Discussion On Effects Of Enhanced Uv-b Radiation Of Quality Of Flue-cured Tobacco

Enhanced UV-B radiation may directly or indirectly cause changes of morphology, physiology, genetic trait and the growth cycle, etc of plants. Field test was conducted systematically for two consecutive years to study the effect of enhanced ultraviolet B radiation on primary metabolism and chemical material accumulation of flue-cured tobacco in field production and natural light conditions. The main results were as follows:1. he changes of three antioxidant enzyme systems activity (peroxydase, catalase, superoxide dismutase) under two kinds of UV-B radiation strength stress in two main grown flue-cured tobacco in Yunnan province(HD and Yunyan87) was studied. The result showed that low strength of UV-B radiation inhibited the activity of catalase and superoxide dismutase, and high strength of UV-B radiation inhibited the activity of catalase and superoxide dismutase in the leaves of HD; the activity of catalase and superoxide dismutase increased with the strength of UV-B radiation enhancing in the leaves of Yunyan 87. As the increase of UV-B radiation strength, the activity of peroxydase in HD went to higher and declined in Yunyan 87.2. UV-B radiation have different effect on the growth of HD and Yunyan87. Soluble sugar content of these two varieties was negatively correlated with radiation intensity; the increasing rate of total nitrogen and nicotine of Yunyan87 is positive related with UV radiation intensity; the chemical component change of HD is not regular.3. The flavonoid content of HD and Yunyan87 was positively correlated with the intensity of UV-B treatment. Phenolic content of Yunyan87 was increased with the intensity of UV radiation and then decreased.4. Chlorophyll content of HD was increased with the intensity of UV radiation and then decreased. Chloroplast pigments of Yunyan87 were positively correlated with UV radiation intensity.