Effects Of Different Irrigation Methods And Nitrogen Application Rate On Nitrogen Absorption And Utilization Of Double-season Super Rice

In order to understand the effects of water and nitrogen on the yield of double-season super rice and nitrogen absorption and utilization,and promote the high-yield and stable yield of double-season super rice,Zhongjiazao 17 and Hyou 518 were used as materials in early and late 2018 Set two irrigation methods(regular irrigation G1,wet irrigation G2),4levels of nitrogen application[no nitrogen application N0(0kg/hm~2),low nitrogen N1(160kg/hm2),medium nitrogen N2(200kg/hm~2),high Nitrogen N3(240kg/hm~2)]was tested in a greenhouse and sheltered from the rain.The main results are as follows:(1)Irrigation methods and nitrogen application have a certain influence on the growth and development of super rice,among which the nitrogen application has a greater influence.Compared with humid irrigation,the leaf area index of conventional irrigation was 4.59%,6.95%,13.98%,7.51%higher in early rice at tillering stage,booting stage,full heading stage,and milk ripening stage;late rice was 15.07%,16.37%higher,15.66%,20.15%.From different nitrogen application levels,the leaf area index obviously increased with the increase of nitrogen application level.(2)The relative chlorophyll content(SPAD value)is little affected by the irrigation method,but the effect of nitrogen application is obvious.In each period,the SPAD value of the leaves without nitrogen treatment was much lower than that of nitrogen treatment,and the difference reached a very significant level.At the same time,with the increase of nitrogen application,the SPAD value of leaves increased.In the early rice variety Zhongjiazao 17 in the tillering stage,booting stage,full ear stage and milk maturity stage,the high nitrogen level N3 increased by 8.91%,9.24%,12.06%,and 10.96%,respectively,compared to N1.The SPAD value of early rice is slightly higher than that of late rice,which may be caused by the variety.(3)Irrigation methods have a certain effect on dry matter accumulation,but the effect of nitrogen application is greater.The dry matter accumulation of early rice Zhongjiazao 17was between G2 and T1 during the tillering stage,booting stage and full heading stage,the difference was not significant,but the milk maturity stage in turn G2 was greater than G1,which was 17.16%higher,The difference reached a significant level.Between different amounts of nitrogen application,the general trend is N3>N2>N1>N0,that is,the greater the amount of nitrogen application,the more dry matter accumulation,the difference between the different treatments is significant.(4)Irrigation method has no obvious effect on photosynthetic rate,and nitrogen application level has a greater impact on photosynthetic rate.The leaf photosynthetic rate was the highest at the middle nitrogen level N2.The early rice Zhongjiazao 17 reached 23.43,25.26 and 19.21μmol/m~2·s at the booting stage,full heading stage and milk ripening stage,respectively.The highest photosynthetic rate of early rice and late rice was G2N2 during the milk ripening period,and it was significantly or significantly different from other treatments.(5)Irrigation methods and the amount of nitrogen application both affect the yield of super rice.The performance is that humid irrigation is higher than conventional irrigation.The application of nitrogen fertilizer can significantly increase the yield of rice,and the increase in yield of medium and high nitrogen levels is more obvious.The yield of G2N3was the highest in the early and late rice,which were 8617.6kg/hm~2 and 10738.4kg/hm~2,respectively.Under conventional irrigation conditions,the highest yield appeared at medium nitrogen level N2,and under humid irrigation conditions,the highest yield appeared at high nitrogen level N3,indicating that under humid irrigation conditions,rice is more resistant to fertilizers and yields.(6)Irrigation methods and the amount of nitrogen application both affect the utilization rate of nitrogen fertilizer,and humid irrigation is more conducive to the improvement of the utilization rate of nitrogen fertilizer.From the perspective of nitrogen application level,the agronomic utilization rate and absorption utilization rate of nitrogen fertilizer are the highest with low nitrogen N1 or medium nitrogen N2.Considering the comprehensive yield and utilization rate of nitrogen fertilizer,the best water and nitrogen combination in this study is G2N2 treatment,that is,humid irrigation,and the nitrogen application rate is 200kg/hm~2.