Indoleacetic Acid and Abscisic Acid Antagonism: II. On the Phytochrome-Mediated Attachment of Barley Root Tips on Glass.
The effects of low concentrations (10 nm or less) of indoleacetic acid and abscisic acid on the phytochrome-mediated attachment of barley root (Hordeum vulgare L., var. Compana) tips on glass have been found to be opposite to those reported for mung bean root tips. Unlike their effects on mung bean root tips, indoleacetic acid causes attachment while abscisic acid causes detachment of barley root tips. Both hormones specifically and rapidly counteract the action of the other. No effect on the photoreversibility of attachment was observed when several gibberellins, cytokinins, and ethylene were added to the assay medium over a wide concentration range.
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United States Soils Laboratory, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland 20705.