Bananas Trigger Flowering of Orchids

 

Some native terrestrial orchids only flower in the season after a bushfire.  They are stimulated by the hot gases given off during the fire.  One of those gases is ethylene.  Bananas are shipped down from Queensland to the southern states of Australia as green bananas to stop fruit fly outbreaks.  On arrival they are put in sealed rooms and exposed to ethylene gas.  The bananas ripen a few days later.  Traces of ethylene remain in the banana skin.  Overripe fruit also emits ethylene gas.  Orchid flowers do not last long if ethylene is present in a closed glasshouse.

We know that dormant tubers exposed to ethylene often flower the next season.  The best example is the Hare orchid Leptoceras menziesii.  In summer I put dormant tubers in a small dish in a plastic bag with a banana skin and seal the bag with a rubber band.  The skin may go mouldy so should not touch the tubers.  I leave the bag inside my shed for about 2 weeks then remove the tubers and pot them up.  The exposed plants make leaves almost twice as large as normal tuber leaves.  This procedure should not be carried out with the same plants the following year as they may get exhausted and die out.  I have found results with other shy flowering species are not so reliable.  Maybe they need a stronger does of ethylene.

Article by Les Nesbit

Banana & Banana PeelVol 38 No 5 June 2014

NOSSA Journal

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