铬胁迫对油桐幼苗生理特性及叶片结构的影响

Effects of different concentrations of chromium on the photosynthetic characteristics and leaf structure of tung tree(Vernicia fordii)seedlings

【目的】研究油桐对土壤铬胁迫的响应机制,为油桐修复铬污染的土壤环境提供技术支撑。【方法】以1年生油桐盆栽苗为试验材料,研究外施不同浓度铬含量(0、50、100、200和500 mg·kg^(-1))土壤对油桐幼苗光合作用、叶绿素含量、过氧化物酶(POD)、超氧化物歧化酶(SOD)、丙二醛(MDA)含量、相对电导率、气孔张开率和叶片结构的影响。【结果】1)与对照相比,在铬浓度为50 mg·kg^(-1)的土壤下,油桐幼苗生长无显著差异;2)在铬浓度为100 mg·kg^(-1)的土壤下,油桐叶片的净光合速率(Pn)、叶绿素含量、可溶性蛋白含量显著降低(P<0.05);3)铬浓度为200 mg·kg^(-1)的土壤下,油桐的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO_(2)浓度(Ci)显著降低(P<0.05),可溶性蛋白含量下降、MDA、SOD含量上升,气孔张开率降低,叶片厚度显著变薄(P<0.05);4)铬浓度为500 mg·kg^(-1)的土壤下,经过长期铬胁迫(60 d),油桐幼苗的光合系统受到严重破坏,Pn相比于对照降低了89.02%,总叶绿素Chl(a+b)含量降低了24.35%,MDA含量上升了47.18%,造成膜脂过氧化,相对电导率上升了1.43%,叶片厚度降低26.71%(P<0.05);5)油桐幼苗各部位金属铬含量随着土壤外施铬浓度的上升而增加,且金属铬在油桐幼苗根部的积累量最多,5个处理组的油桐幼苗根部铬积累量分别是叶片的61.51、22.30、61.77、64.18和38.25倍。【结论】油桐在土壤铬浓度不超过100 mg·kg^(-1)时可以吸收土壤中的铬,起到修复土壤重金属的效果。

【Objective】This study investigated the response mechanism of tung tree seedlings to chromium stress,in order to provide technical support for the application of tung trees in repairing soil environment polluted by chromium.【Method】A pot experiment was carried out by using the one-year-old tung tree seedlings as the materials,to study the application of different concentrations of Cr(0,50,100,200 and 500 mg·kg^(-1) soil)on the photosynthesis,chlorophyll(Chl)content,peroxidase(POD),superoxide dismutase(SOD),malondialdehyde(MDA)content,relative conductivity,stomatal width,leaf structure and chromium content of tung trees.【Result】1)The result indicated that when the soil Cr^(3+)concentration was 50 mg·kg^(-1),the growth of tung tree seedlings showed no significant difference in comparison with the control;2)With a soil Cr^(3+)concentration of 100 mg·kg^(-1),the net photosynthetic rate(Pn),chlorophyll(Chl)content,and soluble protein content of leaves were significantly reduced(P<0.05);3)When the soil Cr^(3+)concentration exceeded 200 mg·kg^(-1),the photosynthesis of tung tree seedlings was significantly decreased(P<0.05),the contents of MDA and SOD increased,and the stomatal width and the thickness of leaves was significantly reduced(P<0.05);4)After long-term chromium stress(60 d)of 500 mg·kg^(-1) Cr^(3+),the photosynthetic system of tung tree seedlings was severely damaged.Pn decreased by 89.02%compared with the control,and the total chlorophyll content decreased by 24.35%.The MDA content increased by 47.18%,resulting in membrane lipid peroxidation,the relative conductivity increased by 1.43%,and the blade thickness decreased by 26.71%(P<0.05);5)The content of Cr^(3+)in each part of the tung tree seedlings increased with the increase in the chromium concentration of soil.The accumulation of Cr in the roots of tung tree seedlings was the highest,and the accumulation of Cr in the roots of the tung tree seedlings in the 5 treatment groups were 61.51,22.30,61.77,64.18 and 38.25 times that of the leaves,respectively.【Conclusion】Taken together,tung tree seedlings can absorb chromium in soil when the chromium concentration does not exceed 100 mg·kg^(-1) in soil,playing a role in remediating heavy metal soil.