光胁迫对沙冬青叶绿素荧光特征和光呼吸的影响

Effect of Light Stress on Chlorophyll Fluorescence and Photorespiration of Ammopiptanthus mongolicus

使用LI-6400测定乌兰布和沙漠东北缘的沙冬青在不同光合有效辐射下的叶绿素荧光特征和光呼吸变化,进而研究其光破坏防御特征的变化。结果表明,PSⅡ最大光化学量子产量(Fv/Fm)可作为衡量沙冬青光胁迫程度大小指标,有效光化学量子产量(Fv′/Fm′)、总光合速率(Pt)、非光化学猝灭(qN)、光呼吸速率(Rp)和Rp/Pt等指标的光进程曲线临界点值和临界点光强度与Fv/Fm的关系都具有明显的规律性。随着Fv/Fm降低,光胁迫程度增加,导致沙冬青光胁迫的最小光合有效辐射降低。可见,沙冬青光破坏防御的一种策略是在胁迫程度较小时通过提高热耗散和光呼吸相对比值(Rp/Pt)来消耗过剩能量,而在胁迫程度较大时可通过增加抑制热耗散和光呼吸的光合有效辐射实现对过剩光能的消耗。

Based on measuring the chlorophyll fluorescence and photorespiration of Ammopiptanthus mongolicus under different light intensity by LI-6400,the photoprotection of Ammopiptanthusmon golicuswas studied in the northeast of Ulan Buh Desert.The results showed that the maximal quantum yield of PSⅡ photochemistry（Fv/Fm）could be used as the index to evaluate the light stress.Fv/Fmwas obviously related to the critical points in the course curve of the chlorophyll fluorescence indexes,such as the maximal at（Fv′/Fm′）,total photosynthetic rate（Pt）,non-photochemical quenching（qN）,photorespiration rate（Rp）,Rp/Ptto the light intensity,etc.With the decline of Fv/Fm,the degree of light stress increased and the minimum light intensity of light stress decreased.The result showed that one of strategy for photoprotection of Ammopiptanthusmongolicuswas that it exhausted superfluous energy by improving Rp/Ptsurplur when stress was smaller,and consumed excess light energy by increasing light intensity of inhibiting thermal dissipation and photorespiration.