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Published on: June 15, 2017
Time threshold for second positive phototropism is decreased by a preirradiation with red light
Janoudi A-K1, R Konjevic, P Apel
1Michigan State University-Department of Energy Plant Research Laboratory, East Lansing 48824.
Abstract:
A second positive phototropic response is exhibited by a plant after the time of irradiation has exceeded a time threshold. The time threshold of dark-grown seedlings is about 15 minutes for Arabidopsis thaliana. This threshold is decreased to about 4 minutes by a 669-nanometer preirradiation. Tobacco (Nicotiana tabacum) seedlings show a similar response. The time threshold of dark-grown seedlings is about 60 minutes for tobacco, and is decreased to about 15 minutes after a preirradiation with either 450- or 669- nanometer light. The existence of a time threshold for second positive phototropism and the dependence of this threshold on the irradiation history of the seedling contribute to the complexity of the fluence response relationship for phototropism.
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