Journal Article

Exogenous ethylene inhibits sprout growth in onion bulbs

Gebhard Bufler

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 103, issue 1, pages 23-28
Published in print January 2009 | ISSN: 0305-7364
Published online October 2008 | e-ISSN: 1095-8290 | DOI:
Exogenous ethylene inhibits sprout growth in onion bulbs

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry


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Background and Aims

Exogenous ethylene has recently gained commercial interest as a sprouting inhibitor of onion bulbs. The role of ethylene in dormancy and sprouting of onions, however, is not known.


A cultivar (Allium cepa ‘Copra’) with a true period of dormancy was used. Dormant and sprouting states of onion bulbs were treated with supposedly saturating doses of ethylene or with the ethylene-action inhibitor 1-methylcyclopropene (1-MCP). Initial sprouting was determined during storage at 18 °C by monitoring leaf blade elongation in a specific size class of leaf sheaths. Changes in ATP content and sucrose synthase activity in the sprout leaves, indicators of the sprouting state, were determined. CO2 and ethylene production of onion bulbs during storage were recorded.

Key results

Exogenous ethylene suppressed sprout growth of both dormant and already sprouting onion bulbs by inhibiting leaf blade elongation. In contrast to this growth-inhibiting effect, ethylene stimulated CO2 production by the bulbs about 2-fold. The duration of dormancy was not significantly affected by exogenous ethylene. However, treatment of dormant bulbs with 1-MCP caused premature sprouting.


Exogenous ethylene proved to be a powerful inhibitor of sprout growth in onion bulbs. The dormancy breaking effect of 1-MCP indicates a regulatory role of endogenous ethylene in onion bulb dormancy.

Keywords: Bulb dormancy; Allium cepa; onion; sprout growth; ethylene; CO2 production; respiration; 1-methylcyclopropene

Journal Article.  3853 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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