Spore Populations and Infectivity of Vesicular Arbuscular Mycorrhizal Fungi in New South Wales

Abstract

Spores of vesicular arbuscular (VA) mycorrhizal fungi were found in all 73 soil samples collected from different parts of New South Wales. Their numbers ranged widely from site to site (from 2 to 1952 spores per 100 g dry soil) and varied considerably for the same crop at different sites (e.g. from 47 to 464 spores per 100 g dry soil for wheat). In general there were more spores in agricultural than in native grassland-bush soils. Of the eight species found, Acaulospora laevis and Glomus mosseae were the commonest. Small spores of the Glomus fasciculatus and G. microcarpus groups were also frequent but Gigaspora spp. were fairly rare. Usually more than two VA species occurred at each site. The infectivity of the VA population in soil, assayed by measuring the rate of mycorrhizal develop- ment in clover seedlings, did not correlate with spore numbers.