贵州喀斯特森林三种植物对不同坡位环境的光合生理响应

Photosynthetic physiological response of three plant species to different slope environments in karst forest of Guizhou, China

关键词:  植被恢复, 碳酸酐酶, 表观量子效率, 羧化效率, 稳定碳同位素组成

Key words:  revegetation, carbonic anhydrase, apparent quantum efficiency, carboxylation efficiency, composition of stable carbon isotope

摘要:

该研究以贵州普定喀斯特森林中、下坡位生长的构树(Broussonetia papyrifera)、朴树(Celtis sinensis)和光滑悬钩子(Rubus tsangii)为材料,通过对碳酸酐酶(CA)活性、光合作用日变化、净光合速率对CO₂与光的响应曲线、叶绿素荧光特性以及稳定碳同位素组成等指标的测定,进而对比分析三种植物不同的光合生理响应特性。结果表明:构树光合作用过程的无机碳源既可来自大气中的CO₂,也可以在气孔部分闭合的情况下利用细胞内的HCO₃^-,下坡位的构树较高的CA活性使其利用HCO₃^-的效率会更高,并能在较低光强下具有较高的光能利用效率。这可能与下坡位的构树具有较高的CA活性有关,对下坡位具有更好的适应性。朴树光合无机碳的同化能力最低,且光合无机碳源较单一,主要利用大气CO₂,其较慢的生长速率使其对无机碳的需求最低,且能保持较稳定的无机碳同化速率。相对来说,中坡位的朴树具有相对较高的净光合速率和光能利用效率,对中坡位表现出较好的适应性。光滑悬钩子主要利用大气中的CO₂进行光合作用。中坡位的光滑悬钩子具有较强的光能利用效率,并表现出较高的净光合速率,光滑悬钩子对中坡位同样表现出较好的适应性。该研究结果为喀斯特生态脆弱区植被重建过程中树种的选择及合理配置提供了科学依据。

Abstract:

In order to gain a better understanding on the different adaptive characteristics of karst plants and to develop reasonable vegetation we studied the carbonic anhydrase(CA)activity, diurnal variation of photosynthesis, response curves of net photosynthetic rate of CO₂ concentration and light intensity, chlorophyll a fluorescence parameters and stable carbon isotope composition of Broussonetia papyrifera, Celtis sinensis and Rubus tsangii which grew in the middle and lower slopes of the karst forest in Puding County, Guizhou Province. Their different photosynthetic physiological response of the three species were also analyzed. The results indicated that in the photosynthesis, B. papyrifera could utilize the atmospheric CO₂ and the intracellular HCO₃^- through the catalysis conversion by CA when the stomatal conductance decreased. With higher activity of CA, B. papyrifera growing in the lower slope had higher HCO₃^-utilization efficiency. Besides, B. papyrifera growing in the lower slope exhibited higher light utilization efficiency under low light intensity, which might be attributed to its higher CA activity in the lower slope. B. papyrifera showed better adaptability to lower slope compared to middle slope. The photosynthetic inorganic carbon assimilation efficiency of C. sinensis was the lowest, which only used the atmospheric CO₂ as inorganic carbon resource for the photosynthesis. Since the growth rate of C. sinensis was very slow, the requirement for inorganic carbon was the lowest, and it could maintain the stable inorganic carbon assimilation rate. C. sinensis growing in the middle slope exhibited higher net photosynthetic rate and light utilization efficiency, and it showed better adaptability to the middle slope compared to lower slope. R. tsangii mainly utilized the atmospheric CO₂ in the photosynthesis process. The light utilization efficiency and net photosynthetic rate of R. tsangii in the middle slope were higher. R. tsangii exhibited better adaptability to middle slope. The results provide a scienti-fic basis for reasonably selecting and designing plant species during the revegetation process in the karst ecologically vulnerable forest region.