VESICULAR-ARBUSCULAR MYCORRHIZAE IN SALT MARSHES IN NORTH-CAROLINA

The primary objective of this research was to determine if vesicular-a rbuscular (VA) mycorrhizal fungi are associated with the roots of comm on plant species found in North Carolina salt marshes. Root samples of Spartina alterniflora, S. patens, S. cynosuroides, Distichlis spicata , and Juncus roemerianus were collected from eight salt marsh sites. W ith the exception of S. alterniflora, all plant species were mycorrhiz al. A greenhouse experiment was conducted to determine whether unfavor able soil conditions or inherent resistance by the plant inhibited dev elopment of mycorrhizal infection in field-collected S. alterniflora. Spartina alterniflora and S. patens were grown from seeds in soil coll ected from a pure stand of S. alterniflora (soil A) or a mixed stand o f S. patens and D. spicata (soil P). Seedlings were harvested weekly f or 8 wk, and roots were evaluated for infection by mycorrhizal fungi. Seedlings of S. patens were infected when grown for 2 wk in either soi l A or soil P, indicating that soil collected from stands of S. altern iflora did not inhibit mycorrhizal infection in a susceptible host. Pe rcent root length infected in S. patens was always greater in soil P t han in soil A. Seedlings of S. alterniflora were not infected by mycor rhizal fungi in either soil A or soil P. Results of the greenhouse stu dy indicate that S. alterniflora may be resistant to infection by vesi cular-arbuscular mycorrhizal fungi.