VESICULAR-ARBUSCULAR ENDOMYCORRHIZAL COLONIZATION OF WETLAND PLANTS

Mycorrhizal fungi colonize many terrestrial plants and often result in an increased uptake of P and several n-micronutrients. Little informa tion is available on the relationships among vesicular-arbuscular endo mycorrhizae (VAM), aquatic plants, and plant P concentrations. The maj or objectives of this study were to measure the degree of VAM coloniza tion of wetland plants, and to determine the relationship between colo nization 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 La ke County, South Dakota, were chosen for the study. Water regime did n ot 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 colonizatio n 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 Go dr.), and wild licorice (Glycyrrhiza lepidota (Nutt.) Pursh). Vescular -arbuscular endomycorrhizal colonization ranged from 78% (wild licoric e) to none (slough sedge and slender rush). Roots from dry areas avera ged 27% colonization compared with less than 1% in wet areas. Coloniza tion levels of dogbane and reed canarygrass in dry zones were highly c orrelated to plant P concentrations. The results of this study indicat e that several wetland plant species develop substantial mycorrhizal a ssociations, particularly in relatively dry environments.