Growth profile of ectomycorrhizal fungal mycelium: emphasis on substrate pH influence

A knowledge of behaviour of ectomycorrhizal fungal isolates to substrate pH would help in identifying candidate fungi for plantation programs. Ectomycorrhizal fungus isolates were studied to determine the pH optima for growth, substrate acidification by the culture and the effect of substrate acidification on culture growth. Of the isolates tested, the members of Agaricales (except Laccaria laccata) and Aphyllophorales favored neutral to near neutral pH, while members of the order Sclerodermatales strictly favored acidic pH. The change in substrate pH (DeltapH) was maximum at the optimum growth pH for acidophilic isolates but minimum for neutro/basophilic isolates. The experiments indicate that the substrate pH would not only determine the growth rate of the fungus but also limits further proliferation of the fungus in medium. This gives vital information for determining the subculture frequency and for designing substrate parameters for nursery/plantation programs.