莲叶桐对热带珊瑚岛环境的生理生态适应性

为探究莲叶桐(Hernandia nymphaeifolia)对热带珊瑚岛季节性干旱、强光、盐碱等环境的生理生态适应性,该文对海南省文昌市试验苗圃(以下简称文昌苗圃)和移栽到热带珊瑚岛的莲叶桐的叶片形态解剖结构、抗氧化能力、抗逆渗透物质含量和光合色素等进行了研究。结果表明:(1)与文昌苗圃相比,莲叶桐在移栽到热带珊瑚岛后,比叶面积减小33%,气孔密度下降15%,叶片厚度增加36%,而海绵组织更发达且栅栏组织排列更紧密(厚度分别增加24%和80%),使其能在珊瑚岛环境中更有效地利用光照和水分资源,从而提高光合作用和减少蒸腾作用。(2)移栽到热带珊瑚岛后,莲叶桐的叶绿素含量显著降低86%,而脯氨酸含量、超氧化物歧化酶、过氧化氢酶和过氧化物酶活性却显著升高(分别升高了130%、615%、209%和369%),使其能更好地保护自身光合系统,从而避免岛礁恶劣环境对植物细胞膜透性的破坏。以上结果表明,莲叶桐对热带珊瑚岛干旱、强光、盐碱等环境具有良好的生理生态适应性,可以作为热带珊瑚岛和海滨地区植被恢复的工具种。

Ecophysiological adaptability of Hernandia nymphaeifolia to tropical coral islands

In order to explore the ecophysiological adaptability of Hernandia nymphaeifolia to the tropical coral islands with harsh conditions of seasonal drought, strong light, and saline-alkali soil, we investigated the morphological and anatomical structures, antioxidant capacity, content of osmotic adjustments, and photosynthetic pigments in leaves of H. nymphaeifolia individuals that grown on the experimental nursery in Wenchang City, and that transplanted to the tropical coral islands, Hainan Province. The results were as follows:(1)Compared to H. nymphaeifolia plants grown in the experimental nursery, those plants transplanted to the tropical islands had lower specific leaf area(by 33%)and stomatal density(by 15%), thicker leaf(by 36%), more developed spongy tissue and more closely arranged palisade tissue(by 24% and 80%, respectively), which enable it to make more efficient use of light and water resources, to improve photosynthesis and to reduce transpiration, in the coral island environment.(2)After transplanted to the coral islands, the chlorophyll content of H. nymphaeifolia significantly decreased(by 86%), while proline content, superoxide dismutase, catalase, and peroxidase activity significantly increased(by 130%, 615%, 209% and 369%, respectively), which can protect its photosynthetic system and avoid the damage of plant cell membrane permeability caused by the adverse environment of coral islands. Our results indicated that H. nymphaeifolia had good ecophysiological adaptability to the environment of drought, strong light and saline-alkali soil in tropical coral islands. Therefore, H. nymphaeifolia can be used as a tool species for vegetation restoration on tropical coral islands and coastal areas.