不同烤烟品种苗期质膜渗透性和光合作用对低温的响应

通过对低温（11℃和15℃）下NC82、新品系、云烟85和K326这4个品种烤烟苗期生理生化指标的测定,结果表明,（1）烟草幼苗经11℃、15℃持续低温处理,其质膜相对透性和丙二醛含量的应答反应强烈,都表现出大幅升高。15℃胁迫4d后丙二醛含量有所下降,表现出较强的自我调节能力;11℃在胁迫后7d后,烟苗相对电导率均高于50%,处于半致死状态。（2）15℃低温胁迫7d后,叶绿素含量、最大光化学效率略有回升,PSII反应中心逐渐恢复。低温下光合能力恢复要稍晚于质膜的自我修复,仍可作为抗寒性指标评价烟苗物质和能量的状况。

Response of Plasmolemma Permeability and Photosynthesis in Different Varieties of Flue-cured Tobacco Seedlings to Low Temperature

This paper based on physiological and biochemical indices of four leaves period flue-cured tobacco seedlings in low temperature（11℃ and 15℃）weredetermined,in order todiscuss its low temperature tolerance mechanism,find the physiological and biochemical indices ofdiagnosis its low temperature resistance ability.The results showed that：（1） Plasmolemma permeability and the malondialdahyde（MDA） content of tobacco seedlings responsed intensely in 11℃ and 15℃ environment,both of them greatly rised.The plasmolemma permeability and content of MDAdeclined 4days after stressed in 15℃,suggesting strong self-adjustment ability;7days after stressed in 11℃,its relative conductivity（RC） in leaves washigher than 50%,risked of semilethal menace.（2） Low temperature stressdropped net photosynthetic rate（Pn） in tobacco seedlings,the same status as intercellular CO2 concentration,chlorophyll content（chl） and maximal photochemical efficiency（Fv/Fm）,and presented a positive correlation,but theirdiversities in correlateion coefficients explained thedifferent inhibited photosynthesis mechanism in low temperature environment fromdifferent varieties of tobacco seedlings.7days after stressed in 15℃,the content of chl and Fv/Fm rebounded slightly,the reaction PS II recover gradually.Compare with plasmolemma self-repairing,the recovery of photosynthesis was later,but still could be considered as a low temperature resistance index to evaluate the condition of substance and energy in tobacco seedlings.