Root hydraulic conductivity of vesicular–arbuscular mycorrhizal green ash seedlings

SUMMARY Green ash (Fraxinus pennsylvanica Marsh.) was either inoculated or not with Glomus etunicatum Becker and Gerd. and grown for 37 d to permit root colonization. Root hydraulic conductivity (Lpp) per unit length was measured on excised root systems to examine the influence of vesicular arbuscular (VA) mycorrhiza inoculation, seedling size, phosphorus (P) nutrition, and biomass distribution. Fertilization with P eliminated significant differences in seedling size and dry matter distribution between mycorrhizal (M) and non‐mycorrhizal (NM) seedlings, but VA mycorrhizas increased root and leaf P concentration. Root Lp was similar in M and NM seedlings of similar size, and was lower in M seedlings for a given root P concentration. Root Lp decreased with age and weight, and increased as the proportion of dry weight in the leaves increased in both M and NM seedlings. Mycorrhizal colonization had no significant effect on root Lp in the absence of a significant growth response.