EFFECT OF MANGANESE IONS ON THE IAA-INDUCED ELONGATION OF AVENA COLEOPTILE SECTIONS INHIBITED BY SOME ORGANIC ACIDS

1.Organic acids, such as citric, -ketoglutaric, succinic, fumaricand L-malic acids, inhibit the IAA-induced growth of Avena coleoptilesections. But pyruvic acid has no effect on the growth. 2.High concentrations of MnCl₂ (for example 10^–3 m) alleviatethe inhibition due to L-malic, -ketoglutaric, succinic and fumaricacids, but not that due to D-malic, tartaric and malonic acids. 3.A mechanism of the alleviating effect of Mn⁺⁺ on the inhibitiondue to the organic acids is discussed with the reference tothe activating effect of Mn⁺⁺ on "malic" enzyme. ¹Contribution No. 6 from the Botanical Gardens. Faculty of Science,University of Tokyo, Koishikawa, Tokyo.