西沙群岛草海桐的抗逆生物学特性

热带珊瑚岛由于光照强、季节性干旱明显、土壤贫瘠、保水能力差而少有植物生长。草海桐(Scaevola sericea)是一种典型的热带滨海植物,是西沙群岛珊瑚岛植被中的主要建群种,在海岛和海岸带防风固沙及植被生态恢复等方面发挥着重要作用。该研究对西沙群岛自然环境下草海桐的形态解剖学特征、抗氧化能力、抗逆性物质含量及营养元素含量等进行了研究。结果表明:草海桐具有阳生性植物特征,叶片及上表皮厚、气孔密度小、导管直径及水力导管直径大,有利于其适应珊瑚岛干旱环境; 其体内的超氧化物歧化酶和过氧化氢酶活性与其他受胁迫植物相比较要高,脱落酸含量也较高,表明草海桐对珊瑚岛环境具有较强的适应性及抗逆性; 其根际土壤养分含量偏低,但植物体内营养元素含量却较高,表明草海桐对土壤养分的利用效率高。这说明草海桐能够很好地适应干旱、贫瘠的珊瑚砂环境,具有较强的抗逆及适应能力。

Stress resistance biological characteristics of Scaevola sericea in Paracel Islands

There are few plants in tropical coral islands because of hard light, obvious seasonal drought, barren soil and poor water retention capacity of soil. As a typical coastal plant species and the main constructive species of coral island vegetation in Paracel Islands, Scaevola sericea plays important roles in sand-fixation, wind resistance and ecological restoration on the vegetation of islands and coastal zones. In this study, we analyzed the morphological and anatomical characteristics, antioxidant capacity, resistant substance contents and nutrient compositions of S. sericea growing in the natural habitat in Paracel Islands. The results showed that S. sericea was a heliophyte with thick leaf and epicuticle, low stomatal density and large vessel diameter and hydraulically weighted vessel diameter, which helps S. sericea adapt to the drought, high temperature and intense light irradiation. The activities of superoxide dismutase and catalase were higher than those of other plants under stress, and the high content of abscisic acid in the leaves revealed that S. sericea had strong adaptability and resistance. The contents of nutrient elements in the leaves of S. sericea were higher than those in rhizosphere soil, indicating that S. sericea has strong stress resistance and good adaptability to the arid and barren environment.