关键词: 蒿柳, 硅, 铅, 膜脂过氧化, 调控

Abstract: [Objective] In order to ascertain the physiological mechanism of Si-alleviated Pb toxicity in the Salix viminalis and provide theoretical basis for the Si treatment in heavy metals contaminated soil, it was analyzed the effect of Si on Pb distribution and transport under Pb stress, membrane lipid peroxidation and osmoregulation response to Pb stress in the S. viminalis.[Method] With the disposal method of applying Si after Pb stress, Pb concentration was set two levels including 0, 1.8 mmol·L^-1; Si concentration was set three levels including 0, 1.5, 5.0 mmol·L^-1. It had four blocks and each block was set six treatments. A sand culture experiment was conducted to study the regulation and control effect of Si on growth, Pb distribution and transport, membrane lipid peroxidation and osmoregulation of S. viminalis under Pb stress.[Result] Pb stress could significantly decrease the relative height and ground diameter growth rate, increase the relative electrical conductivity, O₂^·-producing rate, MDA content, pro and sp contents of the S. viminalis leaf and root. Compared with Pb treatment, by using 1.5 mmol·L^-1 Si after Pb stress, Si reduced the relative electrical conductivity, leaf O₂^·-producing rate, MDA content and the pro content of the S. viminalis root, increased the relative height and ground diameter growth rate. Simultaneously, Si significantly reduced the content by 90.92% on the ground of the S. viminalis, which increased the Pb content by 63.93% in the root of it, and the total Pb content by 43.36% in the S. viminalis. Using 5.0 mmol·L^-1 Si after Pb stress, it had no significant influence to relieve Pb stress. On the one hand, Si concentration might be too high; on the other hand, it might be that the adsorption of mineral elements and buffering capacity in sand are less than in soil.[Conclusion] By analyzing several aspects of growth index, membrane lipid peroxidation and the Pb distribution and transport for Si regulation under Pb stress in the S. viminalis, it showed that Pb inhibited the growth and caused membrane lipid peroxidation of the S. viminalis. Si alleviated Pb toxicity by reducing membrane lipid peroxidation and decreasing Pb transfer from the root to the shoot of the S. viminalis. Besides, that Si improved the total Pb in the S. viminalis and inhibited Pb release to the outside. These characteristics provided theoretical basis for the Si treatment in heavy metals contaminated soil. This study is a sand culture experiment, the adsorption and diffusion barrier effects in gravel are different from that in soil. So, Si concentration, whose reaction in different plants and soil conditions is different. Therefore, it needs further research and practice in the Si treatment of heavy metal contaminated soil.

Key words: Salix viminalis, silicon, lead, membrane lipid peroxidation, regulation