Effect of Spraying Exogenous EBR and H₂O₂ on the Resistance of Tobacco Seedlings to Low Temperature Stress

PurposeTo study the protective effects of exogenous epibrassinolide (EBR) and hydrogen peroxide (H₂O₂) sprayed before low temperature stress on the physiology and growth of tobacco seedlings.

MethodsThe test materials were tobacco varieties K326 and Xiangyan No.7. Foliar sprays of 0.01 mg/L EBR and 340 mg/L H₂O₂ were applied at the seven-leaf-one-center stage, and then treated with low temperature stress for four days. The antioxidant enzyme activities, osmoregulatory substances contents, malondialdehyde (MDA) content, and biomass of tobacco leaf seedlings were measured.

Results1) After low temperature stress, the leaf area, biomass and root-shoot ratio of two varieties of tobacco decreased, but MDA content increased. The antioxidant enzyme activities and osmoregulatory substance contents of K326 were reduced; while only POD and CAT activities and soluble protein content were reduced in Xiangyan No.7. 2) Compared with the only low temperature stress treatment, biomass, antioxidant enzyme activities and osmoregulatory substance contents of K326 were significantly higher (P<0.05) and MDA content was significantly lower (P<0.05) in the sprayed exogenous substance+low temperature treatment. 3) Compared with the only low temperature stress treatment, the change of MDA content of Xiangyan No.7 was not significant (P>0.05), and only some osmoregulatory substances contents and antioxidant enzyme activities were higher in the sprayed exogenous substance+low temperature treatment, but the overall changes were smaller than that of K326.

ConclusionExogenous EBR and H₂O₂ were applied as protectants to improve the tolerance of both tobacco varieties to low temperature stress, and the protection effect was better for K326.