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  • Author or Editor: G. R. Leather x
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Abstract

Six species of seedling trees were foliar-treated in greenhouse experiments with 7 - ox ab icyclo(2,2,l)heptane-2,3-dicarboxylic acid (endothall) mixed with (2 chloroethyl) phosphonic acid (ethephon). A range of 75 to 100% abscission was obtained within 14 days with little or. no damage except on Chinese elm (Ulmus parvifolia Jacq.).

Open Access

Abstract

7-Oxabicyclo (2.2.1) heptane, 2-3-dicarboxylic acid (endothall) alone was not an effective chemical abscissor of bean leaves (Phaseolus vulgaris L. cv. Red Kidney) until a concn of 30 to 40 mg/liter was attained, but in the presence of 800 mg/liter (2-chloroethyl)phosphonic acid (ethephon) abscission began at 5 mg/liter endothall. Low pH (1.5) significantly lowered the break strength of abscission zone explants of leaves sprayed with ethephon and endothall compared to pH 6.0, and endogenous ethylene production from endothall alone was higher at pH 1.5 than pH 6.0.

Open Access

Abstract

Over 100 years ago, German investigators reported that defoliation was associated with the proximity of leaking illuminating gas mains (15), and it remained for Neliubov to show that the active component of illuminating gas was ethylene (23). Later, La Rue (20) reported that auxin played a role in abscission because addition of auxin delayed the separation of plant parts. Support for the central role for auxin in abscission stems from the observation that a reduction of auxin content precedes abscission (22). Ethylene was shown to be produced by plant tissue by Gane (14), and increases in the rate of ethylene production during ripening and fruit abscission was shown by Nelson (24) and, during leaf abscission, by Jackson and Osborne (18). A third abscission regulator was introduced when Ohkuma and Addicott (25) demonstrated the presence of abscisic acid (ABA) in rapidly abscissing cotton bolls.

Open Access