控释尿素配比对华南双季稻产量、氮素吸收累积及氮肥利用率的影响

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

【目的】探讨2种不同释放期控释尿素不同配施模式对水稻产量、氮素吸收累积及氮肥利用率的影响,以期为我国华南双季稻区优化施氮提供科学依据。【方法】采用田间试验,设6个处理:T1,不施氮处理;T2,速效氮肥单施处理;T3,60 d控释尿素单施处理;T4,90 d控释尿素单施处理;T5,60 d控释尿素配施处理(30%60 d控释尿素+70%速效氮肥);T6,90 d控释尿素配施处理(30%90 d控释尿素+70%速效氮肥)。动态分析不同处理的水稻叶片SPAD值,灌浆后地上部、剑叶、穗部氮含量及干物重;收获期测定水稻产量及产量构成因素;计算不同施肥处理的氮肥利用效率。【结果】由早、晚稻年平均产量可知,施用控释尿素的T3~T6处理较速效氮肥单施的T2处理产量显著增加(P<0.05,下同),增幅为4.7%~8.5%。其中,T5处理产量(5.8 t/ha)最高,显著高于T3和T4处理,但与T6处理差异不显著(P>0.05)。与T1处理相比,施用氮肥提高了早稻剑叶SPAD值,T6处理的剑叶SPAD值一直处于较高水平,且始终高于T5处理,T3处理的剑叶SPAD值总体高于T4处理。T5处理产量较高归因于其有效穗数和穗粒数同时保持较高水平。随着时间的推移,水稻植株地上部氮含量逐渐下降,而干物重逐渐增加,且各处理不同部位干物重存在明显差异,至收获期,T5和T6处理穗干物重均显著高于T2处理,但T5处理地上部氮素累积量相对低于其他施氮处理。各控释尿素处理的氮素表观回收率和氮肥农学效率均显著高于T2处理,其中氮素表观回收率以T3处理最高(35.7%),氮肥农学利用率以T5处理最高(7.3%)。【结论】等氮肥用量下,30%60 d控释尿素配施70%速效氮肥处理在提高籽粒产量和养分利用效率方面具有优势,可作为华南双季稻区的推荐施肥模式。

【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 fertilization 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 measurements 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 harvest 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 application 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 treatment 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 number and grain number per panicle.Over time,the aboveground N content in rice gradually decreased,while dry matter accumulation 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%).【Conclusion】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.