Behaviour of Helianthus annuus L.: an ethogram for sunflower, and the effect of potential competitors on soil nutrient patch use

• Author / Creator

  Ljubotina, Megan Kathryn

• Individual organisms mediate their relationship with their environment through behaviour, which can have consequences at higher levels of biological organization such as populations and communities. Plants express diverse behaviours in response to their environments, but many aspects of behaviour remain unexplored in plants. In this thesis, I address behavioural questions about plants using common sunflower, Helianthus annuus L.
  First, I present an ethogram for H. annuus, a catalogue of behaviours observed in the species, here drawn from the literature. The intent of this ethogram was to provide a behavioural perspective on the biology of a widespread and well-known plant, showing that plants in general take in and respond to information about their environments in diverse ways.
  Second, using an experimental approach, I test how root foraging behaviour in H. annuus is impacted by the location of high nutrient soil patches relative to competitors. For plants, patchiness of soil resources is typical, with high nutrient patches in a matrix of relatively low nutrient soil. Plants commonly respond to high nutrient patches by proliferating roots within them, thereby preferentially increasing investment in and use of these patches. Although patch use is often contingent on social aspects of the environment in other taxa, we understand little about how patch use in plants may be altered by competitors. Here, I measured temporal dynamics of patch use by sunflowers grown alone with sole access to a high quality patch, by sunflowers sharing a high quality patch with an equidistant neighbouring plant, and by sunflowers located in closer proximity to a high quality patch relative to a neighbouring plant. I also compared patch use by sunflowers grown alone with two high quality patches to use by sunflowers grown with two high quality patches and a neighbour, so that one patch was equidistant to a neighbour and the other was in close relative proximity to the focal plant. As expected, sunflowers grown alone preferentially used (grew more roots in) high nutrient patches than lower nutrient background soil. Patch use changed depending on the specifics of the social environment: plants that shared equal access to a single high quality patch no longer preferentially used the patch, but plants in closer proximity to a high quality patch than a neighbour increased use relative to plants grown alone. We suggest that these responses may allow sunflowers to avoid competition in highly contested patches equidistant to neighbours, but to also pre-empt resources in high quality patches that they are closer to and therefore typically have first access to. By contrast, plants with access to two patches decreased use of shared patches but did not increase use of high quality patches they were in closer proximity to. This result is consistent with general predictions about competitive behaviour being less important in less resource-limited environments. These results show that at least for sunflower, root foraging responses are socially contingent, and plants may account for the possibility of monopolizing limited resources in the near future to inform foraging decisions.

• Subjects / Keywords

  • plant behaviour
  • root behaviour
  • ethogram
  • nutrient foraging
  • behaviour

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-1dx4-1c74

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.