关键词: 烤烟, 重金属, 复合作用, 抗氧化酶, 碳氮代谢

Abstract: In order to explore the effects of Pb and Zn combination  on tobacco antioxidant enzymes and carbon-nitrogen metabolism, this paper used flue-cured tobacco Honghuadajinyuan as tested variety, and investigated the effects of different concentration Pb (0, 150, 450, 750 mg·kg^-1) and Zn (0, 20, 60, 100 mg·kg^-1) on the activity of superoxide dismutase(SOD), peroxidase(POD), nitrate reductase (NR) and sucrase, and contents of malondialdehyde (MDA), proline, protein and soluble sugar of tobacco leaf by two-factor factorial experiment under soil culture. The results showed that: single Pb and Zn displayed low concentration promotion and high concentration inhibition on tobacco antioxidant enzyme activity and carbon-nitrogen metabolism. Zn and Pb were the main influencing factors of tobacco leaf sucrose enzyme and POD activity, respectively. The interaction of Pb×Zn showed significant effects on the antioxidant system and carbon-nitrogen metabolism of tobacco. The low or middle concentration of Pb and Zn interaction produced the antagonistic effect on tobacco, activated the antioxidant enzymes and promoted the carbon and nitrogen metabolism. Moreover, when one metal element concentration was higher and the other was lower, Pb and Zn combination also had  synergistic effect, which inhibited the antioxidant enzymes activity and carbon-nitrogen metabolism, and aggravated heavy metals toxicity to tobacco.

Key words: flue-cured tobacco, heavy metal, combination effect, antioxidant enzymes, carbon and nitrogen metabolism