At all salinity levels, total free amino acids and proline concentrations were lower in mycorrhizal than in non-mycorrhizal plants, although the difference in total free amino acid concentration was not significant in the 0 g kg −1 NaCl treatment. Concentrations of total free amino acids and proline increased with increasing salinity in nonmycorrhizal plants, but not in mycorrhizal plants (Fig. 2c, d).