Influence of daub exogenous ascorbic acid and glutathione on wounds after tobacco topping on redox equilibrium and nicotine content of tobacco

Nicotine is not only an important chemical component of tobacco leaves, but also one of the important quality indexes of cigarette. The current state of flue-cured tobacco in China with nicotine on the high end has severely influenced China-produced tobacco leaf quality. Effectively reducing nicotine content of tobacco leaves and improving flue-cured tobacco usability has been a difficult issue in the tobacco production industry. The content of nicotine in tobacco doubled and redoubled after topping. Because of the sharp rise in nicotine content after tobacco topping and cells oxidative burst due to mechanical damage, testing started with a series of physiological changes induced by?topping in this study. The two methods used in the test included daub of both ascorbic acid and glutathione (AsA+GSH), and daub of ascorbic acid (AsA). Other three methods were also applied in the experiment, duab of buffer solvent after topping, conventional topping and not topping. These methods were applied to tobacco wounds after topping to suppress the rise in active oxygen content, explore the relationship between active oxygen content and jasmonic acid-stimulating nicotine content growth, and to compare the effects of the two methods on suppressing the rise in active oxygen and nicotine content. The results showed that the rise in the contents of super oxygen anion, hydrogen peroxide and malondialdehyde of tobacco leaves dropped when daubing AsA+GSH and AsA to the topping wounds. Hydrogen peroxide degradation was slower than that of oxygen anion, which accumulated in tobacco. Jasmonic acid content under daub of AsA+GSH or AsA treatments was lower than that under conventional topping treatment at 6 h after treatment and with adverse effect on jasmonic acid. At 96 h after treatment, nicotine content of leaves under AsA+GSH treatment was 21.5% lower than that under conventional topping treatment. The content of nicotine in tobacco leaves under AsA treatment was 17.5% lower than that under conventional topping treatment. Correlation analysis among response intensity of each detection index to topping showed significant or extremely significant correlation between the detection indexes. Also at 24 h after topping, active oxygen content of each treatment dropped back to the non-topped level (not topping treatment). The test showed that daubing antioxidant substances (AsA+GSH) to tobacco wounds after topping effectively suppressed reactive oxygen species, jasmonic acid and nicotine contents rise. There was also a close relationship between reactive oxygen species, jasmonic acid and nicotine. AsA+GSH treatment was better than AsA treatment in antioxidant activity, and was therefore better in suppressing nicotine content rise in tobacco leaves after topping.