外源2,4-表油菜素内酯对镉胁迫下黄瓜幼苗生长及光合生理特性的影响

Effects of exogenous 2,4-epibrassinolide on growth and photosynthetic physiological characteristics of cucumber seedlings under cadmium stress

为探究外源植物激素对重金属胁迫下植物生长和生理特性的作用,采用水培试验,研究叶面喷施2,4-表油菜素内酯(EBL)对镉胁迫下黄瓜幼苗生长及光合生理特性的影响。结果表明,100μmol·L^(-1)镉胁迫降低抗氧化酶活性,叶片SOD和CAT活性与对照组相比分别降低28.80%和19.57%,加剧膜脂过氧化程度,破坏黄瓜类囊体膜结构,抑制光合作用,降低生物量增加和镉积累。叶面喷施0.5μmol·L^(-1)EBL可提高镉胁迫下叶片SOD、POD和CAT活性,其中SOD和CAT活性与镉处理相比分别升高11.70%和11.90%,降低MDA含量,保持叶片细胞完整性,保护PSII反应中心,提高光合色素含量和净光合速率从而提高光合性能,增加生物量,减少黄瓜地上部和根部镉累积,促进镉胁迫下黄瓜幼苗生长。综上,EBL通过提高叶片抗氧化能力、改善光合性能,减轻镉对黄瓜幼苗的毒害。

To explore the effects of exogenous plant hormones on plant growth and physiological characteristics under heavy metal stress,hydroponic test method was used to study the effects of 2,4-epibrassinolide(EBL)on the growth and photosynthetic physiological characteristics of cucumber seedlings under cadmium stress.The results showed that 100μmol·L^(-1) cadmium stress reduced the activities of antioxidant enzymes,and the activities of SOD and CAT in leaves were reduced by 28.80%and 19.57%,respectively,compared with the control,which aggravated the degree of membrane lipid peroxidation,destroyed the structure of thylakoid membrane of cucumber,inhibited photosynthesis,and reduced biomass to increase cadmium accumulation.Spraying 0.5μmol·L^(-1) EBL on leaves could improve the activities of SOD,POD and CAT under cadmium stress.Compared with cadmium treatment,the activities of SOD and CAT in leaves were increased by 11.70%and 11.90%,respectively.The MDA content of cucumber was reduced,the integrity of leaf cells was maintained,the PSII reaction centers were protected,and the photosynthetic pigment content and net photosynthetic rate were increased to improve the photosynthetic performance,increase biomass,and reduce the cadmium accumulation in the aboveground and root of cucumber seedlings to promote the growth of cucumber seedlings under cadmium stress.In summary,EBL reduced Cd toxicity to cucumber seedlings by improving antioxidant capacity and leaf photosynthetic performance.