Non photosynthetic interactions of bentazone with plant growth and development

Miller, PR, 1989. Non photosynthetic interactions of bentazone with plant growth and development. PhD, Nottingham Trent University.

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Abstract

A range of bioassays were performed to establish the non photosynthetic PGR activity of the herbicide bentazone. In bioassays for auxin activity bentazone stimulated growth of primary leaf petioles, cotyledonary internode and first lateral of light-grown Phaseolus vulgaris over a 12d period, and stimulated elongation of etiolated Avena sativa coleoptile segments within 1h. These responses each had similar concentration dependence to, but were smaller in magnitude, than responses of the same tissues to exogenous IAA. IAA and bentazone-enhanced coleoptile elongation was similarly sensitive to a range of inhibitors. In Phaseolus vulgaris tissues, Avena sativa coleoptile segments, and Lepidium sativum roots, IAA and bentazone produced significant interactions, bentazone reducing IAA responses at high (optimum) concentrations, but enhancing IAA responses when both compounds were simultaneously applied at low concentrations. In a bioassay for gibberellin activity, bentazone inhibited elongation of juvenile internodes of intact, light-grown Pisum sativum similarly to IAA, and inhibited exogenous GA3-enhanced internode elongation, over 5d, again similarly to IAA. Investigation of a proposed plasmalemma mediated mechanism of action, the same as, or similar to that of IAA, found bentazone active in promoting H efflux from etiolated Avena coleoptile segments, again similar to, but smaller in magnitude than IAA responses, and with clear interaction between the two compounds, particularly when bentazone was at low concentration. It is proposed that IAA and bentazone are active at the same, or a closely associated, plasmalemma bound auxin receptor, and that short and long term observed interactions may be accounted for by considering interactions at the initial binding site. Speculative models for these interactions are presented. The value of considerations of interactions at binding sites in herbicide action and interaction studies are discussed.

Item Type:	Thesis
Creators:	Miller, P.R.
Date:	1989
ISBN:	9781369313987
Identifiers:	Number Type PQ10183117 Other
Rights:	This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the author's prior written consent.
Divisions:	Schools > School of Animal, Rural and Environmental Sciences
Record created by:	Jeremy Silvester
Date Added:	17 Sep 2020 15:42
Last Modified:	19 Jul 2023 10:14
URI:	https://irep.ntu.ac.uk/id/eprint/40778

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