七种热带雨林树苗叶片气孔特征及其可塑性对不同光照强度的响应

Response of stomatal characteristics and its plasticity to different light intensities in leaves of seven tropical woody seedlings

对生长在荫棚 3种不同光照条件下和全自然光下的热带雨林 4个冠层种 (望天树、绒毛番龙眼、团花、红厚壳 )和 3个中层种 (玉蕊、藤黄、滇南风吹楠 )树苗叶片气孔特征以及它们的可塑性进行了研究 .结果表明 ,这些植物的气孔全部着生在远轴面 .7种植物中 ,玉蕊和绒毛番龙眼的气孔密度较大 ,滇南红厚壳和团花的保卫细胞最长 .随光强的增大 ,气孔密度和气孔指数增大 ,单位叶气孔数在低光强下较大 .除团花外 ,其它植物叶片气孔导度在 5 0 %光强处最大 ,而光强对保卫细胞的长度影响不显著 .相关分析表明 ,气孔密度与植物单位叶的面积呈负相关 ,而与气孔导度的相关性不显著 .尽管两种不同生活型植物气孔指数和单位叶气孔数在不同光强下的可塑性差异较小 。

Stomatal characteristics and its plasticity in leaves of four canopy species, Shorea chinensis, Pometia tomentosa, Anthocephalus chinensis, Calophyllun polyanthum and three middle-layer species, Barringtonia pendula, Garcinia hanburyi, Horsfieldia tetratepala acclimated to different light conditions (8%, 25%, 50% and 100% of full sunlight) for more than one year were surveyed. All plant's stomata were distributed on the abaxial of leaves. Pometia tomentosa and Barringtonia pendula had higher stomatal density, and the guard cell length of Anthocephalus chinensis and Calophyllun polyanthum were much greater than others'. Stomatal density and stomatal index (ratio of stomatal numbers to epidermal cell number) were increased with growth irradiance increased, while numbers of stomata per leaf were higher in the low than the high relative PFD, and stomatal conductance of leaves was the highest in the 50% of sunlight except for Anthocephalus chinensis. The relative PFD had little effects on the guard cell length of all seven plants. There was a significant negative correlation between stomatal density and leaf area, but the stomatal conductance was not significantly positive with the stomatal conductance in some degree. The analysis of phenotypic plasticity of stomatal characteristics showed that plasticity index for stomatal index and numbers of stomatal per leaf were similar for canopy and middle-layer species, while the plasticity index of stomatal density and stomatal conductance were significantly greater for canopy species than middle-layer species. The high plasticity of canopy species was consistent with the hypothesis that specialization in a more favorable environment increases plasticity.