水氮处理对岛礁植物假茉莉生理适应性的影响

为了解假茉莉(Clerodendrum inerme)对热带珊瑚岛礁的生理适应性,采用不同浇水频率和氮素处理,对假茉莉的光合特性及抗逆生理生化特性进行了研究。结果表明,不同浇水频率对于假茉莉生理特性影响较大,而不同氮素处理间的差异不大,说明假茉莉对水分胁迫更加敏感。在低浇水频率下,假茉莉叶绿素a含量和叶绿素a/b最高,且与其他浇水频率间的差异显著,净光合速率、气孔导度、水分利用率均显著高于高浇水频率,而蒸腾速率显著低于高浇水频率,表现出较好的光合同化效率和水分利用效率;中等浇水频率的脯氨酸含量最高,为(5.04±1.21)mg/g,可降低植物体的渗透压,保证干旱胁迫下对水分的吸收。低浇水频率的相对电导率最低,为0.17±0.03,可减少干旱胁迫对细胞膜系统的损伤。因此,假茉莉对干旱、贫瘠的热带珊瑚岛礁生境具有很好的适应能力。

Effects of Water and Nitrogen Treatment on Physiological Adaptability of Island Reef Plant Clerodendrum inerme

In order to understand the physiological adaptability of Clerodendrum inerme to tropical coral islands, the photosynthetic and stress resistance characteristics of C. inerme were studied under different water and nitrogen treatments. The results showed that watering frequency had greater effects than nitrogen treatment on physiological characteristics of C. inerme. The chlorophyll (Chl) a content and Chl a/b were the highest under low watering frequency with significant difference under other watering frequencies. The net photosynthetic rate (P_n), stomatal conductance (G_s) and water use efficiency (WUE) under low watering frequency were significantly higher than those under high watering frequency, while the transpiration rate (T_r) was significantly low, showing better photosynthetic capacity and water use efficiency. The proline (Pro) content under medium watering frequency was the highest with (5.04±1.21) mg/g, which could reduce the osmotic pressure and increase water absorption under drought stress; the relative conductivity under low watering frequency was the lowest with 0.17±0.03, which could reduce membrane system damage caused by drought stress. Therefore, Clerodendrum inerme has a good adaptability to drought and barren habitats in tropical coral islands.