Influence of salinity on biomass production by Australian Pisolithus spp. isolates

Eighteen isolates, comprising three putative Pisolithus species from easter n and central Australia, were screened for resistance to NaCl during growth in axenic culture. Biomass yield for most isolates showed a decline with i ncreasing NaCl up to 200 mM; however, only five isolates reached an EC50 po int (effective concentration inhibiting growth by 50%) below 200 mM NaCl. M ost Pisolithus isolates were thus found to be resistant to NaCl at concentr ations found in very saline soils. Of five isolates screened for Na2SO4 res istance, none reached an EC50 point below 100 mM. While intraspecific varia tion was evident in the resistance of isolates to both salts, no obvious pa tterns of interspecific variation were observed. The data thus indicate tha t isolates of the three Australian Pisolithus species are broadly resistant to salinity and may represent useful ectomycorrhizal inoculants for outpla nting of compatible, salt-resistant host trees at saline sites.