Effects Of Organic Fertilizer Substitution And Transplanting Density On Nitrogen Utilization Characteristics,Yield And Quality Of Early Season Indica Rice

Reasonable planting density and scientific water and fertilizer management are the key factors to achieve high yield and improve resource utilization efficiency of rice.Nitrogen fertilizer is an important nutrient for rice growth,but in recent years,the large-scale application of nitrogen fertilizer has not only caused the waste of resources but also caused environmental pollution.Organic fertilizer is rich in organic matter and effective nutrients,which can provide nutrients for rice growth.The use of organic fertilizer instead of chemical fertilizer can reduce a series of environmental problems caused by excessive application of chemical fertilizer.Therefore,studying the effects of organic fertilizer substitution and planting density on rice is of great significance to ensure the transformation of rice production to high yield,high quality,green and safe.In this study,Zhongzao 25 and Zhuliangyou 819 were used as experimental materials to carry out two-factor split plot test.The main area was fertilizer treatment（using the principle of organic fertilizer and other nitrogen substitution）.The fertilizer treatments were set as follows:no nitrogen fertilizer（CK）,conventional nitrogen fertilizer（M₀）,25%commercial organic fertilizer replacement(M₂₅),50%commercial organic fertilizer replacement(M₅₀),75%commercial organic fertilizer replacement(M₇₅)and 100%commercial organic fertilizer replacement(M₁₀₀).Planting density was 10cm×25cm（HD）,18cm×25cm（LD）.The response of rice yield,growth,nitrogen use efficiency and rice quality to different organic fertilizer substitution ratios and density combinations was studied to determine the optimal organic fertilizer substitution ratio and optimal density.The main research results are as follows:（1）From the growth and development point of view,under 10cm×25cm（HD）,compared with CK（no nitrogen fertilizer）,Zhongzao 25 and Zhuliangyou 819 under each fertilizer treatment,leaf area index,photosynthetic potential,dry matter mass at maturity and dry matter accumulation at full heading-maturity stage were increased.Among them,the photosynthetic potential,dry matter mass at maturity stage and dry matter accumulation at full heading-maturity stage of Zhongzao 25 with 50%commercial organic fertilizer(M₅₀)were the highest,which were 103.77%,50.99%and 100.61%higher than those of CK（no nitrogen fertilizer）,respectively.Conventional nitrogen fertilizer（M₀）increased the most in Zhuliangyou 819,which was 104.24%,61.02%and 97.7%higher than CK（no nitrogen fertilizer）,respectively.（2）Compared with CK（no nitrogen fertilizer）,the application of nitrogen fertilizer increased the yield of rice.Under the treatment of 10cm×25cm（HD）,the yield of conventional nitrogen fertilizer（M₀）was the highest.Compared with conventional nitrogen fertilizer（M₀）,the yield and grain number per spike of 25%and 50%organic fertilizer were not significantly different,while the effective panicles of Zhongzao 25 and Zhuliangyou 819were significantly increased under 50%commercial organic fertilizer(M₅₀).Under18cm×25cm（LD）treatment,the yield of Zhongzao 25 and Zhuliangyou 819 under conventional nitrogen fertilizer（M₀）treatment was significantly higher than other treatments.Therefore,under the treatment of 10cm×25cm（HD）,50%commercial organic fertilizer replacement(M₅₀)treatment could stabilize the yield of rice by increasing the effective panicle number of rice.（3）The application of nitrogen fertilizer increased the nitrogen accumulation of Zhongzao 25 and Zhuliangyou 819.Compared with conventional nitrogen fertilizer（M₀）,the nitrogen accumulation of Zhongzao 25 with only 50%commercial organic fertilizer replacement(M₅₀)at jointing stage increased by 11.94%compared with conventional nitrogen fertilizer（M₀）,and its treatment decreased.The organic fertilizer replacement treatment of Zhuliangyou 819 decreased at all stages.The total nitrogen accumulation was10cm×25cm（HD）>18cm×25cm（LD）.Compared with CK（no nitrogen fertilizer）,the N dry matter production efficiency and N rice production efficiency of the two varieties were the lowest under conventional N fertilizer（M₀）treatment.Among them,Zhongzao 25 and Zhuliangyou 819 decreased by 21.07%,30.40%and 30.39%,26.4%respectively compared with CK（no nitrogen fertilizer）.Nitrogen partial productivity and nitrogen agronomic efficiency decreased with the increase of organic fertilizer replacement ratio.（4）Compared with CK（no nitrogen fertilizer）,the head rice rate and length-width ratio of Zhongzao 25 under each fertilizer treatment increased,and the conventional nitrogen fertilizer（M₀）and 50%commercial organic fertilizer(M₅₀)increased most,and the head rice rate increased by 19.36%and 23.18%respectively compared with CK（no nitrogen fertilizer）.But chalky grain rate and chalkiness increased.Except for the decrease of M₀ and M₁₀₀,amylose content increased and protein content increased.The milled rice rate and chalkiness of Zhuliangyou 819 decreased under each treatment.The milled rice rate decreased the most with M₀,which was 3.86%lower than that of CK（no nitrogen fertilizer）.The chalkiness was the lowest with M₅₀,which was 20.39%lower than that of CK（no nitrogen fertilizer）.The protein content increased by 12.28%～22.83%.（5）With the extension of storage period,the brown rice rate,chalky grain rate and chalkiness of Zhongzao 25 and Zhuliangyou 819 decreased gradually,the milled rice rate and amylose content of Zhongzao 25 decreased first and then increased,the milled rice rate and amylose content of Zhuliangyou 819 decreased gradually,the whole milled rice rate of Zhongzao 25 increased with the extension of storage period,and there was no significant change in the whole milled rice rate of Zhuliangyou 819 and the length-width ratio of the two varieties.The comprehensive evaluation results of membership function showed that the quality of rice was the best when the storage period was 150 days after harvest.（6）The membership function was used to comprehensively evaluate the growth,yield,nitrogen utilization and rice quality of Zhongzao 25 and Zhuliangyou 819,respectively.The results showed that the yield,growth and nitrogen utilization of Zhongzao 25 and Zhuliangyou 819 under conventional nitrogen fertilizer（M₀）+10cm×25cm（HD）were the best,followed by conventional nitrogen fertilizer（M₀）+18cm×25cm（LD）and 50%commercial organic fertilizer replacement(M₅₀)+10cm×25cm（HD）;the comprehensive evaluation of rice quality was the best under the treatment of 100%commercial organic fertilizer substitution(M₁₀₀)+10cm×25cm（HD）,followed by 75%commercial organic fertilizer substitution(M₇₅)+18cm×25cm（LD）and 50%commercial organic fertilizer substitution(M₅₀)+10cm×25cm（HD）.In summary,the application of 50%commercial organic fertilizer instead of(M₅₀)+10cm×25cm（HD）cultivation mode in special rice can make rice maintain stable yield and better coordinate the processing,appearance and cooking quality of rice,so as to achieve green and efficient production of early season indica rice.