半红树植物杨叶肖槿和海芒果的光合特性研究

摘要

Thespesia populnea and Cerbera manghas, two semi-mangrove species with medicinal and ornamental values, play important roles in coastal ecosystems. In this paper, we examine the photosynthetic characteristics of the two species, including specific leaf areas, chlorophyll contents, chlorophyll fluorescence parameters, and photosynthesis-light response curves. Light saturation point (LSP) and light compensation point (LCP) ofT. populnea were 519.301 and 42.178μmol·m-2·s-1 respectively; and LSP and LCP ofC. manghaswere 268.287 and 29.862μmol·m-2·s-1 respectively. Therefore,T. populnea and C. manghas are typical heliophyte and mesophyte species.T. populnea had higher photochemical fluorescence quenching (NPQ, 2.264) and instantaneous water use efficiency (IWUE, 9.640μmol·mmol-1), indicating higher photo-protection and water use capacities in high-light conditions. When light intensity was higher than LSP, the photosynthetic rate ofT. populnea did not decline, suggesting stronger resilience to high-temperature and high-light intensity. With higher specific leaf area (SLA, 99.07 cm2·g-1) and chlorophyll a/b ratio (3.519)C. manghas could effectively absorb and transform light energy in low-light environments, thus could better adapt to low-light intensity environment. These results showed that in coastal zone greening,T. populnea can be a pioneer species, whileC. manghas could be cultivated with heliophyte plants or be planted at forest edges.%杨叶肖槿（Thespesia populnea）和海芒果（Cerbera manghas）是2种有较高药用价值和园林价值的半红树植物，在海岸带生态系统中发挥着重要作用。测定了这2种半红树植物的比叶面积、叶绿素含量、叶绿素荧光参数、光响应曲线等光合特征指标。结果表明：杨叶肖槿的光饱和点（LSP）和光补偿点（LCP）分别为519.301和42.178μmol·m-2·s-1；海芒果的光饱和点（LSP）和光补偿点（LCP）分别为268.287和29.862μmol·m-2·s-1，杨叶肖槿和海芒果分别属于典型阳生植物和中生植物。比较2种半红树植物光合特性发现：杨叶肖槿具有较高的非光化学荧光淬灭（NPQ，2.264）和瞬时水分利用效率（IWUE，9.640μmol·mmol-1），这表明杨叶肖槿在强光下的光保护能力和水分利用能力更强；在高于光饱和点的光强下，杨叶肖槿叶片光合速率未出现下降趋势，对高温和强光照的适应能力更强。海芒果具有较高的比叶面积（SLA，99.07 cm2·g-1）、叶绿素a/b比值（3.519），能在低光环境中有效吸收和转化光能，对低光环境有较强的适应力。上述结果表明，在海岸带绿化中，杨叶肖槿可作为先锋树种种植，而海芒果则需要与阳生植物搭配种植或种植于林缘。