光胁迫下杂种杨无性系光合生理生态特性的研究

ECOPHYSIOLOGICAL CHARACTERISTICS OF PHOTOSYNTHESIS OF HYBRID POPLAR CLONES UNDER LIGHT STRESS

以气体交换测定结合叶绿素荧光技术对几个杂种杨新无性系在自然光胁迫下的光合生理生态特性进行分析。８月ＣＯ２气体交换测定显示，中午存在明显的光合作用下降现象，同时某些无性系中午的气孔导度也有不同程度下降。叶绿素荧光分析显示，强光胁迫会影响光合作用的原初光化学反应过程，光系统Ⅱ（ＰＳＩＩ）反应中心的最大光化学量子产率，有效光化学量子产率等反映光系统Ⅱ反应中心活性的参数值在中午均比早晨低。与此同时，光系统Ⅱ反应中心的非光化学淬灭上升，他是光系统Ⅱ反应中心的一种自我保护机制。参数（Ｆｍ－Ｆｍｒ）／Ｆｍｒ、１—ｑｐ／ｑＮ和（Ｆ’ｍ－Ｆ）／Ｆ’ｍ可以反映各个无性系发生光抑制的可能性大小。由此计算出的各无性系发生光抑制的可能性排列次序与气体交换法测定的结果是一致的。

The ecophysiological characteristics of photosynthesis of several new triploid and diploid clones of Populus were investigated under natural light using both chlorophyll fluorescence and gas exchange techniques. In August measurements a substantial midday depression of photosynthesis and mild decrease in stomatal conductance was observed in clones. The efficiency of PSII center for each clones decreased around noon, indicating that the PSII complex was inactivated when subjected to light stress at this time. Meanwhile nonphotochemical quenching of PSII center, was also high around noon. This process enables the PSII center to dissipate excessive light and may prevent photo-damage. Photoinhibitory susceptibility is assessed using three indicators: (Fm-Fmr), 1-qP /qNand (Fm-F)/Fm.