生草覆盖对高温强光下苹果叶片光合特性的影响

Effects of grass coverage on photosynthetic characteristics of apple leaves under high-temperature and high-light conditions

为了揭示高温强光下苹果叶片对不同土壤管理制度的响应机制,以生草覆盖和清耕(对照)条件下的5年生苹果园为试材,采用气体交换和叶绿素荧光动力学技术,研究了生草覆盖对高温强光下苹果叶片光合和荧光参数的影响。结果表明,与清耕相比,高温强光下生草覆盖处理叶片J相相对可变荧光(V j)显著下降,PSⅡ最大光化学效率(F v/F m)显著升高;单位反应中心吸收的光能(ABS/RC)和耗散的能量(DI o/RC)显著降低,用于电子传递的能量(ET o/RC)和捕获的激子将电子传递到还原型原初醌受体下游的其它电子受体的概率(ψo)明显升高,提高了PSⅡ性能指数(PI abs),引起向PSⅠ传递电子的能力增强,从而提高了PSⅠ的活性(ΔI),显著提高了最大净光合速率(P m)。研究表明,高温强光下生草覆盖处理的苹果叶片通过调控能量分配,使光合电子传递流畅,从而维持了较高的光合效率。

In order to reveal responding mechanism of apple leaves trader high-temperature and high-light conditions to different soil manage systems, taking five-year apple trees covered by grass as research object and baring earth as CK, effects of grass coverage on photosynthetic and fluorescence parameters of apple leaves under high-temperature and high-light conditions, by gas exchange and chlorophyll fluorescence kinetics technology. The results show that compared with apple leaves in bare earth under high-temperature and high-light conditions, the relative variable fluorescence at J phase （Vj） of apple leaves in grass covered land is significantly decreased, the maximal quantum yield of primary photochemistry （Fv/Fm） is significantly increased, the electron transport energy per reaction center （ETo/RC）, and the efficiency （ψo） with which a trapped exciton can move an electron into the electron transport chain further than QA- are significantly increased. However, the energy fluxes （per reaction centre） for absorption （ABS/RC） and dissipation （DIo/ RC） are significantly decreased. The significant increase of performance index （PIabs） leads to enhance electron transport ability ofphotosystem （PS） I and improve the activity ofPS I （ΔI）, so the maximum photosynthetic rate （Pm） is significantly increased. The results suggest that grass coverage is able to maintain a high photosynthetic efficiency of apple leaves under high-temperature and high-light conditions, due to the smooth of electron transfer by regulating the specific energy flow.