Anesthetic Effects on Secondary Dormancy and Phytochrome Responses in Setaria faberi Seeds.
Seeds of giant foxtail (Setaria faberi Herm.) entered secondary dormancy after pretreatment in H(2)O at 35 degrees C. Pretreatment in 0.1 m ethanol, or several other substances with anesthetic properties, prevented secondary dormancy induction. Pretreatment in 0.5 m ethanol inhibited germination in darkness, but germination could be stimulated by a red irradiation. Germination was initially insensitive to light. Two separate responses are indicated. The first, affected by a variety of substances and low (0.1 m or less) concentrations of ethanol, is related to anesthetic effects and prevention of secondary dormancy. The second, induction of response to red irradiation, is caused by 0.5 m ethanol and some closely related substances. The anesthetic effect is accomplished within the first 8 hours of imbibition while the phytochrome induction effect required treatment for more than 24 hours. Both responses were lost if the 35 degrees C imbibition began in H(2)O. Involvement of cell membranes is suggested in the prevention of secondary dormancy by anesthetics.
Taylorson
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Weed Science Laboratory, Agricultural Environmental Quality Institute, Beltsville Agricultural Research Center, Beltsville, Maryland 20705.