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为了解硫化氢（H₂S）对Cd²⁺ 胁迫下小麦幼苗生长的缓解机理，以小麦品种苏科麦一号为材料，在水培条件下，测定外源H₂S（供体为NaHS溶液）预处理对Cd²⁺ 胁迫下（CdCl₂浓度为50 μmol·L^-1 ）小麦幼苗生长和生理指标的影响。结果显示，外源H₂S预处理显著提高Cd²⁺ 胁迫下小麦幼苗的株高、地上部生物量、非蛋白巯基化合物含量、叶片光合色素含量、净光合速率、叶绿素荧光相关指标（PS Ⅱ的光合性能指数、单位激发态面积吸收的能量、用于还原Q_A和用于电子传递的能量、非光化学淬灭）和根部Cd含量；显著降低小麦叶片中的过氧化物质（丙二醛、过氧化氢和超氧根阴离子）含量及地上部分Cd含量和Cd转运系数。综上所述，外源H₂S预处理可清除Cd²⁺ 胁迫小麦幼苗叶片中的活性氧自由基，减少其对光合色素分子的破坏，降低膜脂过氧化程度，保护光合电子传递系统，增加热耗散，提高光合能力，缓解Cd²⁺ 对小麦幼苗生长的抑制，以50 μmol·L^-1 的NaHS效果最好。

英文摘要:

To explore the beneficial effect of hydrogen sulfide(H₂S) on the growth of wheat seedlings under Cd²⁺ stress,a wheat cultivar Sukemai 1 was used as the experimental material in this study.The effects of H₂S(different concentrations of NaHS were served as H₂S donor) on the growth and physiological changes of wheat seedlings under Cd²⁺ stress(CdCl₂ concentration of 50 μmol·L^-1 ) were studied through hydroponic method.The results showed that exogenous H₂S significantly improved the plant height,shoot biomass,non-protein thiol content,photosynthetic pigment contents,net photosynthetic rate,chlorophyll fluorescence parameters including photosynthetic performance index of PS II,the absorption of light energy,trapped energy fluxes for reducing Q_A,the electron transport in PS II cross-section and non-photochemical quenching of wheat leaves under Cd²⁺ stress.Cd concentration in roots were also increased.While the content of antioxidants,such as malonaldehyde,hydrogen peroxide and superoxide anion in wheat leaves,Cd concentration in shoots,and Cd transport factor were significantly reduced by pretreatment of H₂S on wheat seedlings under Cd²⁺ stress.In summary,the harmful effects of Cd²⁺ on wheat seedlings were mitigated by exogenous H₂S through scavenging reactive oxygen free radicals in the leaves to decrease the destruction of photosynthetic pigments,to reduce the damage from peroxidation of membrane lipid,to protect the photosynthetic electron transfer system,to increase the heat dissipation,as well as to improve the photosynthetic capacity,and to alleviate the growth inhibition caused by Cd²⁺ ,and the optimal NaHS concentration was 50 μmol·L^-1 .

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