天台山3种常绿阔叶树光合特性的季节变化

Seasonal Variations of Photosynthetic Characteristics of 3 Evergreen Broad-leaved Species in Tiantai Mountains

以天台山东南石栎、云锦杜鹃和甜槠 3 种常绿阔叶树为材料,对其光合特性的季节变化进行了研究,结果表明:(1)在夏季,东南石栎等 3 种常绿阔叶树的光合日变化均为双峰型,具有明显的光合午休现象。(2)日均净光合速率大小的季节顺序为夏季>秋季>春季>冬季,树种顺序为东南石栎>甜槠>云锦杜鹃。(3)东南石栎等常绿树种日均净光合速率比大血藤等层间植物和七子花等落叶植物高。(4)在夏季,3 种常绿树种的光补偿点最低,光饱和点最高。(5)3 种常绿阔叶树叶绿素含量夏季最高,叶绿素 a / b 值夏季最低。同种植物叶绿素含量季节变化与净光合速率有一定的相关性,与光饱和点呈正相关,与光补偿点呈负相关。

Studies were carried out on seasonal variations of photosynthetic characteristics of three evergreen broad-leaved species in Tiantai Mountains, Zhejiang province, including Lithocarpus harlandii, Rhododendron fortunei, Castanopsis eyeri. The results showed that: 1) In summer the diurnal variations of net photosynthetic rates (Pn) of the three species were all “twin-peaked”, with obvious “midday-depression” of photosynthesis. 2) The values of average daily Pn were summer>autumn>spring>winter by season, and L. harlandii>C. eyeri>Rh. fortunei by species. 3) Average daily Pn of the three evergreen broad-leaved species were higher than layer species such as Sargentodoxa cuneata and deciduous species such as Heptacodium miconioides. 4) The light compensation points (LCP) of the three species were lowest in summer, and their light saturation points (LSP) were highest. 5) The chlorophyll contents of the three species topped in summer, and a/b of chlorophyll were the lowest. There was certain relation between chlorophyll contents and Pn in the same species. The seasonal variations of chlorophyll contents in leaves of the same species were positively related to LSP, but negatively to LCP.