Growth and Iron Sequestering of Pin Oak (Quercus Palustris) Seedlings Inoculated with Soil Containing Ectomycorrhizal Fungi
Richard J. Hauer and Jeffrey O. Dawson
Abstract: Ectomycorrhiza formation, biomass production, and iron accumulation were determined for pin oak (Quercus palustris) seedlings grown for 2 years in acidic (5.5 pH) or alkaline (7.5 pH) media and inoculated with soil from 1 of 3 sites: 1) a native pin oak forest, 2) an urban site with chlorotic pin oak trees, or 3) an urban site with non-chlorotic pin oak trees. Ectomycorrhiza formation on pin oak roots was similar for soil inocula from all 3 sites, similar for both pH treatments, and lacking on non-ectomycorrhizal seedlings that had been inoculated with autoclaved soil. Seedling biomass was greater in the acidic medium than the alkaline medium. Inoculated seedlings in the alkaline treatment had greater biomass than uninfected control seedlings inoculated with autoclaved soil in the alkaline treatment. The mean iron concentration of seedlings grown in the acidic medium (54.3 ppm) was significantly greater than that of seedlings grown in the alkaline medium (48.7 ppm). Inoculated seedlings had similar mean leaf iron concentrations despite pH differences (49.3 ppm under acidic conditions and 52.7 ppm under alkaline conditions). Mean leaf iron concentration was lowest for the uninoculated seedlings in alkaline medium (44.8 ppm), suggesting that ectomycorrhizae contribute to iron accumulation in pin oak under alkaline soil conditions. Results indicate that ectomycorrhizae influence both growth and iron sequestering under iron-limiting conditions and that some urban soils harbor infective pin oak eetomycorrhizal fungi.