[Objective] The effects of reducing nitrogen and phosphorus application on rice growth,grain yield,and nitrogen use efficiency were investigated for providing scientific basis to reduce fertilizer application reasonably in Taihu lake basin,China.[Method] A field plot experiment was performed to study the effects of reducing nitrogen and phosphorus application on photosynthetic characteristics of the flag leaves,grain yield,and nitrogen use efficiency of the late-maturing mid-season rice (Oryza sativa L.) cultivar Nanjing 9108,which was widely grown for food production in Taihu lake basin,China.[Result] Reducing nitrogen application had significant effects on the leaf pigment content and net photosynthesis rate (Pn) of the Flag Leaves.Compared with conventional fertilization conditions (T1,the plots applied with chemical fertilizer as in conventional practice),chlorophyl a (Chl a) content,total content of chlorophyll a and chlorophyll b (Chla + b),and net photosynthesis rate (Pn) of flag leaves.Under T2 treatment (reducing application 15 ％ of nitrogen fertilizer compared with T1,and phosphorus fertilizer was same with T1),the content of Chl a and Chla + b,and Pn decreased slightly,but no significant difference was found between these treatments during the early filling stage (15 days after heading).With the increase of reducing nitrogen fertilizer application and the extension of treatment time,pigments content and Pn of flag leaves decreased significantly.And,during the late filling stage (35 days after heading),the Chla,Chlb,and Chla + b content,and Pn of flag leaves decreased significantly by 15.61％,22.28 ％,16.97 ％,and 18.47 ％ under T3 treatment (reducing application 30 ％ of nitrogen fertilizer compared with T1,and phosphorus fertilizer was same with T1),respectively.However,T4 (reducing application 15 ％ of phosphorus fertilizer compared with T1,and nitrogen fertilizer was the same with T1) and T5 (reducing application 30 ％ of phosphorus fertilizer compared with T1,and nitrogen fertilizer was same with T1)treatments had no significant effects on the pigments content of flag leaves,but Pn decreased significantly by 14.15 ％ under T5 treatment,during the late filling stage.Compared with T1 treatment,T2,T3 decreased significantly rice grain yield by 6.27 ％-12.91％,which might be resulted from the significant decrease of total spike number.And,reducing phosphorus application (T4-T5) had no significant effects on the rice grain yield.However,T2,T3 significantly increased the nitrogen partial factor productivity,nitrogen agronomic efficiency,and nitrogen physiological efficiency by 15.04 ％-31.88 ％,10.74 ％-13.84 ％,and 8.16 ％-9.57 ％,respectively.Furthermore,reducing nitrogen and phosphorus application (T2-T5) treatments had no significant effects on the apparent nitrogen utilization efficiency of Rice (Oryza sativa L.) Cultivar Nanjing 9108.[Conclusion] From the view of photosynthetic characteristics of the flag leaves,grain yield,and nitrogen use efficiency,moderate reduction of nitrogen (15 ％) and phosphorus (15 ％) application was feasible in the rice production in Taihu lake basin,China.%[目的]研究氮磷减施对水稻生长、产量及氮素利用的影响,为江苏太湖地区水稻生产合理减肥提供一定的理论依据.[方法]以江苏省大面积生产应用的迟熟中粳水稻品种南粳9108为试材,采用野外田间小区试验的方法,研究了氮磷减施对水稻剑叶色素含量、光合作用主要参数、稻谷产量及氮素利用率的影响.[结果]氮肥减施对水稻叶片色素含量及净光合速率(Pn)影响较大.较常规施肥处理(T1)而言,减施15％氮肥处理(T2)条件下,灌浆前期水稻叶片Chla、Chla+b含量及叶片净光合速率均未显著降低.随氮肥减施幅度的增大和处理时间的延长,叶片色素含量及Pn显著下降.减施30％氮肥处理(T3)条件下,灌浆后期Chla、Chlb、Chla+b含量及Pn显著下降15.61％、22.28％、16.97％和18.47 ％(P＜ 0.05).然而,减磷处理(T4～T5)对水稻叶片色素含量未有显著影响,且Pn仅在减施30％磷肥处理(T5)条件下于灌浆后期呈现显著下降趋势,下降幅度达14.15 ％(P＜0.05).氮肥减施(T2～T3)降低水稻产量达6.27％～12.91％,总穗数的显著降低是减产的主要原因,磷肥减施(T4～T5)对水稻产量无显著影响.然而,氮肥减施处理(T2～T3)可显著提高水稻氮肥偏生产力、氮素农学利用率及氮肥生理利用率分别达15.04％～31.88％、10.74％～13.84％和8.16％～9.57％.同时,氮磷减施(T2～T5)各处理对水稻氮素表观利用率的影响也未达显著水平.[结论]从水稻叶片光合特性、稻谷产量及氮素利用率等综合考虑,氮磷适度减施在江苏太湖地区水稻生产上是可行的.
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