Boron fertilization, ectomycorrhizal colonization, and growth of Pinusechinata seedlings

Shortleaf pine (Pinusechinata Mill.) seedlings inoculated with Pisolithustinctorius (Pers.) Coker and Couch or left uninoculated were grown in book planters for 16 weeks. Seedlings were fertilized with 25 μg mL−1 of borate applied to the foliage as a mist, to the soil as a solution, or to both the foliage and the soil. B applied to the foliage or to the soil significantly increased ectomycorrhizal colonization of roots and seedling growth. Growth of uninoculated seedlings was not enhanced by B fertilization. The lack of growth response of uninoculated seedlings as contrasted with increased infection and growth of inoculated seedlings suggests that B affects the fungal symbiont or the plant host–symbiont combination to a greater extent than the plant host alone.