EFFECTS OF NUTRIENT LEVELS ON THE COLONIZATION OF POA SECUNDA BY ARBUSCULAR MYCORRHIZAL FUNGI AND DARK SEPTATE ENDOPHYTES

Preya Sanjay Sheth

ABSTRACT

Arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are both root-inhabiting fungi that form symbiotic relationships with host plants. Depending on environmental conditions such as soil nutrient levels, the symbiosis can range from mutualistic to parasitic. To examine effects of nutrient levels on the colonization of AMF and DSE, Poa secunda, a native grass species, was grown in potting media inoculated with soil from the root zone of P. secunda individuals, expected to contain both types of root fungi. Soil nutrient level was then manipulated using commercial slow-release fertilizer (Osmocote) to three concentrations: 100% of the recommended rate in high nutrient cones, 50% of the recommended rate in medium nutrient cones, or none with no added nutrients. Host roots were then examined to assess percent colonization by AMF and DSE at each nutrient level. The results showed AMF colonization increased with increasing nutrients, while DSE colonization did not correlate significantly with nutrient levels.

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