Stimulatory and inhibitory effects of needle litter and grass extracts on the growth of some ectomycorrhizal fungi

Aqueous extracts of Scots pine needles, shoots and roots of the grass Deschampsia flexuosa were investigated for their effects on the growth of isolates of ectomycorrhizal fungi. The growth rates of Laccaria proxima and Rhizopogon luteolus were negatively affected by the needle extracts. Only the high concentrations of the needle extracts had significant inhibitory effects on the growth rates of Paxillus involutus and Xerocomus badius. The growth rate of Laccaria bicolor was significantly enhanced by the needle extracts. Extracts of the shoots of D. flexuosa had inhibitory effects on the growth rates of L. proxima, P. involutus and R. luteolus and a significant enhancing effect on the growth rate of L. bicolor. The shoot extracts contained about 3–5 times more high molecular weight components, aliphatic acids and phenolics than the root extracts.