Plant biol (Stuttg) 2007; 9(6): 758-765
DOI: 10.1055/s-2007-965079
Research Paper

Georg Thieme Verlag Stuttgart KG · New York

Relationships among Three Pathways for Resource Acquisition and their Contribution to Plant Performance in the Emergent Aquatic Plant Lythrum salicaria (L.)

K. J. Stevens1 , R. L. Peterson2
  • 1Department of Biological Sciences, Institute of Applied Sciences, University of North Texas, P.O. Box 310559, Denton, TX 76203, USA
  • 2Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
Further Information

Publication History

Received: December 31, 2006

Accepted: February 16, 2007

Publication Date:
31 May 2007 (eFirst)

Abstract

Three pathways for resource acquisition exist in the emergent aquatic plant, Lythrum salicaria (L.); a subterranean root system, a free-floating adventitious root system, and arbuscular mycorrhiza (AM) fungal hyphae colonizing subterranean roots. This study examined the relationship(s) among these pathways and their contribution to plant performance. If the free-floating adventitious root system and/or AM fungi contribute to plant growth in wetland habitats, we predicted that their absence would result in a significant reduction in plant performance. Furthermore, if a reduction in resource uptake, effected by an absence of free-floating adventitious roots and/or AM fungi, is compensated for by increased allocation to remaining pathway(s) for resource uptake, we predicted altered patterns of resource allocation among shoots and the remaining pathway(s) for resource uptake. Contrary to our predications, plants experiencing adventitious root removal and/or grown in the absence of AM fungi generally had greater biomass and total shoot height than controls. Similarly, while levels of AM colonization and subterranean root biomass displayed a treatment effect, the observed responses did not correspond with our predictions. This was also true for shoot : subterranean root dry weight ratios. Our results indicate that there is interaction among the 3 pathways for resource acquisition in L. salicaria and an effect on plant performance. The adaptive significance of these characteristics is unclear, highlighting the potential difficulties in extrapolating from terrestrial to aquatic plant species and among aquatic plant species with potentially different life history strategies.