Cd胁迫下白桦光合及叶绿素含量的响应研究

Study on responses of photosynthesis and chlorophyll content of Betula Platyphylla Suk.under Cd stress

以2年生白桦幼苗为对象,采用盆栽试验,研究镉(Cd)胁迫对白桦光合荧光特性及叶绿素含量的影响.结果表明:Cd胁迫显著减少白桦叶片的叶绿素含量(P<0.05),阻碍电子传递,减弱光捕获能力和光能利用能力,从而抑制其光合作用.胁迫5周后,Cd暴露浓度为50 mg/kg时,与空白相比,白桦的净光合速率(Pn)增长了11.84%,表明低浓度Cd胁迫对白桦光合作用具有一定的促进作用;Cd暴露浓度为100 mg/kg时,与胁迫3周后相比,白桦的Pn增长了25%.Cd暴露浓度低于100 mg/kg时,白桦叶片的ΦPSII、NPQ和ETR等参数基本维持在一定的范围,说明白桦具有强的耐受性.

The effects of Cadmium(Cd)stress on photosynthetic fluorescence characteristics and chlorophyll content of 2-year-old Betula Platyphylla Suk.seedlings were studied in a pot experiment.The results showed that Cd stress significantly reduced the chlorophyll content of Betula Platyphylla Suk.leaves(P<0.05),hindered electron transport,and reduced light-capturing ability and light energy utilization ability,thereby inhibiting photosynthesis.After 5 weeks of stress,compared with the control,the net photosynthetic rate(Pn)of Betula Platyphylla Suk.increased by 11.84%when Cd was exposed to 50 mg/kg,indicating that low-concentration Cd stress promoted photosynthesis of Betula Platyphylla Suk.Similarly,compared to 3-weeks stress,the Pn of Betula Platyphylla Suk.increased by 25%after 5 weeks when the concentration of Cd was 100 mg/kg.When the Cd exposure concentration was lower than 100 mg/kg,the parameters ofΦPSII,NPQ and ETR of Betula Platyphylla Suk.leaves were basically maintained in a certain range,indicating that Betula platyphylla had strong tolerance.