EFFECT OF PHOSPHATE FERTILIZATION ON THE POPULATIONS OF ARBUSCULAR MYCORRHIZAL FUNGI

The tolerance of four populations of arbuscular mycorrhizal fungi to t he increased long-term phosphate fertilization was studied in hydropon ic experiment with four levels of phosphate and maize as a host. The l evels of mycorrhizal infection indicators (frequency of infection, int ensity of infection and arbuscule abundance in the infected root) decr eased with increased concentration of phosphate in nutrient solution. The intensity of infection was slightly lower in treatments inoculated with the soil overfertilized with phosphate for 10 years. The interac tion between field fertilization and concentration of phosphate in the nutrient solution as sources of variability was not found, indicating the equal tolerance of populations from phosphate fertilized and unfe rtilized soil to phosphorus. Parallel cultivation of fungal population s in soil under two nutritional regimes, using leek as a host, showed the significant influence of long term phosphate overfertilization to the species composition of populations.