productivity and harvest index of nitrogen fertilizer decreased with the increase of nitrogen application.Under different nitrogen fertilizer treatments,the agronomic utilization efficiency of Liaoxing 1 and Shendao 47 were significantly higher than that of Qiaorunjing 9 and Akitakomachi.The uptake and utilization efficiency of Shen-Dao 47 was significantly higher than that of Akitakomachi,and the partial productivity of nitrogen fertilizer in Akitakomachi was significantly lower than that of other varieties.The correlation analysis exhibited that nitrogen accumulation was extremely significant positive correlated with NR activity at tillering stage,nitrogen accumulation was significantpositive correlated with GS activity at different growth stages,nitrogen accumulation was significant positive correlation with GOGAT activity at tillering stage.Nitrogen fertilizer absorption and utilization rate was extremely significant positive correlation with GS activity at heading stage,nitrogen fertilizer absorption and utilization rate was significant positive correlation with GOGAT activity at tillering stage.Nitrogen accumulation was extremely significant positive correlation with yield and nitrogen fertilizer uptake and utilization rate.Nitrogen accumulation was extremely significant positive correlation with nitrogen fertilizer agronomic utilization rate at heading stage and maturity stage.Nitrogen accumulation was extremely significant positive correlation with nitrogen fertilizer agronomic utilization rate at grain filling stage.The yield was extremely significant positive correlation with the agronomic and absorption utilization efficiency of nitrogen fertilizer.