Effects of different ratios of controlled release urea on grain yield,nitrogen uptake and accumulation,and nitrogen fertilizer use efficiency of double cropping rice in southern China
[Objective]This study investigated the effects of different application modes of two controlled release urea(CRU)with different release periods on grain yield,nitrogen(N)uptake and accumulation,and N use efficiency(NUE),providing scientific guidance for optimizing N fertilization in double cropping rice region in southern China.[Method]A field experiment was conducted,six treatments were established:T1,no N application;T2,single basal fer-tilization with normal urea only;T3,single basal fertilization application of 60 d CRU only;T4,single basal fertilization application of 90 d CRU only;T5,60 d CRU treatment(single basal fertilization application of 30%60 d CRU and 70%normal urea);T6,90 d CRU treatment(single basal application of 30%90 d CRU and 70%normal urea).Dynamic mea-surements were taken for the SPAD value of flag leaf,N content and dry matter accumulation in shoot,flag leaf,leaf and panicle after grain filling in early rice.The grain yield and yield components of double cropping rice were detected at har-vest and the NUE were calculated for each treatment.[Result]Annual average yield data of early and late rice showed that CRU application treatments(T3-T6)significantly increased grain yield by 4.7%-8.5%compared with the single applica-tion of urea(T2)(P<0.05,the same below).Among these treatments,T5 achieved the highest grain yield(5.8 t/ha),which was significantly higher than that of T3 and T4,but not significantly different from T6(P>0.05).Compared with T1 treatment,the application of nitrogen fertilizer improved the SPAD value of early rice,the SPAD value of T6 treat-ment was always at a high level and always higher than T5 treatment,and the SPAD value in flag leaf of T3 treatment was generally higher than that of T4 treatment.The higher yield of T5 was mainly attributed to its higher effective panicle num-ber and grain number per panicle.Over time,the aboveground N content in rice gradually decreased,while dry matter ac-cumulation gradually increased.Obvious differences in dry matter accumulation were observed among treatments and plant parts.At harvest,T5 and T6 showed significantly higher panicle dry weight than T2.However,the aboveground N accumulation of T5 was relatively lower than that of other fertilization treatments.Meanwhile,the recovery efficiency of N fertilizer(REN)and agronomic efficiency of N fertilizer(AEN)of CRU treatments were significantly higher than those of T2 treatment,among which the highest REN was observed in T3(35.7%)and the highest AEN in T5(7.3%).[Conclu-sion]Under the same N application rate,combining 30%60 d CRU with 70%normal urea offers advantages in improving grain yield and nutrient use efficiency.This fertilization mode is recommended for double-cropping rice region in southern China.
controlled release ureanutrient allocation and fertilizationnitrogen uptake and accumulationnitrogen use efficiencyyield
万方数据
维普
