Effects Of Controlled Release Fertilizer And Urea Combined Application On Yield,Quality Of Rice In Abandoned Yellow River Course Of Northern Jiangsu Province

The experiment was conducted in Likou Town,Siyang County,Jiangsu Province,an out-of-school base of Yangzhou University from 2018 to 2019.The soil was sandy soil,and the previous crop was wheat.The medium-maturity medium-japonica rice nanjing 505 and suxiu 867 were used in the study.The field experiment was conducted using the split-plot design with two factors.The main plot was two fertilizer application methods:mixed application of controlled-release urea and conventional urea as basal fertilizer(BC),and mixed application of controlled-release urea and conventional urea as basal fertilizer and top dressing at panicle initiation(BC+PU),and the subplot was three types of resin coated urea with controlled-release days of 80,100 and 120 days,respectively,and conventional urea application was designed as the control(CK).There were 7 treatments.With the N rate of 270 kg/hm2 for all treatments,the controlled-release fertilizer treatments were as follows:80 days resin coated urea with BC method(80BC),100 days resin coated urea with BC method(100BC),120 days resin coated urea with BC method(120BC),80 days resin coated urea with BC+PU method(80BC+PU),100 days resin coated urea with BC+PU method(100BC+PU),120 days resin coated urea with BC+PU method(120BC+PU)and CK.The aim was to study the effect of controlled-release fertilizers with different release days and fertilizer application methods on the yield,nutrient uptake and utilization,leaf photosynthetic characteristics and quality formation of rice,and to provide scientific basis for fertilizer management of high-quality rice production in the old course belt area of the Yellow River in northern Jiangsu.The main results were as follows:1.Under the same fertilizer application method,the yield of 80 days resin coated urea treatment>100 days resin coated urea treatment>120 days resin coated urea treatment.Under the same release days of controlled-release urea treatment,the yield of BC+PU treatment was higher than that of BC treatment.The results showed that 80 days resin coated urea with BC+PU method was the best for increasing yield and was significantly higher than CK,which attributed to the increase of total number of spikelets and 1000-grain weight on the basis of stabilizing panicle number.The leaf area index,photosynthetic potential and dry matter accumulation of rice were higher than the other treatments in the middle and late growth stage.The dry matter accumulation and transportation could be well coordinated,the dry matter accumulation after heading increased,and could achieve high yield.In 120BC and 120BC+PU treatments,the number of tillers,leaf area and dry matter accumulation at each stage of were significantly lower than CK,the number of panicles and the total number of spikelets were significantly lower than CK,and the yield decreased significantly.In 100BC and 100BC+PU treatment,The number of tillers of with was less than CK,and the number of panicles,spikelets per panicle,and total spikelet number were comparable to CK.Although higher seed setting rate and 1000-grain weight could be maintained in the late stage,the yield could not be improved due to the low total spikelet number in the population.2.The results showed that the chlorophyll content,Pn,Tr,Gs,Fv/Fm and Y(Ⅱ)of controlled-release fertilizer treatments were higher than those of CK after heading stage of rice.The chlorophyll contents after heading in all the controlled release fertilizers except 80BC treatment were significantly higher than CK.The Pn of 80BC+PU and 100BC+PU were significantly higher than CK at 21 d after heading,and the Y(Ⅱ)values of 120BC,120BC+PU,80BC+PU and 100BC+PU treatments were significantly higher than CK from 28 d to 35 d after heading.At the same time,the application of BC+PU enhanced the photosynthetic characteristics of rice than BC.The SPAD value of 80BC+PU treatment was significantly higher than that of 80BC treatment by 2.16%-9.06%.The results showed that the application of fertilizer types with longer controlled release period,such as 120 days resin coated urea and the application of 80 days resin coated urea and 100 days resin coated urea with shorter controlled release period combined with BC+PU method,were conducive to improve the chlorophyll content,Pn and Y(Ⅱ)in leaves at the middle and late growth stage of rice,and delay the senescence of rice plants.3.This study showed that the total nitrogen accumulation at heading and maturity stage of the treatment with 80BC+PU combined with top dressing at panicle initiation was significantly higher than CK,and the accumulation at jointing to heading stage and heading to maturity stage were 5.62%-8.3%and 7.15%-18.53%higher than CK,respectively.NRE(nitrogen recovery use efficiency),AE(agronomic nitrogen use efficiency),PE(physiological nitrogen use efficiency)and PFP(partial factor productivity of applied nitrogen)decreased with the increase of controlled release days of controlled release fertilizers.The application effect of 80 days resin coated urea was better than that of 100 days resin coated urea and 120 days resin coated urea.For the two fertilizer application methods,the 80 days resin coated urea and the 100 days resin coated urea with BC+PU application method can slightly improve the NRE,AE,PE and PFP compared with the corresponding BC treatment,among them,the NRE,AE,PFP under the treatment of 80BC+PU were significantly increased as compared with those under CK by 9.19%-12.90%,12.96%-14.46%and 5.36%-6.21%,respectively.4.In terms of processing quality,there was no significant difference among all treatments.There was no significant difference in appearance quality,nutrition quality,cooking taste quality and RVA profile characteristics of rice between 80 days resin coated urea and conventional urea application.The 80 days resin coated urea with BC method treatment increased the amylose content,gel consistency and taste value,and increased peak viscosity,trough viscosity,final viscosity and breakdown value,reduced the consistence value,and improved the cooking taste quality.The 100 days resin coated urea and 120 days resin coated urea treatments increased the protein content,reduced chalkiness percentage and chalkiness degree,and decreased the amylose content and taste value of cooking quality,which also brought about a steady decline in peak viscosity,trough viscosity,breakdown,final viscosity,and finally obtained a poor cooking quality.Compared with BC treatment,BC+PU treatment improved appearance quality and nutrition quality,and reduced the rice cooking quality,the main reason was that the BC+PU treatment kept leaves from premature aging,promoted nitrogen transport,improved grain filling quality and grain protein content on account of the backward shift in nitrogen efficiency.