高温强光下水杨酸对黄瓜叶片叶绿素荧光和叶黄素循环的影响

在高温强光条件下，研究了外源水杨酸对黄瓜叶片叶绿素荧光参数和叶黄素循环的影响.结果表明，在高温强光胁迫前2 d用50～400 μmol·L^-1水杨酸处理叶片，抑制了高温强光下原初光能转换效率(F_v/F_m)、光合电子传递量子效率(ΦPSⅡ)、最大荧光(F_m)和光化学猝灭系数(qP)的下降，分别比对照提高了16.1%～30.2%、11.9%～33.0%、7.2%～41.0%和27.2%～160.8%，促进了非光化学猝灭系数(NPQ)的升高，比对照提高了13.1%～62.9%，而对初始荧光(F_o)影响不大.水杨酸处理可减小高温强光下叶黄素循环库的下降幅度，使(A+Z)/(V+A+Z)升高，分别比对照高29.5%和24.6%.这些结果说明，水杨酸可通过提高非辐射能量耗散,对高温强光引起的黄瓜叶片光合机构的破坏具有保护作用.

Effects of salicylic acid on chlorophyll fluorescence and xanthophyll cycle in cucumber leaves under high temperature and strong light

In this study, cucumber leaves were under high temperature and strong light stress after two days of spraying with 50 to approximately 400 micromol x L(-1) salicylic acid (SA) solution. The measurements showed that SA pretreatment could inhibit the decrease of intrinsic photochemical efficiency (Fv/ /Fm), quantum yield of PSII(phiPSII), maximum fluorescence value (Fm), and photochemical quenching (qP) by 16.1% to approximately 30.2%, 11.9% to approximately 33.0%, 7.2% to approximately 41.0% and 27.2% to approximately 160.8%, respectively, and promote the increase of non-photochemical quenching (NPQ) by 13.1% to approximately 62.9%, but had little effect on initial fluorescence value (Fo). SA pretreatment could also inhibit the decrease of xanthophyll cycle pool in cucumber leaves, and increase the de-epoxidation extent of xanthophyll cycle (A + Z)/(V + A + Z),which was 29.5% and 24.6% higher than control, respectively. It was suggested that SA could protect the photosynthetic apparatus of cucumber leaves under high temperature and strong light through promoting non-radiative energy dissipation.