不同遮荫条件下梓叶槭幼苗生长与光合特征的种源差异

Provenance difference in growth traits and photosynthetic characteristics of Acer catalpifolium seedlings under different shading conditions

梓叶槭是我国特有的野生濒危植物,目前尚缺乏对其光合特性及濒危机制的研究.以梓叶槭集中分布地都江堰、大邑、峨眉山和雷波当年生梓叶槭幼苗为材料,分析在遮光率为50%、80%的遮阴条件下幼苗的光合作用能力和生长量.结果表明:不同种源梓叶槭幼苗的净光合速率(P_n)、气孔导度(g_s)、蒸腾速率(T_r)和水分利用效率(WUE)随着光照强度的下降而显著降低.光照强度减弱时,都江堰和峨眉山幼苗光补偿点(LCP)、光饱和点(LSP)均降低,而大邑幼苗均提高,雷波幼苗无显著变化.P_n、WUE与株高和冠幅生长量均呈显著正相关.不同遮光条件下梓叶槭幼苗的光合作用和生长量差异显著,光照不足可能是大邑梓叶槭幼苗林下自然更新的限制因子.雷波地区梓叶槭幼苗较其他地区幼苗喜荫,而都江堰和峨眉山幼苗具有较好的光适应能力,生长性状表现良好,可作为移植保护的优质种源.

Acer catalpifolium is a unique species and wild endangered one in China.Currently,no research has addressed its endangered status from the perspective of photosynthetic characters.The photosynthesis characteristics and growth rate of A.catalpifolium seedlings from four provenances（Dujiangyan,Dayi,Emeishan and Leibo）under two shading conditions（50% and 80% of full shade）were examined to explore the light response mechanism.The results showed that the net photosynthetic rate（Pn）,stomatal conductance（gs）,transpiration rate（Tr）and water use efficiency（WUE）of A.catalpifolium seedlings from four provenances sharply decreased with the decreases of light intensity.When the light intensity was reduced,the light compensation point（LCP）and light saturation point（LSP）of A.catalpifolium seedlings from Dujiangyan and Emeishan were all decreased,while those of the seedlings from Dayi increased,and those of the seedlings from Leibo showed no significant changes.Net photosynthetic rate and water use efficiency were positively correlated with plant height and crown growth.The effects of different light intensities on photosynthetic characteristics and growth rate of A.catalpifolium were significantly different.Low light availability under canopy might be the limiting factor for natural regeneration of A.catalpifolium populations from Dayi.Compared with other provenances,A.catalpifolium seedlings from Leibo were more shade requiring.A.catalpifolium had better light adaptability and growth performance from Dujiangyan and Emeishan,which could be used as high-quality source for transplant protection.