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Science 7 March 1969:
Vol. 163. no. 3871, pp. 1067 - 1068
DOI: 10.1126/science.163.3871.1067
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Articles

Ethylene: A Factor in Defoliation Induced by Auxins

Mary Hallaway 1 and Daphne J. Osborne 2

1 Department of Biochemistry, The University, Liverpool, England
2 Agricultural Research Council Unit of Experimental Agronomy, Department of Agriculture, Oxford University, Oxford, England

Aerial sprays of synthetic auxins defoliate many species of tropical trees. Treatment of Euonymus japonica leaves with the n-butyl ester of 2,4-dichlorophenoxyacetic acid causes premature senescence and leaf fall and stimulates ethylene production by the blade 5-to 25-fold. Exposure to ethylene alone similarly accelerates senescence and leaf fall. Evidence indicates that the defoliant action of auxin is mediated through the enhanced amounts of ethylene in the blade.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)