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

Key words: 
• Dendrobium of ficinale kimura et migo /
• enhanced UV-B radiation /
• nitrogen /
• photosynthetic pigment

Abstract: 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.