Even the sleeving of plants like poinsettia and New Guinea Impatiens can result in leaf and/or flower drop and premature senescence as a response to the stress hormone ethylene. HDC project PC 282 explored the use of rhizobacteria to enhance the shelf-life of pot plants.
Rhizobacteria are a group of bacteria that live in the rhizosphere — a zone that extends a few millimetres around the root hairs. Bacteria can be cultured relatively cheaply, so are a potentially low-cost growing media additive. The chosen bacterium for the study is known to be highly effective in breaking down the ethylene precursor.
Some strains of rhizobacteria have been shown to enhance crop performance in drought conditions because they disrupt ethylene production.
Plants were subjected to a range of stresses including chilling, drought and sleeving the plants to raise humidity. The results demonstrated that the rhizobacteria colonised a range of substrates and that the encouraging effects on plant quality could be exploited commercially.
One of the most spectacular results was with New Guinea Impatiens, which survived drought much better when treated with rhizobacteria.
One extra observation the researchers made during this project was that rhizobacteria promoted development so that plants flowered more quickly and with more flowers initiated. The reduction of ethylene accumulation around the root could also boost root growth in many kinds of crops, leading to improved plant vigour.