不同生长光强下8种红树植物幼苗叶片的光响应特征

Light Response Characteristics of Seedlings Leaves of Eight Mangrove Species Under Different Light Intensities

摘要:

为探讨红树植物光适应的生理生态策略，对6种真红树植物[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)]和2种半红树植物[银叶树(Heritiera littoralis)、黄槿(Hibiscus tiliaceus)]的1 a生幼苗在不同生长光强(自然光强的100%、45%、30%、10%)下的光合光响应特征进行了研究。结果表明，不同生长光强对红树植物光响应特征的影响因物种而异，遮荫显著提高了秋茄和木榄的最大净光合速率(P_max)，而对其他红树植物的P_max没有显著影响；秋茄在45%光强下具有较高的P_max，木榄的P_max则在45%和30%光强下显著高于其他2个处理。随着生长光强的下降，秋茄幼苗叶片的光饱和点显著上升，木榄、老鼠簕和卤蕨的光补偿点呈下降趋势，木榄和卤蕨的表观量子效率升高的同时暗呼吸速率下降。木榄、老鼠簕和卤蕨具有较强的耐荫性，适宜种植在光强较弱的林下；无瓣海桑、秋茄、桐花树、银叶树和黄槿则适宜作为中上层树种或在郁闭度较低的林下种植。

Abstract:

Mangrove species are a group of trees, shrubs or herbs that grow in intertidal zones of tropical and subtropical coasts. They are generally categorized into true mangrove and semi-mangrove species according to their distribution. Understanding the eco-physiological strategies of light adaptation of mangrove species is of important theoretical significance to revealing the community assembly mechanisms of mangrove forests, and can provide scientific guidance for the reconstruction and transformation of mangrove forests. In order to reveal the physiological and ecological strategies to light conditions of mangrove plant species and provide theoretical guidance for optimal assembly of mangrove community structure, the light response characteristics in leaves of eight mangrove seedlings, such as Sonneratia apetala, Kandelia candel, Bruguiera gymnorrhiza, Aegiceras corniculatum, Acanthus ilicifolius, Acrostichum aureum, Heritiera littoralis and Hibiscus tiliaceus, grown under different light intensities, including 100%, 45%, 30%, and 10% of natural sunlight, were studied using shading control experiment. The results showed that the effects of growth light intensities on the photosynthetic light response characteristics were different among mangrove species. Shading significantly increased the maximum net photosynthetic rate (P_max) of K. candel and B. gymnorrhiza, but had no significant effects on P_max of other mangrove species. Kandelia candel had a higher P_max under 45% light intensity treatment, while B. gymnorrhiza had higher P_max under 45% and 30% light intensities. With the decrease of growth light intensity, the light saturation point of leaves of K. candel seedlings significantly increased, the light compensation points of B. gymnorrhiza, Acanthus ilicifolius and Acrostichum aureum appeared a decreasing trend, the apparent quantum yield of B. gymnorrhiza and Acrostichum aureum showed an increasing pattern, and the dark respiration rate of B. gymnorrhiza and Acrostichum aureum decreased. Therefore, it was suggested that B. gymnorrhiza, Acanthus ilicifolius and Acrostichum aureum are suitable for planting under forest with high canopy density, while S. apetala, K. candel, Aegiceras corniculatum, Heritiera littoralis and Hibiscus tiliaceus are suitable to be planted as upper layer species in mangrove forests or planted under forest with low canopy density.