不同氮素水平对铁皮石斛UV-B辐射缓解作用研究

研究了高、中、低3种氮素营养水平(2.208 4,0.552 1和0.138 0g/L)对UV-B辐射(5.1,15.6μW/cm~2)下铁皮石斛的光合色素、类黄酮质量分数、苯丙氨酸解氨酶(PAL酶)活性及主要药用成分总多糖质量分数的动态变化情况,探讨了缓解铁皮石斛UV-B辐射伤害的适宜氮素营养条件.结果表明:低氮素营养条件下,铁皮石斛光合色素质量分数较低,但PAL酶活性强、类黄酮及多糖质量分数明显高,其类黄酮质量分数变化与PAL酶活性变化存在明显的正相关性.分析表明,低氮素营养条件虽然不利于铁皮石斛光合色素的形成,但促进类黄酮及药用成分多糖的积累,有助于缓解UV-B辐射带来的损伤.

Alleviation Effect of Nitrogen Concentration on Damage Effect of Dendrobium Officinale Kimura et Migo under UV-B Radiation

To explore the optimal nitrogen concentration of alleviation effect on the UV-B radiation damage of Dendrobium officinale Kimura et Migo (D.officinale) , the contents of photosynthetic pigments, flavonoids and polysaccharides and the activities of phenylalanine ammonia-lyase (PAL) have been investigated.The seedlings of D.officinale have been incubated at different nitrogen concentration (2.208 4 g/L, 0.552 1 g/L and 0.138 0 g/L) and then treated with UV-B radiation immediately at the dose of 5.1 W·cm-2 and 15.6 W·cm-2 respectively.The results show that the contents of photosynthetic pigments are decreased but the contents of flavonoids and polysaccharides and the activities of PAL enzyme of D.officinaleincreased in low nitrogen concentration under the same UV-B radiation.Besides, there is a significantly positive correlation between the changes of PAL activity and the content of flavonoids.It is suggested that low nitrogen concentration had an adverse effect on the synthesis of photosynthetic pigments, however, apositive effect on the accumulation of flavonoids and polysaccharides under UV-B radiation, which might ameliorate the damage of UV-B radiation of D.officinale.