Photosynthetic physiological characteristics of endangered Tsoongiodendron odorum seedlings by high irradiance in summer
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摘要: 以盆栽三年生观光木为试材，利用便携式光合作用测量系统、叶绿素荧光仪及叶圆片氧电极等在夏季对其气体交换特性、叶绿素荧光参数及离体叶片的光合放氧等进行了测定.结果表明，观光木幼树叶片的光补偿点(LCP)为10.1 mol m-2s-1 ，光饱和点约为（LSP）为8 00mol m-2s-1 ，CO2补偿点(CCP)为50.72mol mol-1，CO2饱和点(CSP)为1200mol mol-1.夏季晴好天气下，观光木净光合速率（Pn）的日变化曲线呈双峰型，第1个峰出现在08：00，Pn为9.0molCO2 m-2s-1，第2个峰出现在16：00，Pn为4.6 molCO2 m-2s-1，12：00有明显的光合午休现象.在光合有效辐射较高的时段（10：00至14：00），观光木的Fv/Fm和PSⅡ均处于低水平，特别是在12：00时，PSⅡ光化学效率（Fv/Fm）和PSⅡ实际光化学效率(PSⅡ)降至最低值，表现PSⅡ活性明显下调，观光木叶片光合机构遭受严重的光抑制.观光木PSⅡ活性对强光的敏感性可能是其不耐高光的主要原因之一.
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关键词:
- 光合作用
Abstract: The gas exchange characteristics, chlorophyll fluorescence and photosynthetic oxygen release of Tsoongiodendron odorum seedling (3-year-old, pot-cultured) were measured in summer using a portable photosynthesis system, a PAM chlorophyll fluorometer and a leaf discs oxygen electrode, respectively. The results showed that the light compensation point was 10.1mol m-2s-1, the light saturation point was 800 molm-2s-1, the light compensation point was 50.72 mol m-2s-1, and the saturation point was 1200 molm-2s-1.The diurnal variations of net photosynthetic rate (Pn) presented as a bimodal shape. The first peak was 9.0 molm-2s-1 which appeared at 08:00. The second peak was 4.6molm-2s-1 appearing at 16:00. There was a distinct noon?break phenomenon at 12:00. Both PSⅡphotochemical efficiency (Fv/Fm) and actual photochemical efficiency (PSⅡ) were low during 10:00 to 14:00 when photosynthetic active radiation were high. The Fv/Fm and PSⅡ decreased to the lowest at 12:00, which indicated that the activity of PSⅡ decreased and the photosynthetic?apparatus was severely inhibited by high light. The vulnerable PSⅡ might be a major reason that Tsoongiodendron odorum cannot resist highlight.-
Keywords:
- photosynthesis
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期刊类型引用(6)
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