Comparative water relations of container-grown and bare-root ectomycorrhizal and nonmycorrhizal Quercus velutina seedlings

A 2 × 2 factorial field experiment was conducted with black oak (Quercus velutina) to examine the effects of seedling production method (container-grown vs. bare-rooted) and inoculation with Pisolithus tinctorius on seedling water relations and soil–plant liquid flow resistance (Rs-P). Over the study period, bare-rooted and noninoculated seedlings exhibited midday values of leaf water potential (Ψ) which were lower than container-grown and Pisolithus-inoculated seedlings. During a mild drought in July similar trends were seen in predawn Ψ. Flow resistance between bulk soil and leaf was lower in container-grown and Pisolithus-inoculated plants than in bare-rooted and noninoculated plants; Rs–p was particularly high in bare-rooted plants which were not inoculated with Pisolithus. The exact mechanism(s) accounting for the differences in Rs–p of mycorrhizal vs. nonmycorrhizal plants could not be ascertained by the techniques employed. Low Rs–p in container-grown plants was associated with greater total root system length.