Mycorrhizal and non-mycorrhizal Douglas fir grown in hydroculture. The effect of nutrient concentration on the formation and functioning of mycorrhiza

A series of experiments using the Douglas fir as the subject of research were performed in hydroculture. Different relative nutrient addition rates were used prior to and after plants had been inoculated with Laccaria bicolor. The effect of the resulting nutrient conditions on mycorrhiza formation was studied together with the effects on growth and internal nutrient levels. The level of external nutrient concentration influenced mycorrhiza formation and functioning. In general, very low and limiting external nutrient conditions resulted in rapid and good mycorrhiza formation, with the mycorrhiza plants having the same or a lower fresh weight than those of the non-mycorrhizal plants. While under higher nutrient conditions mycorrhiza formation was slower and less abundant, and the mycorrhizal plants had a larger total fresh weight than nonmycorrhizal plants.