Abstract: In this paper,the changes of reactive oxygen species and chlorophyll fluorescence parameters in leaves of flue-curing tobacco seedlings in different combinations of simulating low temperature (8±2)℃ and light intensity(weak light:200 μmol/(m²·s),strong light:1 000 μmol/(m²·s)) in the early spring of northern China after chilling stress were studied,the aim was to exploit response mechanism of regular low temperature and strong light on survival and growth of transplanting tobacco seedlings.The results showed that after low temperature for 1,2 h,the rates of production of O₂^· had not changed significantly in the weak light treatment,while,the rates of production of O₂^· had increased significantly in the treatment of strong light.Meanwhile the produce rate of O₂^· and increasing contents of H₂O₂ in strong light were obviously higher than in weak light.The activity of SOD and APX were increased significantly in weak light after low temperature for 1,2 h and in strong light after low temperature for 1 h,while,the activity of SOD and APX were decreased mostly in the strong light after low temperature for 2 h.The changes of reactivity oxygen species in tobacco leaves under different stress resulted in the numerous MDA accumulation,the extent of membranous peroxide had been increased.Samely,the MDA contents in strong light treatment were more than in weak light treatment,and the MDA contents in low temperature for 2 h were more than for 1 h.The parameters of Fv/Fm and Fv/Fo were not changed significantly in weak light after low temperature for 1,2 h,while,parameters of Fv/Fm and Fv/Fo were decreased mostly in the strong light after low temperature,and degree of decreasing in low temperature for 2 h were more than for 1 h.

Key words: Low temperature, Light intensities, Flue-curing tobacco, Reactive oxygen species, Chlorophyll fluorescence

CLC Number: 

• S572.01

• Q945.1