干旱胁迫及复水对海滨木槿光合作用和生理特性的影响

选择2年生海滨木槿扦插苗为材料,通过自然干旱20 d而后复水(21 d),研究了其在干旱和复水过程中的光合作用和生理特性.结果表明:经过20 d的干旱胁迫,在土壤含水量仅为5.9%的情况下海滨木槿全部成活,干旱胁迫显著降低了海滨木槿的净光合速率,实测值最高仅为1.1μmol·m^-2·s^-1,最大光化学效率为对照的84.3%.可溶性蛋白和抗氧化酶同时积累,稳定细胞渗透势并清除干旱造成的脂膜过氧化物质.复水7d后光合速率升高至对照的57.3%,超氧化物歧化酶和过氧化氢酶活性随着丙二醛含量下降而下降,复水21 d后,海滨木槿抗氧化酶、可溶性蛋白和叶片相对含水量均恢复至对照水平,干旱处理总生物量虽显著降低,但根冠比显著提高.海滨木槿具有极强的耐旱能力,是适用于沿海地区景观改良和道路绿化的重要树种.

Effects of drought stress and recovery on photosynthesis and physiological characteristics of Hibiscus hamabo

A greenhouse experiment was conducted to examine the photosynthetic and physiological responses of two-year-old cuttings of Hibiscus hamabo to the drought stress (20 days) and subsequent rewatering (21 days). The results showed that after 20-day drought, all individuals were survived in spite of the 5.9% soil water content. Drought stress drastically reduced net photosynthetic rate of H. hamabo, with the highest value only being 1.1 μmol·m^-2·s^-1. Drought stress declined the maximum photochemical efficiency to 84.3% compared with the control plants. Under drought stress, H. hamabo could stabilize cell osmotic potential and eliminate the drought-caused lipid peroxidation by coordinating the accumulation of soluble protein and antioxidant enzymes. After rewatering for seven days, net photosynthetic rate of treated H. hamabo recovered to 57.3% of that under control treatment. Meanwhile, the activities of superoxide dismutase and catalase decreased with the decline of malondialdehyde content. After rewatering for 21 days, no significant differences in the activities of antioxidant enzymes, soluble protein and relative water were found between the treated and control treatment. At harvest, the total biomass of treated H. hamabo decreased, while the root-shoot ratio remarkably increased when compared with control plants. In short, our results indicated strong drought tolerance of H. hamabo, which could play important roles in landscape improvement and greening in coastal areas.