Release of lateral buds from apical dominance by glyphosate in soybean glycine max cultivar evans and pea pisum sativum cultivar alaska seedlings
Lee, T.T.
Journal of Plant Growth Regulation 3(4): 227-236
1984
ISSN/ISBN: 0721-7595 Accession: 006306039
Application of a sublethal dose of glyphosate (N-[phosphonomethyl]glycine) to the seedlings of soybean and pea promoted growth of the cotyledonary and other lateral buds. The pattern of the glyphosate-induced lateral bud growth was different from that induced by decapitation. Under the experimental condition, glyphosate did not kill the apical buds. Feeding stem sections of the seedlings with [2-14C]IAA and subsequent analysis of free [2-14C]IAA and metabolite fractions revealed that the glyphosate-treated plants had higher rates of IAA metabolism than the control plants. The treated pea plants metabolized 75% of [2-14C]IAA taken up in the 4-h incubation period compared to 46.5% for the control, an increase of 61%. The increase was small but consistent in soybean seedlings. The glyphosate-treated plants had less free IAA and ethylene than the control plants. The increase of IAA metabolism induced by glyphosate is likely to change the auxin-cytokinin balance and contribute to the release of lateral buds from apical dominance in these plants.