低磷胁迫对油菜不同生育期叶片光合作用的影响

Effects of Low Phosphorus Stress on Photosynthesis of Rapeseed Leaves in Different Periods

油菜是中国的主要油料作物之一,对低磷胁迫敏感。土壤缺磷是油菜获得高产的重要限制因子。通过气体交换参数和荧光诱导动力学参数的测定和分析,研究了低磷胁迫对油菜不同生育期光合特性、叶绿素荧光参数及能量分配的影响。结果表明:与对照相比,低磷处理明显降低了油菜蕾薹期、花期的净光合速率(Pn);油菜三个生育期的最大荧光(Fm)、可变荧光(Fv)、最大光化学效率(Fv/Fm)没有显著下降,表明低磷处理没有影响到油菜叶片的原初反应中心;但是,低磷胁迫使油菜蕾薹期光系统Ⅱ(PSⅡ)量子产量(ФPSⅡ)、电子传递速率(ETR)、光化学猝灭系数(qP)显著下降,非光化学猝灭系数(NPQ)显著上升,能量分配方面天线热耗散(D)和PSⅡ反应中心过剩激发能(Ex)上升,PSⅡ光化学反应(P)下降,表明低磷胁迫导致油菜蕾薹期PSⅡ电子传递受阻,油菜植株启动了能量耗散途径应对低磷胁迫。

As one of the most important oilcrops,rapeseed is sensitive to low phosphorus stress.And the lack of phosphorus in the soil is one of the major constraint factors for rapeseed to achieve a high yield in agricultural production.Gas exchange parameters and chlorophyll fluorescence quenching kinetics were investigated to explore the effect of low phosphorus stress on photosynthesis,chlorophyll fluorescence characterisitics and energy distribution in rapeseed during different developing period.The results showed that Pn was obviously decreased in stem elongation and flowering stage,while Fm、Fv and Fv/Fm remained unchanged during three developing periods,indicating that PSⅡ primary reaction centres were not affected by low phosphorus stress.However,ФPSⅡ、ETR、qP were obviously decreased and NPQ was obviously increased under the low phosphorus stress.In the aspect of excitation energy distribution,both D and Ex increased while P declined obviously.It suggested that the pathway of electron transport through PSⅡ was blocked,In this case,the plant of rapeseed had triggered the pathway of energy dissipation to respond the low phosphorus stress.