PARENT SESSION
Poster Session 37: Forest Ecology.
Thursday, August 5 Presentations from 5:00 PM to 6:30 PM, Exhibit Hall A 1.
Phosphorus and potassium leakage from mycorrhizal and uninoculated roots of Quercus douglasii.
Hynes, Meagan*,1, Zasoski, Robert 1, Bledsoe, Caroline 1, 1 University of California, Davis, Davis, CA, USA
ABSTRACT- The exact nature of nutrient transfer within Common Mycorrhizal Networks is unclear. A closed system, in which nutrients pass from plant to fungi to plant, has been hypothesized. However, leakage of nutrients from roots into the soil and subsequent uptake by nearby roots is an alternatively feasible scheme for nutrient transfer. We believe mycorrhizal inoculation reduces leakiness, due to a variety of mechanisms. Our research has focused on testing this alternative hypothesis, concerning leakage in root systems. Using Quercus douglasii (blue oak) seedlings that were either inoculated with ectomycorrhizal fungi or uninoculated, we examined the root leakage of phosphorus and potassium chemical analogs in the adjacent soil. The experiment took place in a growth chamber using eight month old seedlings that had been inoculated for 4 months with an ectomycorrhizal fungus known to form a symbiosis with blue oaks found in the Sierra Foothills of Northern California. A phosphorus analog, arsenate, and two potassium analogs, rubidium chloride and cesium chloride, were applied foliarly. The amounts of nutrients leaked from the inoculated and uninoculated seedlings were analyzed. We extracted the analogs from soil using ammonium acetate. The solution was then analyzed using an Atomic Absorption Spectrophotometer. Our results to date show there was a significant difference between the inoculated and uninoculated roots concerning the cesium chloride. The blue oaks with a mycorrhizal fungi association leaked less cesium chloride into the surrounding soil than the uninoculated seedlings. Due to the mobile nature of cesium chloride, leakage into the soil was expected. Preliminary results for rubidium chloride show less leakage overall into the soil. Arsenate levels in the soil were almost undetectable.
Key words: pottasium and phosphorus, Quercus douglasii, mycorrhizae, nutrient transfer and leakage