THE OCCURRENCE OF VESICULAR-ARBUSCULAR MYCORRHIZAE ON FLORIDA RANGE GRASSES

The role of vesicular-arbuscular mycorrhizae (VAM) in plant growth, development, and survival is well documented in agronomic crops, but little information exists with respect to Florida range grasses. The objective of this study was to determine if mycorrhizae fungi occur on native range grasses and to quantify mycorrhizae fungi in soil from rangeland. From a five-county area of southwest Florida, chalky bluestem (Andropogon capillipes Nash.), creeping bluestem (Schizachyrium stoloniferum Nash.), broomsedge bluestem (Andropogon virginicus L.), and wiregrass (Aristida stricta Michx.) whole plants and soil were collected from 13-20 Sep. 1990. Root colonization by VAM for all species ranged from 6 to 28% and the total VAM spore density ranged from 23 to 265/100 g of dried soil. Major VAM fungi species collected in this study were Glomus spp. and Gigaspora spp. Percentage root colonization by VAM for all species except wiregrass tended to be similar among locations, while VAM spore density differed among locations for all grasses. Decreaser range grasses (plant species that decrease in relative amount in response to overgrazing; i.e., chalky and creeping bluestem) had higher average percentage root colonization than the increaser grasses (plant species that increase in relative amount; i.e., wiregrass, broomsedge).