光强在低温弱光胁迫后番茄叶片光合作用恢复中的作用

为了研究光强在低温弱光胁迫后番茄叶片光合作用恢复中的作用，以番茄品种浙粉202为材料，研究了低温弱光后恢复期全光照与遮荫对光合作用和叶绿素荧光参数的影响。结果表明：低温弱光（8℃/12℃，PFD 80 μmol·m^-2·s^-1）导致番茄叶片P_n、Φ_PSⅡ、qP和F_v′/F_m′的下降，但诱导了NPQ的上升，未引起F_v/F_m的变化；全光照（100%光照）下恢复1 使得植株叶片P_n、F_v/F_m、Φ_PSⅡ、qP、NPQ和F_v′/F_m′均大幅下降，随后光合和荧光参数可缓慢恢复至对照水平；遮荫（40%光照）恢复植株F_v/F_m、Φ_PSⅡ和F_v′/F_m′仅在第一天稍有下降，而P_n和qP还略有上升，NPQ虽有所降低但仍显著高于对照水平，随后光合和荧光参数均可迅速恢复到对照水平。说明低温弱光虽抑制了光合作用的进行，但并未引起光抑制的发生；全光照恢复加剧了叶片光抑制的发生，而遮荫恢复可通过叶片PSⅡ光化学活性的快速恢复和天线色素热耗散能力的增强以保护光合机构免受伤害，有利于光合作用的迅速恢复。

The Role of Light Intensity in the Recovery of Photosynthesis in Tomato Leaves after Chilling under Low Light

To investigate the role of light intensity in the recovery of chilled plants, photosynthesis and chlorophyll fluorescence parameters were examined in tomato (Solanum lycopersicum L. cv. Zhefeng 202) plants with natural sunlight or shading during recovery period after chilling under low light. Chilling under low light (8℃/12℃, PFD 80 mol·m^-2·s^-1) significantly decreased the net photosynthetic rate (P_n), the relative quantum efficiency of PSⅡ photochemistry (Ф_PSⅡ), photochemical quenching (qP), and efficiency of energy capture by open PSⅡ reaction centres (F_v′/F_m′), but increased non photochemical quenching (NPQ) and did not induce PSⅡ photoinhibition (F_v/F_m). P_n, F_v/F_m, Ф_PSⅡ, qP, NPQ and F_v′/F_m′ further deceased when the chilled plants were recovered under natural sunlight at 1 and then increased to the values close to the control. However, decreases in these parameters were less significant for shaded plants. Compared with control plants, shaded plants maintained higher NPQ during recovery period. Our results suggested that chilling under low light inhibited photosynthesis, but induced photoinhibition until the plants were exposed to full natural sunlight during recovery period. The photoprotection by shading is associated with the increased photochemical activity of PSⅡ and the enhanced thermal dissipation from antenna in PSⅡ.