Ectomycorrhizae and Drought Acclimation Influence Water Relations and Growth of Loblolly Pine

Abstract

The influence of ectomycorrhizae on drought acclimation was studied in an open-pollinated family of loblolly pine (Pinus taeda L.). Seedlings inoculated with Pisolithus tinctorius (Pers.) Coker and Couch (Pt) maintained a higher shoot relative growth rate under high and low soil moisture regimes. However, fascicle area, shoot and root mass, and fascicle nutrient elemental content were similar for seedlings inoculated with Pt and noninoculated seedlings. Seedlings under low soil moisture were drought-acclimated by five 11-day drought cycles. During peak water deficit (cycle 6), drought-acclimated, Pt-inoculated seedlings had the lowest predawn fascicle water potential (ψ pd), conserved water with lowest bulk fascicle diffusive conductance (g), and maintained low g and transpiration (E) during recovery (cycle 6). Enhanced drought acclimation of Pt-inoculated seedlings was independent of plant size and fascicle nutrient content.