摘要： 为明确Cd胁迫对烤烟叶片光合作用的影响，在水培条件下，研究了Cd胁迫对烤烟叶片叶绿素含量、光合气体交换特性、叶绿素荧光参数的影响。结果表明，Cd胁迫导致了烤烟叶片叶绿素含量的降低，特别是叶绿素a较叶绿素b对Cd胁迫更为敏感。在低于75 μmol/L Cd胁迫下烤烟叶片净光合速率（Pn）的降低主要与气孔导度的降低有关，但当Cd浓度增加到100 μmol/L时，烤烟叶片光合能力的降低为气孔和非气孔因素共同限制的结果。低于50 μmol/L的Cd胁迫下，烤烟叶片的非化学淬灭（NPQ）和依赖于类囊体膜两侧质子梯度和叶黄素循环的量子产额（Y_NPQ）随着Cd浓度的增加而增加，即此时烤烟叶片主要通过增加依赖于叶黄素循环的非辐射能量耗散机制来降低烤烟叶片中过剩光激发能，但随着Cd浓度的进一步增加，烤烟叶片过剩光能（1-q_P）/NPQ和失活PSⅡ反应中心的热耗散量子产额（Y_NF）大幅增加，PSⅡ反应中心的光抑制程度增加，但在此时，热耗散和反应中心的失活为烤烟叶片抵御Cd毒害主要的光破坏防御机制。此研究可以为烤烟的耐Cd机理提供一定的基础数据。

关键词: 烤烟, 镉, 光合特性, 叶绿素荧光

Abstract: In order to measure the effect and action mechanism of cadmium(Cd) on the photosynthetic characteristics in the leaves of flue-cured tobacco,flue-cured tobacco was cultured in a solution containing different concentrations of Cd. The effects of Cd stress on the chlorophyll content,photosynthetic gas exchange and chlorophyll fluorescence parameters in the flue-cured tobacco leaves were investigated. The results showed that the chlorophyll content in the flue-cured tobacco leaves declined as the Cd concentration increased. The chlorophyll a content,in particular,was reduced to a much greater extent than chlorophyll b content. The photosynthetic capacity in the leaves of flue-cured tobacco was reduced mainly associated with the stomatal conductance until the Cd concentration reached 75 μmol/L. But,when Cd concentration reached 100 mol/L,the cause of flue-cured tobacco leaf photosynthetic capacity decreased to were the stomatal and non stomatal factors common restrictions. The non-photochemical queching(NPQ) and the quantum yield of light-dependent and ΔpH-and xanthophyll-mediated regulated thermal dissipation(Y_NPQ) was increased below the 50 μmol/L Cd,that means the flue-cured tobacco leaf was mainly by increasing non-radiative energy dissipation mechanisms by xanthophyll cycle to reduce the flue cured tobacco in excess excitation energy,but with the further increase of Cd concentration,NPQ and Y_NPQ was reduced,which leads to the excess light energy(1-q_P)/NPQ,the quantum yield or flux of thermal dissipation in non-functional PSⅡ and the degree of photoinhibition of PSⅡ reaction center increased dramatically,at this point,the heat dissipation and the reaction center inactivation was the major photoprotective mechanisms in leaves of flue-cured tobacco to defense the Cd poisoning. This study would provide some basic data for seeking Cd-resistant mechanism of tobacco.

Key words: Flue-cured tobacco, Cadmium, Photosynthetic characteristics, Chlorophyll fluorescence

中图分类号: 

• Q945.1

• S572.01