几种南亚热带木本植物光合作用对生长光强的响应

Response of Photosynthesis to Growth Light Intensity in Some South Subtropical Woody Plants

摘要:

分别将马尾松（Pinus massoniana）、黧蒴（Castanopsis fissa）、荷木（Schima superba）、黄果厚壳桂（Cryptocarya concinna）的幼苗置于100％自然光和32％自然光下生长6个月，测定它们的光强-光合反应曲线和叶绿素荧光的某些参数。结果表明，在100％光下，马尾松有最高的最大光合速率（Pmax）、光饱和点（LSP）、光补偿点（LCP）、暗呼吸（Rd）、表观量子效率（AQY）和总电子传递速率（JF），光化学猝灭（qP）也最大。而黄果厚壳棒有最大的分配到光呼吸的电子流比率（JO/JF）。100％光下AQY的大小顺序为：马尾松〉黧蒴〉荷木〉黄果厚壳桂，32％光下AQY的顺序则相反。这说明群落早期演替的先锋树种马尾松属于强阳生性树种，具有适应强光的特点，而处于群落演替项级阶段的优势种黄果厚壳梓则能更加充分利用低光生长环境中的光强，同时也可通过提高电子流向光呼吸分配的比例来避免自然光环境中强光的伤害。

Abstract:

One-year-old seedlings of four woody dominant species of different succession stages from south subtropical forest were potted under 100% and 32% of natural light for six months. Light response curve of photosynthesis and some parameters of chlorophyll fluorescence in these species were determined. Under 100% of natural light, Pinus massoniana had highest values of maximum photosynthetic rate （Pmax）, light saturation point （LSP）, light compensation point （ LCP）, dark respiration rate （Rd）, the apparent quantum yield （AQY）, leaf total electron flow rate （JF） and photochemical fluorescence quenching （qP）, whereas Cryptocarya concinna exhibited maximum fractions of total electron flow partitioned to photorespiration （JO/JF）. AQY under 100% of natural light was in the order of Pinus massoniana 〉 Castanopsis fissa 〉 Schima superba 〉 Cryptocarya concinna, while the result was the reverse under 32% of natural light. These suggest that Pinus massoniana, the pioneer species at early succession stage of forest community, is the plant species adapted to high light intensity, while Cryptocarya concinna, a species at succession climax stage has an advantage in light utility under low light environment. The results also support that the increasing ratio of total electron flow allocation to photorespiration in Cryptocarya concinna is one of the strategies to protect itself against high light damage.