光强对8种红树植物幼苗叶片气体交换特性的影响

Effects of Light Intensity on Leaf Gas Exchange Characteristics of Seedlings of Eight Mangrove Species

摘要:

为探究红树植物对光强的生理生态适应策略，并指导人工红树林群落不同层次的物种配置，选取常见种无瓣海桑(Sonneratia apetala)、秋茄(Kandelia obovata )、木榄(Bruguiera gymnorhiza)、蜡烛果(Aegiceras corniculatum)、老鼠簕(Acanthus ilicifolius)、卤蕨(Acrostichum aureum)、银叶树(Heritiera littoralis)、黄槿(Talipariti tiliaceum)等8种红树植物为研究对象，通过遮荫控制试验，比较1 a生幼苗在不同生长光强(100%、45%、30%和10%自然光强)下的叶片气体交换参数及水分利用效率和光合氮利用效率。结果表明，木榄、蜡烛果和老鼠簕的净光合速率(P_n)在不同光照强度下没有表现出统计学差异，而秋茄、卤蕨、银叶树和黄槿在45%或30%的光照条件下表现出较高的P_n，说明木榄、蜡烛果和老鼠簕在P_n上表现出对不同光强较好的适应性。秋茄、蜡烛果、银叶树和黄槿在100%光照强度下的气孔导度(g_s)和胞间CO₂浓度(C_i)显著低于遮荫处理。蜡烛果和卤蕨在遮荫条件下的水分利用效率(WUE)显著高于全光照处理，说明蜡烛果和卤蕨的WUE表现出对弱光的适应性。除蜡烛果外的7种红树植物的光合氮利用效率(PNUE)均在遮荫条件下升高。8种红树植物的叶绿素含量随着光照强度的增加而增加，而它们在叶绿素a/b的变化趋势上表现不一。因此，木榄、蜡烛果、老鼠簕和卤蕨较为耐阴，适合在林下种植，而秋茄、银叶树和黄槿则更适合作为中上层树种或在郁闭度较低的林下种植。

Abstract:

To explore the eco-physiological adaptation strategies of mangrove plants to light intensity and guide the species configuration of different layers in artificial mangrove communities, eight common mangrove species, including Sonneratia apetala, Kandelia obovata, Bruguiera gymnorhiza, Aegiceras corniculatum, Acanthus ilicifolius, Acrostichum aureum, Heritiera littoralis, and Talipariti tiliaceum, were selected as research subjects. Through shading control experiments, the leaf gas exchange parameters, water use efficiency (WUE), and photosynthetic nitrogen use efficiency (PNUE) of one-year-old seedlings under different growth light intensities (100%, 45%, 30%, and 10% of natural light intensity) were compared. The results showed that the net photosynthetic rate (P_n) of B. gymnorhiza, Aegiceras corniculatum, and Acanthus ilicifolius did not show statistical differences under different light intensities, while K. obovata, Acrostichum aureum, H. littoralis, and T. tiliaceum exhibited higher P_n under 45% or 30% light conditions, indicating that B. gymnorhiza, Aegiceras corniculatum, and Acanthus ilicifolius showed better adaptability to different light intensities in terms of P_n. The stomatal conductance (g_s) and intercellular CO₂ concentration (C_i) of K. obovata, Aegiceras corniculatum, H. littoralis, and T. tiliaceum under 100% light intensity were significantly lower than those under shading treatments. The WUE of Aegiceras corniculatum and Acrostichum aureum under shading conditions was significantly higher than that under full light conditions, indicating that the WUE of Aegiceras corniculatum and Acrostichum aureum showed adaptability to low light. The PNUE of the seven mangrove species except Aegiceras corniculatum increased under shading conditions. The chlorophyll content of the eight mangrove species increased with the increase of light intensity, but their trends in chlorophyll a/b were different. Therefore, Bruguiera gymnorhiza, Aegiceras corniculatum, Acanthus ilicifolius, and Acrostichum aureum are more shade- tolerant and suitable for planting under the forest canopy, while K. obovata, H. littoralis, and T. tiliaceum are more suitable as middle and upper layer tree species or for planting under a less dense canopy.