Abstract: Nitrate reductase (NR) activity and the content of nitrogen nutrition and amino acid(AA)were measured in different season, and their relationship with growth was analyzed. The results showed that most of the nitrogen nutrition of conifer of L. olgensis was NH₄-N, the content of NO₃-N and NO₂-N was very low. The content of NH₄-N and T-N(NO₃-N+NO₂-N+NH₄-N)correlated with NR activity positively in L. olgensis of different provenances. At the beginning of growth season, the content of nitrogen nutrition of conifer was lower in L. olgensis, and correlated with gorth positively;while those at the middle and end of growth season were higher, but had no relationship with growth. The seasonal variation of AA content was similar with that of nitrogen nutrition in L. olgensis, but had no relationship with growth. At the beginning of growth season, NR activity of conifer correaed with growth positively in L. olgensis of different provenances. Preliminary results indicated that at the beginning of growth season NR activity, content of NH₄-N and T-N maybe become physiological and biochemical indices of early provenance selection in L. olgensis.

Key words: Larix olgensis Henry, Nitrate reductase, Nitrogen nutrition, Amino acid, Early provenance selection