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Boise State University (2022)

Drought Tolerance of Artemisia Tridentata in Response to Herbivory and Mycorrhizal Colonization

Geisler, Mathew

Titre : Drought Tolerance of Artemisia Tridentata in Response to Herbivory and Mycorrhizal Colonization

Auteur : Geisler, Mathew

Université de soutenance : Boise State University

Grade : Master of Science (MS) in Biology 2022

Résumé partiel
Interactions with other organisms can affect a plant’s ability to cope with drought. The re-establishment of Artemisia tridentata, a keystone species of the sagebrush steppe, is often limited by summer drought. This study investigated the effect of two biotic factors, herbivory and symbiosis with arbuscular mycorrhizal fungi (AMF), on the drought tolerance of Artemisia tridentata ssp. wyomingensis (Wyoming big sagebrush) seedlings. For this purpose, I conducted two separate but concurrent field experiments. The herbivory experiment had three treatments : seedlings without tree protectors and seedlings within Vexar or metal-mesh tree protectors. In the mycorrhizal experiment, all seedlings were within metal-mesh tree protectors, and the experiment had two treatments : without and with the addition of trap culture inoculum. The effects of the treatments were evaluated on seedling survival, leaf water potential, stomatal conductance, and inflorescence development. To better assess the impact of AMF colonization on drought tolerance, I also conducted greenhouse experiments. These experiments investigated whether AMF colonization affected the decline in stomatal conductance and photosynthesis induced by drought.

Herbivory damage, presumably caused by ground squirrels, mainly occurred in early spring, about five months after outplanting. Most seedlings recovered from this damage, but herbivory was associated with higher mortality during the subsequent summer, fall, and winter. Eighteen months after outplanting, the survival in plants within metal protectors was 12 and 39% higher than in those within plastic and no protectors, respectively. In addition, the percentage of lived plants that developed inflorescences was approximately threefold higher in plants with protectors than those without them. The results of this experiment indicate that most plants that suffered herbivory did not die directly from this disturbance but from increased susceptibility to abiotic stresses, including drought.

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Page publiée le 12 décembre 2022