UV-B辐射对烟草(Nicotiana tobacum)叶片总多酚含量和PPO活性的影响

采用盆栽试验,以烤烟品种K326为供试材料,选择空间范围不大的云南玉溪大营街和通海2个不同海拔高度的植烟区为试验点,并选择玉溪烟区种植烤烟海拔最高的通海县(1806.0米),作为同一种植地分别减弱0%、25%、50%和65%UV-B辐射强度条件的控制试验区,探讨了烤烟生长过程中PPO活性和总多酚含量与UV-B辐射强度的时空动态变化之间的关系。结果表明:由于受两地不同降雨日数及云层覆盖的影响,UV-B辐射强度并不随海拔高度的升高而升高;PPO活性对UV-B辐射强度变化非常敏感,过高或过低的UV-B辐射强度将降低PPO活性,其中过高的UV-B辐射强度影响更大;在一定的UV-B辐射强度范围内,降低强度可提高PPO活性;与PPO活性相反,高的UV-B辐射强度可提高烟叶总多酚含量,但在一定辐射强度范围内,对其变化趋势影响不大;过低的UV-B辐射强度不仅降低总多酚含量,而且影响整个生长过程中总多酚含量的变化。

Effects of UV-B radiation on total polyphenol content and PPO activity in flue-cured tobacco leaves

Tobacco variety K326 was potted in two different altitude districts Da Yingjie and Tong Hai in a small range of Yuxi City, and under 0%, 25%, 50%, and 65% reduced UV-B radiation conditions in Tong Hai, which is the highest region in Yuxi tobacco region as a control experiment. The changes of PPO (polyphenol oxidase) activity and total polyphenol content with change of UV-B radiation in the process of tobacco leaf development were studied. Results showed that, UV-B radiation was not enhanced with increase of altitude due to difference in rainfall days and coverage of cloud in these two regions. PPO activity was sensitive to UV-B radiation, it decreased rapidly when the UV-B radiation intensity was higher or lower than a particular range of value, but it was more sensitive to higher UV-B radiation. In a range of UV-B intensity, the tendency of PPO activity was not influenced by reduced UV-B. Contrast to PPO activity, higher UV-B increased content of total polyphenol, but the trends were not influenced in a particular range of UV-B intensity. Low UV-B intensity reduced content of polyphenol.