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Brigham Young University (2019)

Use of Plant Growth Regulators to Expand the Period of Sagebrush Seed Germination and Reduce the Risk of Restoration Failure : Laboratory Trials

Keefer, Chelsea Elizabeth,

Titre : Use of Plant Growth Regulators to Expand the Period of Sagebrush Seed Germination and Reduce the Risk of Restoration Failure : Laboratory Trials

Auteur : Keefer, Chelsea Elizabeth,

Université de soutenance : Brigham Young University

Grade : Master of Science (MS) 2019

Résumé
Seed germination during unhospitable environmental conditions can be a major barrier to direct seeding efforts in dryland systems. In the sagebrush steppe, Artemisia tridentata Nutt. ssp. wyomingensis and Artemisia arbuscula are important shrub species that are being used in restoration, but seeding success is highly sporadic due to inter-annual and intra-seasonal weather variability. Altering and expanding the period of germination, as a form of bet-hedging, may improve plant establishment. Our objective was to determine if we could expand the period of germination using plant growth regulators (PGRs) applied in a conglomerated seed coating treatment. In a laboratory study, the seed was either left untreated, conglomerated separately with two concentrations of a germination inhibitor, abscisic acid (ABA), or with two different germination promoters, gibberellic acid (GA3) and 1-Aminocyclopropane carboxylic acid (ACC), a precursor to ethylene. Seeds were incubated in a loam soil at five constant temperatures (5-25 C) for approximately three months. Results indicate that seed treatments with PGRs can delay or speed germination. The greatest response to the seed treatments was observed at 5 C. For example, at this temperature PGRs delayed the time for 25% of the seeds to germinate by a maximum of 35 and 21 d and decreased this time by 5 and 25 d for A. t. ssp. Wyomingensis and A. arbuscula, respectively. Field studies are needed to determine if the bet-hedging strategy developed in this study will increase the likelihood that some seeds will germinate during periods that are more favorable for plant establishment.

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