Endomycorrhizal colonization of yellow-poplar seedlings

Objectives were to determine (1) whether two species of endomycorrhizae exhibited similar degrees of colonization in nursery grown yellow-poplar seedlings, (2) whether all seedlings within treated flats were equally colonized, and (3) whether the two fungi acted synergistically when present in combination. Sterilized growth medium was infested with spores and hyphae of Glomus mosseae, Glomus fasciculatus, or G. mosseae + G. fasciculatus. Approximately 150 yellow-poplar seeds from each of five seed sources were sown in each treated and control flat. After 12 weeks, five seedlings from each seed source were harvested and processed for microscopic observation. Fifty microscopic fields (3mm²) from each root were analyzed for the presence of intracellular hyphal coils, vesicles and arbuscules. None were found in the control. Fungal structures were observed in seedling roots in all treatments. However, colonization was considerably greater with G. mosseae as the only symbiont. Colonization was less extensive when G. mosseae was mixed with G. fasciculatus. The degree of colonization within roots from the same treatment varied from 0 - 64%.