高温胁迫下根施褪黑素对葡萄叶片叶绿素荧光特性的影响

Effect of root-applied melatonin on photosystem Ⅱ in grape leaves under heat stress

本文以盆栽‘威代尔’葡萄为试验材料,通过测定叶绿素荧光快速诱导动力学曲线、叶绿素荧光淬灭并结合气体交换,分析了高温胁迫下根施褪黑素(melatonin,MT)对葡萄叶片叶绿素荧光特性的影响。结果表明,高温胁迫下,与对照(CK)相比,葡萄叶片净光合速率(P_n)及叶片最大光化学效率(F_v/F_m)均显著下降,OJIP曲线形状发生明显改变,非光化学淬灭(NPQ)显著升高;而根施褪黑素显著缓解了叶片P_n和Fv/F_m的下降,明显降低了高温胁迫下OJIP曲线中K点和J点上升的幅度,增加了叶片对光能的利用效率。上述结果表明,高温胁迫导致葡萄叶片光系统II(PSII)发生较严重的伤害,根施褪黑素能够缓解PSII活性和光合速率的下降程度,改善高温胁迫下葡萄叶片的能量分配。

The potted ＇Vidal Blanc＇ grapevines were used to investigate the effect of root-applied melatonin on photosynthetic characteristics of grape leaves under high temperature. OJIP fluorescence transient, chlorophyll fluorescence quenching and gas exchange parameters were determined. The results showed that Pn （photosynthetic rate） and FJFm （the maximum photochemical efficiency of PSII） were significantly decreased, the shape of the OJIP curve was clearly changed, and NPQ （the non-photochemical quenching） was significantly in- creased under high temperature compared to the CK conditions. In contrast, the root-applied melatonin alleviat- ed the decreases in the parameters of Pn and Fv/Fm, declined the increasing amplitude of the K and J points and enhanced photosynthesis rate clearly under high temperature. Therefore, high temperature stress resulted in a severe damage of PSII, root-applied melatonin alleviated the decreases in photochemistry activity of PSII and photosynthesis rate, improved the energy distribution of grape leaf.