Effects of mycorrhizal fungi and phosphorus on the growth of Celastrus orbiculatus

Effects of mycorrhizal fungi and phosphorus on the growth of Celastrus orbiculatus

Celastrus -- Growth

Mycorrhizal fungi

Plant-fungus relationships

Plants -- Effect of phosphorus on

Lett, Carly Nichole

2008

DeWald, Laura E.

http://rightsstatements.org/vocab/CNE/1.0/

application/pdf

manuscripts (documents)

Text

61793

https://southernappalachiandigitalcollections.org/object/61793

Limited to on-campus users

Invasive exotic plant species can have detrimental effects on the environment into which they become established. Celastrus orbiculatus T. is an exotic weedy species that is invading the eastern United States. C. orbiculatus exploits disturbed areas and once established, can invade into relatively undisturbed forest ecosystems. The native congener, C. scandens, is being outcompeted by C. orbiculatus. Further loss of the native species is occurring at the genetic level from hybridization with C. orbiculatus. The mechanisms that C. orbiculatus utilizes to achieve dominance are not fully understood. I investigated the effect of mycorrhizae on the growth of C orbiculatus using two mycorrhizal fungi treatments (added or absent) and two phosphorus treatments (sufficient or low level). I observed that C orbiculatus forms association with mycorrhizal fungi, regardless of phosphorus level. Plants grown with sufficient phosphorus had significantly higher means for above-ground morphological and physiological variables (photosynthetic rate, total photosynthesis, leaf area, number of leaves, stem length. number of branches, and total biomass) compared to plants grown with low phosphorus. In contrast to above-ground biomass, root biomass was significantly lower when the plants were grown with sufficient phosphorus compared to low phosphorous. The presence of mycorrhizae also had a significant effect on root biomass, with smaller root biomass in plants grown with mycorrhizae compared to plants grown without mycorrhizae. The other traits did not vary significantly between the mycorrhizal treatments. There was a significant interaction (p < 0.05) between phosphorus and mycorrhizal treatments for number of leaves, and biomass of leaves, stems, and shoots. The results or this study indicate that mycorrhizae are a cost to the plant under sufficient phosphorus conditions because above-ground the traits of nonmycorrhizal plants had greater or equal means compared to plants with mycorrhizae. Under low phosphorus conditions, mycorrhizae were beneficial to the plant, although being mycorrhizal did not fully compensate for insufficient phosphorous. These results suggest that in the presence of mycorrhizae or sufficient phosphorus, C. orbiculatus responds with increased growth, which may give it a competitive advantage over native species and facilitate its invasion by outcompeting native species for available resources. Once established with mycorrhizae or in areas of sufficient phosphorus, C. orbiculatus is able to allocate more energy to above-ground growth that facilitates its spread in an environment.

2015-06-04

All rights reserved. For permissions, contact Hunter Library Digital Collections, Western Carolina U, Cullowhee, NC 28723

9303 KB(file size)

viii, 60 leaves(pages)

Western Carolina University Restricted Electronic Theses and Dissertations