Vesicular-Arbuscular Endomycorrhizal Colonization of Wetland Plants

Mycorrhizal fungi colonize many terrestrial plants and often result in an increased uptake of P and several micronutrients. Little information is available on the relationships among vesicular-arbuscular endomycorrhizae (VAM), aquatic plants, and plant P concentrations. The major objectives of this study were to measure the degree of VAM colonization of wetland plants, and to determine the relationship between colonization and plant P concentrations when sampled from two contrasting water regimes (hydric soil with no surface water and hydric soil with a minimum of 10 cm of surface water). Two semipermanent wetlands in Lake County, South Dakota, were chosen for the study. Water regime did not have a significant effect on total or organic soil P concentration. Vesicular-arbuscular endomycorrhizal spore samples collected from wet soils averaged 5000 spores kg^-1 compared with 2740 spores kg^-1 in dry soils. The eight plant species evaluated to determine VAM colonization were reed canarygrass (Phalaris arundinacea L.), slough sedge (Carex atherodes Spreng.), river bulrush [Scirpus fluviatilis (Torr.) Gray], slender rush (Juncus tenuis Willd.), dogbane (Apocynum cannabinum L.), water smartweed (Polygonum amphibium L.), cattail (Typha X glauca Godr.), and wild licorice (Glycyrrhiza lepidota (Nutt.) Pursh). Vescular-arbuscular endomycorrhizal colonization ranged from 78% (wild licorice) to none (slough sedge and slender rush). Roots from dry areas averaged 27% colonization compared with less than 1% in wet areas. Colonization levels of dogbane and reed canarygrass in dry zones were highly correlated to plant P concentrations. The results of this study indicate that several wetland plant species develop substantial mycorrhizal associations, particularly in relatively dry environments.