Wilting of an orchid flower

Orchid flowers are very sensitive to handling and road transportation. It was found that when the anther cap was removed (emasculation) the flower would start wilting within the period of a few days. To get some more understanding of this phenomenon the plant was placed in a cuvette and the release of ethylene was measured using a laser-based detector.

After taking away the anther cap an immediate rise in ethylene release was observed. The wilting process started after two days and coincided with a second increase in the ethylene production.

These results can be explained by the role of ethylene as a plant hormone. Small amounts of ethylene can give rise to large effects. The first ethylene peak was produced by the central column because of the removal of the anther cap. The ethylene is transported to the other parts of the plant where it triggers the wilting process of the flower that could be observed two day later. This dramatic reaction of the flower to removal of the anther cap can be traced back to the function the flower fulfils in a natural environment. When an insect has entered the flower to gather nectar, it may touch the anther cap and take away the pollinia. At that moment the flower does not serve the reproduction of the plant anymore and it should die. The signal to start wilting is initiated by the removal of the anther cap and is mediated by the first ethylene peak.