不同盐度对鱼藤幼苗生长及光合作用的影响

Effects of different salinities on the growth and photosynthesis of Derris trifoliata seedlings

鱼藤（Derris trifoliata）是红树林常见伴生藤本植物。为了解其对潮间带高盐生境的响应和适应，研究了0～40的盐度对鱼藤幼苗生长、光合和叶绿素荧光的影响。结果表明：1）盐度低于20处理，幼苗生长相对较快；2）随盐度升高，根冠比下降、地下部分生物量受到影响大于地上；3）随盐度升高，净光合速率（砌）、蒸腾速率（聊和气孔导度（Gs）呈显著下降趋势；胞间CO2浓度（CO先降低后升高，盐度为20时达到最小值；Tr和气孔限制值（Ls）与Ci趋势相反；PSⅡ实际光化学量子产量显著下降，非光化学淬灭系数趋势与之相反。综上表明，盐胁迫对鱼藤幼苗生长、光合和叶绿素荧光均有影响，盐度越高，抑制越明显；低盐（盐度低于20）利于鱼藤幼苗生长。

Derris trifoliata is a vine plant that commonly grows in the edges of mangroves in China. In order to understand its response and adaptability to salt stress in inter-tidal habitats, we manipulated 0-40‰ salinities on the seedlings of D. trifoliata, and investigated the growth, photosynthesis and chlorophyll fluorescence of the seedlings. The results showed that D. trifoliata seedlings grew faster under 20‰ salinity. The root-shoot ratio declined with the increase of salinity, indicating salt stress had a greater effect on underground biomass than aboveground biomass. Net photosynthetic rate （Pn）, transpiration rate （Tr） and stomatal conductance （Gs） decreased significantly with the increase of salinity. Intercellular CO2 concentration （Ci） decreased first and then increased, with the minimum value occurring under 20‰ salinity; while transpiration rate （Tr） and stomatal limitation value （Ls） exhibited a reverse trend. PS II actual photochemical quantum yield decreased significantly, while non-photochemical quenching coefficient was opposite. The results suggested that higher salinity inhibited the growth, photosynthesis and chlorophyll fluorescence of D. trifoliata seedlings and that lower salinity （≤20‰） was propitious to the growth of D. trifoliata seedlings.