| Rice is an important food crop,which plays a vital role in ensuring national food security production.In actual production,there is excessive application of nitrogen fertilizer in rice.This not only has an impact on the environment,but also is very harmful to the sustainable development of rice cultivation.Organic fertilizer has little pollution to the environment.In recent years,more and more attention has been paid to it in rice production.Therefore,reducing the amount of nitrogen fertilizer and strengthening the application of organic fertilizer are of great significance for the sustainable development of rice.A randomized block experiment design was used in this study.The local conventional nitrogen application rate was used as the control,i.e.the application rate of pure nitrogen was 170 kg·hm-2,and the control was used as the standard to reduce the application rate of nitrogen by 10%,20%and 30%respectively,and the organic fertilizer 150kg·hm-2 was used as the three nitrogen reduction treatments.To study the effects of reducing the amount of nitrogen fertilizer and applying organic fertilizer on rice growth and development,accumulation and distribution of nitrogen,phosphorus and potassium,yield and its components,to explore the preliminary effect of reducing nitrogen and applying organic fertilizer in rice,and to screen out the best amount of reducing nitrogen and applying organic fertilizer,so as to provide the basis for rational fertilization of rice and lay the foundation for sustainable development of rice.The main results of this experiment are as follows:1.The plant height of Kenjiandao 6 and Kongyu 131 increased with the advance of growth period.At heading stage and maturity stage,the plant height of each treatment decreased with the decrease of nitrogen application.The plant height of N10 treatment was closer to CK than that of N20 and N30.The tiller number per hole of Kenjiandao 6 and Kongyu 131 increased first and then decreased with the advance of growth period.Under the treatment of N10,the tiller number and tiller rate of both varieties were the highest,and the tiller number of Kenjiandao 6 was more than that of Kongyu 131 at each growth stage.The leaf area of Kenjiandao 6 and Kongyu 131 increased first and then decreased with the advance of growth period.The leaf area of Kenjiandao 6decreased with the decrease of nitrogen application.The leaf area of Kenjiandao 6 was smaller than that of Kongyu 131.Leaf area index?LAI?of Kenjiandao 6 and Kongyu 131 increased first and then decreased with the advance of growth period,while LAI decreased gradually with the decrease of nitrogen application.Based on the analysis of plant height,tillering dynamics,single-hole leaf area and leaf area index,it was preliminarily concluded that 10%reduction of nitrogen fertilizer combined with 150kg·hm-2 organic fertilizer was basically the same as conventional fertilization,which was better than N20 and N30.2.At heading stage and maturity stage,the changing trends of stem-sheath weight,leaf weight and panicle weight of Kenjiandao 6 and Kongyu 131 were inconsistent.At heading stage,the proportion of stem-sheath was the largest,followed by leaves and panicles,and the proportion of panicles was the smallest.At maturity stage,after material accumulation and transportation,the accumulation in panicle reached the highest level,and the volume of stem-sheath material reached the highest level.The accumulation decreased and the leaves increased slightly.The results showed that the stem sheath weight,leaf weight and panicle weight decreased gradually with the decrease of nitrogen application.The stem and leaf material transport,stem and leaf material transport rate and stem and leaf material transport contribution rate of N10 treatment were higher than those of other treatments,and the contribution rate of stem and leaf material transport was significantly higher than that of CK treatment,the results showed that N10 treatment significantly improved the assimilation and translocation ability of stem and leaf substances in two rice varieties.3.With the decrease of nitrogen fertilizer application rate,the nitrogen content and nitrogen accumulation in rice decreased gradually,and the agronomic use efficiency,partial productivity and uptake efficiency of nitrogen in Kenjiandao 6 and Kongyu 131 rice varieties also decreased gradually.Nitrogen content and nitrogen accumulation in stem sheath,leaf and grain were the highest in N10,close to CK,and significantly higher than those in other treatments.With the application of organic fertilizer,the partial productivity of rice has been significantly improved.The nitrogen utilization efficiency and absorption efficiency of N10 treatment are significantly higher than those of N20 and N30.With the decrease of nitrogen application,the nitrogen absorption efficiency of rice gradually decreases.The application of organic fertilizer increased the accumulation of phosphorus in stem sheath,leaf and grain,and with the decrease of nitrogen application,the accumulation of phosphorus did not decrease significantly.Potassium accumulation decreases with the decrease of nitrogen application rate,but organic fertilizer did not increase potassium accumulation.4.Nitrogen reduction combined with organic fertilizer had significant effects on Yield and its components of two varieties of rice.The panicle number,grain number per panicle,seed setting rate,1000-grain weight,theoretical yield and actual yield of Kenjiandao 6 and Kongyu 131 rice varieties varied with the decrease of nitrogen application.The 1000-grain weight of two rice varieties is the main factor affecting rice yield.Reducing the amount of chemical fertilizer and applying organic fertilizer affect the formation of 1000-grain weight mainly by affecting the accumulation of nitrogen in the grain,which is ultimately reflected in the change of yield.5.With the decrease of nitrogen fertilizer application,the more nitrogen fertilizer is saved,the yield decreases and the benefit decreases gradually.The best benefit is the combination of 10%nitrogen fertilizer reduction and organic fertilizer application.However,blindly reducing the application of chemical fertilizers has not effectively compensated for the resulting nitrogen deficit.Although the cost of nitrogen fertilizer has been saved,the ultimate reduction in yield is irreparable. |
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