Effects of white light(WL)、blue light(BL)、red light(RL) and far red light(FRL) on callus growth,flavonoids biosynthesis and phenylalanine ammonialyase (PAL) activity in the culture of Saussurea medusa Maxim. on solid medium were examined. The results showed that the growth of callus cells was significantly promoted by continuous RL, and moderately by WL and FRL, BL had nearly no effect on the cell growth, compared with that in darkness (Fig.2). However, BL had stronger promotion on PAL activity and flavono...