重金属递进胁迫对黑麦草初期生长的影响

通过研究Cu²⁺、Zn²⁺、Cd²⁺与Pb²⁺胁迫对黑麦草初期生长的影响，结果表明：4种重金属对种子发芽率抑制效应相对较小，尤其Cu²⁺与Zn²⁺的抑制作用最小。高浓度Cu²⁺、Cd²⁺胁迫对株高、根系长度、地上生物量的抑制作用相对较大，尤其Cu²⁺对根系生长的抑制效应最大，在300 mg·L^-1下，与对照相比，根长最高下降了 85.48%。高浓度Cd²⁺胁迫显著降低了叶绿素含量，在300 mg·L^-1时比对照降低了45.51%；与对照相比，Cu²⁺与Zn²⁺所有处理都增加了叶绿素含量。从递进胁迫进程看，一些重金属对某一生长指标的影响往往表现在低浓度具有促进作用，而高浓度又存在明显的抑制效应。

Effects on initial growth of Lolium perenne under heavy metal progressive stress

The experiment was conducted to investigate effects on initial growth of Lolium perenne L.under Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ stress. The results showed that four heavy metals didn’t inhibit seed germination significantly, especially Cu²⁺ and Zn²⁺ stress. At high concentrations, Cu²⁺ and Cd²⁺ stress decreased plant height, root length and aboveground biomass greatly, especially Cu²⁺ which inhibited root growth mostly. Compared with control, root length decreased by 85.48% at Cu²⁺ level of 300 mg·L^-1. High level of Cd²⁺ decreased chlorophyll content significantly. Compared with control, chlorophyll content decreased by 45.51% at Cd²⁺ level of 300 mg·L^-1. Chlorophyll contents increased at all stress levels of Cu²⁺ and Zn²⁺.From the process of progreessive stress, some heavy metal had positive effect on some growth index at low concentrations, but inhibited growth at high concentrations.