镉胁迫下硒对罗汉果组培苗光合特性的影响

实验以罗汉果组培苗为材料,室内栽培在内装市售营养土的塑料盆中,以0、10、50、100、200mg·kg-1浓度镉离子和1mg·kg-1浓度硒处理,培养20d后分析罗汉果幼苗的相关光合生理指标。结果表明:低浓度Cd2+对叶片叶绿素含量、光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)影响不大或稍有上升,但高浓度镉离子处理植株叶片的叶绿素含量、光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)明显下降;随Cd2+处理浓度的增加,叶片胞间CO2浓度(Ci)呈现上升趋势;加硒则延缓叶绿素下降,促进光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)上升,降低叶片胞间CO2浓度(Ci)。表明高浓度镉离子的毒害导致罗汉果组培苗叶片光合性能受到伤害,从而影响罗汉果幼苗生长。镉硒混合处理反映出硒对镉的毒害有缓解作用。

Effects of Se on photosynthetic characteristics of Siraitia grosvenorii seedling under Cd2+ stress

The tissues cultured seedlings of Siraitia grosvenorii were used as the material which were planted in the indoor cultivation and the soil with nutrition bought from market. The cultured seedlings of S. grosvenorii were added different concentrations of Cd²⁺(0,10,50,100,200 mg·kg^-1 )and Se²⁺(1 mg·kg^-1)into mediums under sterile conditions. The correlative photosynthetic characteristics indices were analyzed after cultivating 20 d. The results showed that the low concentration Cd²⁺had the effect on the contents of chlorophyll,photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)were not big or increased slightly. But under high concentrations treatment of Cd²⁺,the contents of chlorophyll,photosynthetic Rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of leaves decreased obviously. With the increase of Cd²⁺ concentration,the rising trend appeared in leaf intercellular CO₂ concentration,the addition of Se delayed the decline of chlorophyll,and made photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs)increased,but reduced the leaf intercellular CO₂ concentration(Ci). It was shown that the toxicity of high concentrations of cadmium ions could also hurt photosynthetic characteristics of S. grosvenorii seedling,which,therefore,affected the growth of S. grosvenorii seedling. The mixed treatment of cadmium and selenium reflected that selenium had alleviated function on the toxicity of cadmium.