珍稀濒危植物堇叶紫金牛对持续干旱的生理响应

采用盆栽控水法,研究了珍稀濒危植物堇叶紫金牛(Ardisia violacea)在持续干旱条件下的生理响应。随着持续干旱时间的延长,堇叶紫金牛应对持续干旱的阶段可分为适应期、轻度干旱期、中度干旱期和重度干旱期。在适应期和轻度干旱期,堇叶紫金牛叶片游离脯氨酸和可溶性糖含量稳定在一个较低水平,可溶性蛋白质含量先下降后快速上升,细胞膜系统和抗氧化酶系统能主动进行生理调节;中度干旱期,丙二醛(MDA)含量和质膜相对透性迅速升高,细胞膜系统受损加剧,游离脯氨酸、可溶性糖含量均急剧增加,对抵御干旱起到重要的渗透调节作用。在轻度干旱期和中度干旱期,光合色素中叶绿素a和叶绿素b含量显著提高,以抵抗干旱胁迫。重度干旱期,细胞膜系统、抗氧化酶SOD、游离脯氨酸和可溶性糖含量上升,但MDA略微下降,这时可能达到植物耐受干旱的极限,不再发生膜脂过氧化作用。综上表明,堇叶紫金牛具有较强的耐旱性,RWC为49.94%是细胞膜系统、抗氧化酶系统和渗透调节物质含量变化的拐点,渗透调节和抗氧化酶系统的主动适应是其耐旱的主要机制。

Physiological responses of the rare and endangered Ardisia violacea (Myrsinaceae) seedlings to progressive drought stress

In this paper, water controlling experiment was used to measure the physiological responses of Ardisia violacea. The results show that: with the prolonged drought stress, the soil water content decreased gradually. There are four stages of A. violacea''s response to drought stress, including adaptation period, mild drought stress period, moderate drought stress period and severe drought stress period. Under adaptation period and mild drought stress period, the content of free proline and soluble sugar stabilized at a low level while the soluble protein content decreased and then increased rapidly, and the membrane systems and antioxidant enzyme systems can conduct physiological regulation. Under moderate drought stress period, malondialdehyde and membrane permeability increased rapidly, and membrane system was damaged. The content of free proline and soluble sugar increased remarkably, which act as a key role in resist drought stress. Photosynthetic pigments including hlorophyll a and chlorophyll b significantly increased during the mild and moderate drought stress periods in order to resist drought stress. Under serve drought stress period, the membrane systems, SOD, free proline and soluble sugar increased, but MDA decreased, which means the plant reached the tolerable limit and no more membrane lipid peroxidation. In summary, 49.94% of RWC is the turning point of membrane system, antioxidant enzyme systems and osmotic adjustment substances. The active adaptation of osmotic adjustment and antioxidant enzyme systems is the main mechanism of its drought tolerance. A. violacea has strong drought resistance.