两种藓类植物对光强的适应性差异

摘要

To explore the adaptive mechanisms of bryophyte plants in Baotianman Nature Reserve,our research determined the photosynthetic characteristics of Thuidium cymbifolium and Mnium immarginatum and revealed a trend of variation with light gradients.Our results showed that M.immarginatum had lower apparent quantum efficiency (AQY),light saturation point (LSP),and light compensation point (LCP) values than T.cymbifolium,indicating that M.immarginatum has a greater ability to adapt to low-light conditions;however,the maximum net photosynthetic rate (Amax) value for T.cymbifotium suggested that it may employ a unique light adaptation strategy.When considering the photosynthetic characteristics of these two species,T.cymbifolium exhibited higher values of water use efficiency (WUE) and stomatal conductance (Gs),which were quite different from intercellular CO2 concentration (Ci) and transpiration rate (Tr).Overall,the results confirmed the hypothesis that a difference in Gs between these two species resulted in adaptation to the environment and represents a survival strategy.%以宝天曼自然保护区两种藓类物种大羽藓(Thuidium cymbifolium)和无边提灯藓(Mnium immarginatum)为研究对象,测定和分析其光合生理特征对于不同光强的响应,探讨藓类植物光适应能力差异的原因,以期为更加合理地保护、利用苔藓植物资源提供理论依据.结果表明,无边提灯藓的表现量子效率(AQY)、光饱和点(LSP)以及光补偿点(LCP)都显著低于大羽藓(P＜0.05),但是大羽藓最大光合速率(Amax)显著高于无边提灯藓,说明无边提灯藓对于弱光生境的适应能力相对较强.进一步从光合参数-光响应过程中分析发现,两种藓类植物的胞间CO2浓度(Ci)和蒸腾速率(Tr)随光照强度变化的趋势基本一致,但大羽藓的水分利用效率(WUE)和气孔导度(Gs)高于无边提灯藓,这从另一个侧面反映出大羽藓独特的光适应策略.综上所述,气孔导度水平的差异可能是最终导致两种藓类植物对于不同光环境适应性不同的原因.