遮荫对8种红树植物幼苗叶片叶绿素荧光参数的影响

Effect of Shading on Chlorophyll Fluorescence Parameters in Leaves of Seedlings of Eight Mangrove Species

摘要:

为探讨红树植物光适应的生理生态机制，通过遮荫控制试验对无瓣海桑(Sonneratia apetala)、秋茄(Kandelia candel)、木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、老鼠簕(Acanthus ilicifolius)、卤蕨(Acrostichum aureum)、银叶树(Heritiera littoralis)、黄槿(Hibiscus tiliaceus)等8种红树植物的1 a生幼苗在不同生长光强(自然光强的100%、45%、30%、10%)下的叶绿素荧光参数进行了研究。结果表明，8种红树植物在遮荫后光系统Ⅱ最大光化学效率(F_v/F_m)和光系统Ⅱ实际光化学效率(ΦPSII)总体呈上升趋势，而电子传递速率(ETR)则显著下降。无瓣海桑、秋茄、桐花树、银叶树和黄槿在全光照下表现出比其他3种植物更高的F_v/F_m，同时桐花树和银叶树的ΦPSII和ETR也显著高于木榄、老鼠簕和卤蕨。因此，无瓣海桑、秋茄、桐花树、银叶树和黄槿在高光辐射下具有更高的光能利用率，同时桐花树和银叶树能更好地利用高光并耗散过剩光能，适宜作为中上层树种或在郁闭度较低的林下种植。而木榄、老鼠簕和卤蕨在高光辐射下ΦPSII值均不足0.2，ETR也仅为无瓣海桑等阳生物种的20%~33%，更适宜在光照条件较弱的林下种植。

Abstract:

The restoration and reconstruction of mangrove wetland ecosystems is one of the key research fields in ecological restoration in the coastal zones of South China. How to optimize the assembly of mangrove species is the priority to be concerned in the restoration and transformation of mangrove forest community. In order to reveal the ecophysiological strategies to light conditions of mangrove plant species and provide theoretical guidance for optimal assembly of mangrove community structure, the characteristics of leaf chlorophyll fluorescence parameters in seedlings of eight mangrove plant species, such as Sonneratia apetala, Kandelia candel, Bruguiera gymnorrhiza, Aegiceras corniculatum, Acanthus ilicifolius, Acrostichum aureum, Heritiera littoralis and Hibiscus tiliaceus, under different light intensities (100%, 45%, 30%, and 10% of natural sunlight) were studied using shading control experiment. The results showed that all of eight mangrove plant species appeared a significantly higher maximal photochemical efficiency of PSII (F_v/F_m) and actual photochemical efficiency of PSII (ΦPSII) in shading treatments, while the significant lower electron transport rate (ETR) was found in shading treatments in seedlings of eight mangrove species. Under 100% light intensity, S. apetala, K. candel, A. corniculatum, Heritiera littoralis and Hibiscus tiliaceus had higher F_v/F_m than the other three mangrove plant species, while A. corniculatum and Heritiera littoralis had higher ΦPSⅡ and ETR than B. gymnorrhiza, A. ilicifolius and A. aureum. Therefore, Sonneratia apetala, K. candel, A. corniculatum, Heritiera littoralis and Hibiscus tiliaceus had high light energy utilization, while A. corniculatum and Heritiera littoralis could make better use of high light and dissipate excess light energy to protect photosynthetic organs, thus these five mangrove species are suitable to be planted as upper layer tree species in mangrove forests. In contrast, the ΦPSII of B. gymnorrhiza, A. ilicifolius and A. aureum were lower than 0.2, and ETR was only 20%-33% of those of sun plant species like S. apetala, indicating that they are suitable to be used as understory species in dense mangrove forests.