Ethanol extracts of the shoot- and root-systems of Helianthus annuus were found to contain an auxin whose chromatographic behaviour was similar to that of indole-3-acetic acid. The concentration of this auxin in the shoots of plants with waterlogged root systems was found after 14 days to have risen to over three times the control value. There followed a drop in auxin content to reach the control figure. This effect of flooding of the root system upon shoot auxin content was correlated with characteristic morphological changes. The effect of flooding on the auxin content of the root system was to delay the fall off in auxin content noted in the root systems of control plants.
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I. D. J. Phillips (1964) studied this question.