ARS | Publication request: A comparative study of buoyancy duration in Carya aquatica, Carya illinoinensis, and Carya x lecontei seeds

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 12, 2011
Publication Date: March 3, 2011
Citation: Kroh, G.E., Svoboda, J.R., Grauke, L.J., Grusak, M.A. 2011. A comparative study of buoyancy duration in Carya aquatica, Carya illinoinensis, and Carya x lecontei seeds [abstract]. Texas Academy of Sciences 114th Annual Meeting. p. 52.

Technical Abstract: A characteristic of Carya species is that their seeds are buoyant. The different physical properties of Carya seeds, such as oil composition and air-filled cavities, may contribute to this buoyancy. Carya aquatica (water hickory) and Carya illinoinensis (pecan) trees are found along streams and rivers, suggesting that seed buoyancy may facilitate hydrochory (i.e., dispersal by water). This study focused on seeds of C. aquatica, C. illinoinensis, and C. x lecontei, the latter being an interspecific hybrid of pecan and water hickory. We measured the initial densities of seeds from several genotypes of each of the species and hybrid, the rate of change of these densities over time (while placed in water), and the duration that seeds remained buoyant. For the buoyancy duration tests, seeds were placed in a water-filled tub, in which a submersible pump was used to mimic the movement of water in a stream. Seeds were monitored daily until a density of greater than 1.0 g/mL was reached and buoyancy was lost. Average initial seed densities (based on several genotypes) ranged from 0.85–1.05 g/mL for pecan, 0.77–0.85 g/mL for C. aquatica, and 0.60–0.89 g/mL for C. x lecontei. The change in density over time (seeds in water) was comparable across the pecan relatives, while buoyancy duration varied, being associated with initial seed density. These data will be used to assess seed dispersal capabilities of Carya relatives and to discuss the potential of this phenomenon in promoting Carya gene flow and genetic diversity across riverine landscapes.