Early developmental responses of mountain birch (Betula pubescens subsp. czerepanovii) seedlings to different concentrations of phosphorus.

Phenolic compounds, identified by high performance liquid chromatography (HPLC), and growth were investigated in the first true leaves, cotyledons, stems and roots of 2.5-week-old seedlings of mountain birch (Betula pubescens subsp. czerepanovii (Orlova) Hämetahti) grown with 1.5, 15 and 50 ppm phosphorus (P). Phenolic compounds in seeds and unfertilized 6-day-old seedlings were also studied. Seeds contained few phenolics, but had an abundance of condensed tannins. There were fewer HPLC phenolic compounds in 6-day-old seedlings than in 2.5-week-old seedlings. In 2.5-week-old seedlings, growth of the first true leaves, but not of other plant parts, was affected by P regime. In the first true leaves and stems, the concentration of condensed tannins was significantly affected by P, being higher at 1.5 ppm than at higher concentrations. The concentration of total HPLC phenolics was significantly affected by P only in stems.