Experimental Study On Growth Characteristics And Nitrogen Utilization Of Rice With Alternate Wetting-drying Slow Release Fertilizer

Water and fertilizer regulation is an important reason for high yield of rice.In order to reveal the effect of slow-release fertilizer on rice growth characteristics and nitrogen utilization under alternate wetting and drying,Zhanghe Irrigation District in Hubei Province was selected as the research area.The rice variety Zuanliangyouchaozhan was used as the experimental material.Two experiments were designed under the condition of nitrogen application level of 180 kg/hm².（1）From May to September 2020,two irrigation modes of continuous flooding irrigation W1 and alternate wetting and drying W2 were carried out,and the rice planting plot experiment under the mutual coupling condition of traditional fertilizer N1 and slow-release fertilizer N2（with no fertilizer N0 as the CK）was carried out.The rice growth characteristics and nitrogen utilization under different water and fertilizer conditions were studied to determine the suitability of alternate wetting and drying slow-release fertilizer.（2）In May–September 2019 and 2020,two irrigation modes of continuous flooding irrigation W1 and alternate wetting and drying W2 were carried out with five different fertilization levels of traditional fertilizer N1 and slow-release fertilizer N2（F（0.5）,F（0.75）,F（1.0）,F（1.25）,F（1.5）in 2019,and F（0.8）,F（0.9）,F（1.0）,F（1.1）,F（1.2）in 2020）.The optimal fertilization level of slow-release fertilizer was studied through yield.The results showed that:（1）The plant height,tiller number,chlorophyll SPAD value and leaf area index of slow-release fertilizer under different irrigation modes were 10.8%,12.5%,17.5%and 41.9%higher than those of traditional fertilizer,respectively,indicating that the promoting effect of slow-release fertilizer on plant height,tiller number,chlorophyll SPAD value and leaf area index of rice was better than that of traditional fertilizer.Slow-release fertilizer had a better promoting effect on rice tiller number under alternate wetting and drying mode,and more ineffective tillers were produced under continuous flooding irrigation mode.However,slow-release fertilizer has a better promoting effect on plant height and leaf area index under continuous flooding irrigation mode,and the difference in chlorophyll SPAD value of rice under different irrigation modes was not obvious.（2）Slow-release fertilizer had a better promoting effect on the total dry matter content and dry matter accumulation in various organs of rice compared with traditional fertilizer.The simulation accuracy of total dry matter by Logistic model was good,and the R²of all treatments was between 0.961 and 0.991.Compared with traditional fertilizer,slow-release fertilizer had better promotion effect on the duration of rapid growth period T,the maximum growth rate₈)and the average growth rate.The promoting effect of alternate wetting and drying on dry matter of rice was not as good as that of traditional flooding irrigation,but alternate wetting and drying had a higher promoting effect on stem and leaf transformation.The combination of slow-release fertilizer and alternate wetting and drying has a better promoting effect on stem and leaf transformation.（3）Compared with traditional fertilizer,slow-release fertilizer increased nitrogen content by 11.8%～15.5%and nitrogen accumulation by 43.1%～43.3%.At the same time,the nitrogen transport amount and apparent transport contribution rate of stem and leaf under slow-release fertilizer treatment were higher than those of traditional fertilizer treatment,indicating that slow-release fertilizer had better promotion effect on the transformation of nitrogen from stem and leaf to panicle than traditional fertilizer.Compared with traditional fertilizer,slow-release fertilizer significantly increased nitrogen partial productivity,nitrogen agronomic efficiency and nitrogen use efficiency.Alternate wetting and drying had better promoting effect on nitrogen grain production efficiency and nitrogen agronomy efficiency of rice,and the combination of alternate wetting and drying and slow-release fertilizer could improve nitrogen agronomy efficiency.（4）There was a significant positive correlation between the total dry matter,nitrogen accumulation and nitrogen partial productivity,the number of panicles per unit area,the number of grains per panicle and yield in each growth period.Compared with the traditional fertilizer treatment,slow-release fertilizer increased the total dry matter,nitrogen accumulation,the number of panicles per unit area and the number of grains per panicle,so as to improve the yield.Under different irrigation modes,the average yield of slow-release fertilizer treatment was 13.8%higher than that of traditional fertilizer treatment,but the yield of slow-release fertilizer combined with flooding irrigation was 2.9%higher than that of alternate wetting and drying.Each fertilization level of slow-release fertilizer was only 0.9times the amount of fertilizer in two irrigation modes were higher than the standard fertilizer,indicating that 0.9 times the mass standard fertilizer was the best fertilization level for yield.Considering that slow-release fertilizer had a better promoting effect on stem and leaf transformation under alternate wetting and drying and improved nitrogen agronomic efficiency,the irrigation water productivity of W2 treatment was 28.7%higher than that of W1 treatment on average,and the yield was only slightly lower by 2.9%,indicating that the combination of alternate wetting and drying and slow-release fertilizer still had certain suitability.