| The experiment was conducted in Diaoyu Town,xinghua city,Jiangsu Province from 2018 to 2019.Rice cultivars of Nanjing 9108 was adopted as material under the pure nitrogen condition of 270 kg hm-2 in this study.Rice was cultivated with two methods including mechanical transplanting with pothole seedlings(MP)and mechanical transplanting with carpet seedlings(MC).Controlled-release fertilizer and quick-acting nitrogen fertilizer were mixed at a ratio of 5:5.Controlled-release fertilizer was mixed from four different release periods(40,80,100,and 120 days)at a ratio of 1:4 to form three mixing modes(40+80,40+100,and 40+120).Conventional urea split fertilization(CK)was used as a control,and the effects of different controlled-release fertilizer ratios on yield formation,nitrogen absorption and utilization and rice quality of late-maturing medium japonica rice were studied.The main research results are as follows:1.Under the same fertilizer treatment,compared with mechanical transplanting with carpet seedlings(MC),the rice yield of mechanical transplanting with pothole seedlings(MP)was significantly increased by 3.9%～4.9%.The reason was that the MP could improve the accumulation of photosynthetic substances in the middle and late stages and obtain larger panicle type with higher grain number per panicle,seed setting rate,and 1000-grain weight.Under the cultivation mode of MP and MC,compared with CK,the yield of 40+80 and 40+100 controlled-release fertilizer treatments were higher than CK,and the yield of 40+100 controlled-release fertilizer treatments was the highest,which was significantly increased by 7.3%～9.2%.The reason was that 40+100 controlled-release fertilizer treatment had higher effective panicle number and population glume amount.Compared with 40+80 and 40+120 controlled-release fertilizer treatments,the nutrient absorption law of 40+100 controlled-release fertilizer treatment was more consistent with Nanjing 9108,which not only ensured the occurrence of early tillering,but also ensured the stable production of photosynthetic substances at later stage,thus obtaining stable panicle number,grains per panicle,and 1000-grain weight.2.Under the same fertilizer treatment,mechanical transplanting with carpet seedlings(MC),the nitrogen absorption rate of mechanical transplanting with pothole seedlings(MP)was lower from transplanting to jointing stage,and the nitrogen accumulation of rice was relatively lower at this stage.At jointing stage to heading stage and heading stage to maturity stage,the nitrogen absorption rate of MP is higher than that of MC.so the nitrogen accumulation of MP in this stage is higher.Compared with MP.rice with MC has higher nitrogen utilization efficiency.Compared with CK,the rice treated with controlled-release fertilizer had higher nitrogen absorption rate and nitrogen accumulation from transplanting to jointing stage under the mode of pot seedlings and blanket seedlings by machine.From the jointing stage to the heading stage,only the 40+100 controlled-release fertilizer treatment rice had a higher nitrogen absorption rate than CK,while the 40+80 and 40+120 controlled-release fertilizer treatments had a lower nitrogen absorption rate than CK.From heading to maturity,the nitrogen absorption rate and nitrogen accumulation of rice treated with 40+80 and 40+100 controlled-release fertilizers were lower than those of CK.while those treated with 40+120 controlled-release fertilizers were higher than those of CK.The nitrogen recovery rate of rice under controlled release fertilizer treatment was higher than CK.The agronomic nitrogen use efficiency,physiological nitrogen use efficiency and partial nitrogen productivity of rice under 40+80 and 40+100 controlled-release fertilizer treatments were higher than those of CK,with 40+100 controlled-release fertilizer treatment being the highest and 40+120 controlled-release fertilizer treatment being lower than CK.In terms of nitrogen grain production efficiency,only 40+100 controlled release fertilizer treatments were higher than CK,while 40+80 and 40+120 controlled release fertilizer treatments were lower than CK.3.Under the same fertilizer treatment,the mechanical transplanting with pothole seedlings(MP)increased the brown rice rate,milled rice rate and head rice rate,and improved the processing quality of rice.Compared with mechanical transplanting with carpet seedlings(MC),the MP increased the chalky grain rate and chalkiness degree of rice,and decreased the appearance quality of rice.However,the protein content of rice in MP was higher than that in MC,which was beneficial to improve the nutritional quality of rice.The amylose content and reduction value of rice with MP were lower than those with MC,while the peak viscosity,hot pulp viscosity,disintegration value and final viscosity were higher than those with MC Therefore,the taste value of rice with MP is lower than that with MC.Compared with CK,rice with controlled-release fertilizer has higher brown rice rate,milled rice rate and head rice rate under the planting mode of MP and MC.Controlled release fertilizer not only improves the processing quality of rice,but also reduces the chalky grain rate and chalkiness degree of rice and improves its appearance quality.Compared with CK,the treatment of controlled release fertilizer effectively increased the peak viscosity,final viscosity,disintegration value and hot paste viscosity of rice,and reduced the reduction value of rice,which was beneficial to improve the eating quality of rice.Compared with CK,rice with 40+80 and 40+100 controlled-release fertilizers had lower protein content,higher amylose content and higher gel consistency,so the taste value of rice with 40+80 and 40+100 controlled-release fertilizers was higher than CK.The protein content of rice treated with 40+120 controlled release fertilizer was higher than CK,while the amylose content and gel consistency were lower than CK,so the taste value was lower than CK.In summary,under the same fertilizer treatment,the late-maturing medium japonica rice Nanjing 9108,mechanical transplanting with pothole seedlings(MP)has a better yield increase.and at the same time it also improves the nitrogen utilization efficiency of the rice and improves the quality of the rice.Among the three types of controlled-release fertilizer treatments,the 40+100 controlled-release fertilizer ratio can better meet the nutrient requirements of late-maturing medium japonica rice at various stages of growth and development,and can build a high-yield population,ensure the accumulation of photosynthetic products in the later stage,and obtain high yields.And improve rice nitrogen use efficiency,optimize rice quality.This indicated that compared with mechanical transplanting with carpet seedlings(MC),mechanical transplanting with pothole seedlings(MP)is more conducive to the high yield of late-maturing mid-japonica rice.At the same time,under the condition of mechanical transplanting with pothole seedlings(MP),the ratio of controlled release fertilizer of 40+100 days can be used as the best scheme for simplified fertilization of late-maturing mid-japonica rice. |
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