Study on Relationship between Nitric Oxide and Nitrate Reduction in Leaf of Alnus cremastogyne

The nitric oxide(NO)content and nitric oxide synthase(NOS)activity in seedlings varied with the growing period of Alnus cremastogyne. In the initial stage,NO content and NOS activity were low. They gradually raised until the peak of the growth. When leaf began aged,the NO content and NOS activity turned to low level. The changes of nitrate reductase(NR)and glutamine synthase(GS)activities in growing period were similar to the NOS,but the maximum activity of NR appeared earlier than that of NOS. The former was in June and the latter was in July. GS maximum activity appeared in September. When leavies were directly exposed to NO(5～30 μmol·L-1),NO content and NOS activity appeared obvious increase. NR activity in seedling leaf(in vivo)raised,and in young tree leaf(in vitro)reduced. Treated with NO the nitrate reductase(NR)activity in branch’s leaf cultivated in KNO3 solution(0.05 mol·L-1)obviously raised. If branch were directly cultivated in KNO3 solution,NO content and NOS activity appeared increase except for NR activity. The results showed that there exist relationship between the level of NO and NOS,and growing of A. cremastogyne. NO related to nitrate reduction.