INFLUENCE OF AUXINS ON REPRODUCTION OF LEMNA MAJOR

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Abstract
The effect of 3 synthetic auxins[long dash]indole-3-acetic acid, phenylacetic acid and phenylpropionic acid[long dash]on the growth and reproduction of L. major was investigated. The Lemna was grown in purified inorganic salt solns. at pH 4.8 under controlled light and temp. conditions, and free from microorganisms. The auxins, at various cones., sterilized either by autoclave or by Pasteur-Chamberland filters, were added to the salt solns. When added to the inorganic solns. twice weekly, the sterilized auxins failed to increase the reproduction markedly at concs. of 0.1 mg. per liter or lower, and high concs. produced toxic effects. 10 mg. per 1., or slightly more, killed the plants. Intermittent application of solns. of the auxins for 30 min. daily, with the Lemna in the pure inorganic medium for the remainder of the 24 hrs., produced increased reproduction. Both phenylacetic acid and phenylpropionic acid were more effective than indole-3-acetic acid. Plants which had increased their rate of reproduction under the influence of the auxins, returned to the normal rate when replaced in the standard inorganic medium.