The effects of irradiance on the production of phenolic compounds and condensed tannins in Larix gmelinii needles

Needles of Larix gmelinii seedlings grown under different irradiances (100, 52, and 26 % of natural sunlight) were collected from June to August 2009. The content of phenolic compounds and condensed tannins in needles were strongly affected by different irradiances. The highest content of phenolic acids occurred under the lowest irradiance. Chlorogenic acid and syringic acid were detected only under the shade. In contrast, the needles under full irradiance showed the highest content of condensed tannins.