Designer eucalypts for urban landscapes
University of Adelaide researchers are working with the Australian nursery industry to produce 'designer eucalypts' more suitable for our home gardens and urban landscapes than many trees currently available.
Led by Dr Kate Delaporte at the University's Waite Campus, the researchers and nurseries are developing a new way of propagating eucalypts that aims to be cheaper and more efficient, and, importantly, will enable production of plants with a particular flower colour, size and form.
"Eucalypts provide habitat for native birds, insects and animals and, often, are resilient to our harsh extremes - there is great potential for them to be used more in our gardens and urban areas. But there are only a small number of these specially-improved eucalypts currently available to gardeners in Australia," says Dr Delaporte.
"Eucalypts produce a lot of viable seed but their inherent variability means that there is no guarantee that a tree with red flowers will produce seed that grows into new trees that have red flowers. Only through producing improved cultivars, propagated using methods like grafting and tissue culture, can we guarantee that the buyer knows what they are getting in terms of flower colour and tree size and shape. Most garden plants are propagated this way."
Before potential new cultivars can be released on the market, they need to be grown over some years to test for commercially desirable characters - height and shape suitable for urban environments, attractive flowers and buds - and to ensure there aren't any undesirable characters, like limb dropping or excessive growth.
Tissue culture is a fast and reliable way of propagating promising cultivars, but in the past, tissue culture from mature eucalypts has been extremely difficult. The new method being developed involves germinating seeds in culture and then propagating the lines from the initial seedlings.
The researchers have some promising lines of trees that can be propagated through this method which are still going through field trials.
"If we can successfully develop an economically viable method of clonal propagation through tissue culture, it will be the key that opens the door to a whole range of beautiful new designer plants," says Dr Delaporte. "There's so much opportunity to bring new eucalypts into the garden, all with bright flower colours, attractive foliage, bark and nuts, that are a good small size."
The tissue culture research is building on a long-term project going since 1996, the Ornamental Eucalypt Development Program. This work has led to the new varieties released last year, Nullarbor Rose and Nullarbor Lime, produced through grafting.