不同施氮量对花后高温春小麦叶绿素含量及荧光特性的影响

Effects of different nitrogen application rates on chlorophyll content and fluorescence characteristics of spring wheat under high temperature after anthesis

【目的】研究不同施氮量对花后高温下春小麦叶绿素荧光特性的影响,为分析氮素营养调控春小麦高温危害的内在机理提供理论依据。【方法】以宁春4号和宁春47号为材料,设施纯氮120 kg/ha(N1)、240 kg/ha(N2)和300kg/ha(N3)3个施氮量处理,以不施氮为对照(CK),于花后18~22 d进行(35±2)℃高温处理,测定花后7、14、23、28和33 d不同处理的叶绿素含量及荧光参数。【结果】高温胁迫后(花后23~33 d),与CK相比,3个氮肥处理整体上可增加宁春4号和宁春47号的叶片SPAD值、最大荧光(F_m)和可变荧光(F_v),降低初始荧光(F_o),使F_v/F_o、F_v/F_m上升、F_o/F_m下降,其中N1和N2处理较CK增加或降低的幅度较明显。同时,花后23~28 d,N1和N2处理的单位反应中心吸收的光能(ABS/RC)、单位反应中心捕获的用于还原QA的能量(TR_0/RC)和单位反应中心耗散的能量(DI_0/RC)显著高于CK(P<0.05,下同),花后33 d时显著低于CK;单位反应中心捕获的用于电子传递的能量(ET_0/RC)在花后23~33 d均表现为N2>N1>N3>CK。【结论】适量施用氮肥可缓解高温对春小麦光合器官结构和功能的伤害,有助于提高其光合性能。

[Objective]In the present study, effects of different nitrogen application rates on chlorophyll fluorescence characteristics of spring wheat under high temperature after anthesis were investigated, in order to provide guidance for analysis for inner mechanism of nitrogen nutrition regulation of high temperature harm to spring wheat. [Method] Ningchun 4 and Ningchun 47 were used as plant materials. Three nitrogen application rates, 120 kg/ha（N1 ）, 240 kg/ha （N2） and 300 kg/ha （N3）, were set and no nitrogen application was treated as control （CK）. High temperature treatment during 18-22 d after anthesis on wheat was conducted. Chlorophyll content and fluorescence parameters were measured 7, 14, 23, 28 and 33 d after anthesis. [Result]Under high temperature stress（23-33 d after anthesis）, SPAD values, maxi- mum fluorescence（Fro） and variable fluorescence（Fv） in leaves of Ningchun 4 and Ningchun 47 under three nitrogen application rates increased, but original fluorescence（F o） declined, which rose Fv/Fo and Fv/Fm and decreased Fo/Fm. The variation ranges of wheats in N1 and N2 treatment were larger than the one in N3 treatment compared with CK. Absorption flux per RC （ABS/RC）, trapped energy flux per RC （TRo/RC） and dissipated energy flux per RC （DIo/RC） in N1 and N2 treatments were significantly higher than those of CK during 23-28 d after anthesis（P〈0.05 ,the same below）, and significantly lower than those of CK on day 33 after anthesis. Electron transport flux per RC（ET0/RC） was expressed as N2〉N1〉N3〉CK during 23-33 d after anthesis. [Conclusion]Appropriate application of nitrogen fertilizer can alleviate the damages to structure and function of spring wheat photosynthetic organ caused by high temperature, and improve photosynthetic performance.