Effects Of Reduced Fertilization On Rice Growth,Yield And Nutrient Utilization

The applications of nitrogen,phosphorus,and potassium fertilizers are of great significance for increasing the yield and quality of rice and ensuring food security.However,the current excessive application of nitrogen,phosphorus,and potassium fertilizers in rice production has brought about a series of problems such as increased production costs,decreased nutrient utilization,and environmental pollution.Therefore,this paper studies the effect of reducing fertilizer application on rice growth,yield,and nutrient utilization,and provides a theoretical basis for reducing fertilization of rice.In 2019,a joint experiment was carried out in Xiangzhou County,Cenxi City,Gangbei District,Fumian District,and Longzhou County in Guangxi,setting up 5 treatments including T1 controlled plots,T2 full dose fertilizer application,T3 nitrogen deficient plots,T4 phosphorus deficient plots,and T5 potassium deficient plots.The dry matter and nutrient accumulation of rice,rice yield,and yield component factors are measured at the maturity stage.At the same time,using Baixiang 139,Guiyu 9(conventional rice),Y Liangyou 1,and Teyou 582(hybrid rice)as materials,joint experiments were carried out at three test sites in Guangxi Binyang County,Beiliu City,and Liucheng County.Three treatments of normal application of nitrogen and phosphorus fertilizers,50% reduction of nitrogen and phosphorus fertilizers,and no application of nitrogen and phosphorus fertilizers were set for each variety,and the dry matter and nutrient accumulation amount,rice yield,and yield component factors were measured at different periods.The main findings are as following:Under the condition of reducing the total amount of fertilizer,compared with the full fertilizer treatment,the rice yield of the nitrogen deficiency,phosphorus deficiency,potassium deficiency,and blank treatments were reduced by 10.42%-24.41%,2.02%-10.94%,-2.08%-12.21%,15.28%-50.89%,the average yield was reduced by17.61%,6.81%,5.05% and 26.25% respectively.Nitrogen fertilizer contributed highly to rice yield production,followed by potassium fertilizer and phosphorus fertilizer the least.The influence of fertilizers on yield components varies from fertilizer to fertilizer.Nitrogen fertilizer mainly affects the number of effective panicles and seed setting rate,phosphate fertilizer mainly affects the total number of grains per panicle,and potassium fertilizer mainly affected thousand-grain weight.Correlation analysis showed that under the condition of reducing the total amount of different types of fertilizers,rice yield was significantly positively correlated with the number of effective panicles and the total number of grains per panicle,and was correlated with seed setting rate and the thousand-grain weight Not obvious.Nitrogen,phosphorus,and potassium fertilizers significantly promote the accumulation of dry matter and nitrogen,phosphorus,and potassium uptake in rice.The accumulation of nitrogen,phosphorus,and potassium nutrients is greatly affected by the interaction between the environment and the treatment,while the accumulation of dry matter and the efficiency of nutrient production were affected by the interaction,however,the effect was minor.Under the condition of reduced nitrogen and phosphorus fertilizers,compared with the normal nitrogen and phosphorus fertilizer treatments,Baixiang 139,Guiyu 9,Y Liangyou 1,Teyou 582 early-season rice N and P fertilizers were reduced by 50% and no nitrogen and phosphorus fertilizers were applied.The treatment yields were reduced by-4.3%,7.0%;1.7%,8.4%;-9.4%,-0.2%;5.0%,6.0%.Its late-season rice output decreased by 3.0%,22.5%;5.7%,20.6%;3.8%,22.9%;1.6%,18.9%,respectively.Significant positivecorrelation was recorded under the condition of reducing nitrogen and phosphorus fertilizer among rice yield and effective panicle number,total grain number per panicle,seed setting rate,and thousand-grain weight.There was a significant negative correlation between the number of effective panicles and the total grains per panicle and thousand-grain weight;the total grains per panicle was significantly positively correlated with the thousand-grain weight with decrement in the amount of nitrogen and phosphorus fertilizers,the accumulation of nitrogen,phosphorus,and potassium in rice plants also decreases.However,the dry matter production efficiency of nitrogen,phosphorus,and potassium and the production efficiency of nitrogen,phosphorus,and potassium rice have increased,accordingly.Although the nitrogen and phosphorus fertilizers were reduced by 50%,nitrogen fertilizer,phosphorus partial productivity and the agronomic utilization rate of nitrogen and phosphorus fertilizers of rice were all higher than the normal application of nitrogen and phosphorus fertilizers.Different varieties have different responses to reduce nitrogen and phosphorus fertilizers.When the total amount of nitrogen and phosphate fertilizers is reduced,the difference in yield reduction of different varieties is very small.However,when the nitrogen and phosphate fertilizers are reduced by 50%,the yield of Baixiang 139 and Y Liangyou1 was less affected.Compared,with Guiyu 9 and Teyou 582,Baixiang139 and Y Liangyou 1 showed a smaller leaf area index and dry matter accumulation and a stronger nitrogen absorption capacity in the later stages of growth.In summary,the effect of applying nitrogen,phosphorus,and potassium fertilizers on increasing rice yield is nitrogen > phosphorus >potassium.Nitrogen fertilizer mainly affects the effective panicle number and seed setting rate,phosphate fertilizer mainly affects the total number of grains per panicle,and potassium fertilizer mainly affects the thousand-grain weight.Nitrogen,phosphorus,and potassium fertilizers significantly promoted the accumulation of dry matter and nitrogen,phosphorus,and potassium nutrients in rice.The characteristics of high-efficiency nitrogen and phosphorus utilization varieties are that the leaf area is relatively small,the number of effective panicles is relatively large,the total number of grains per panicle is moderate,and the accumulation of material and nitrogen in the later growth period is high.