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Increasing salinity, involving the gradual destruction of productive farmland, pristine forests, underground water reserves, river networks and other elements within our natural environment has created millions of hectares of land in which the original vegetation, or introduced crops and pastures have been destroyed and few plants survive.
 Perhaps the worst affected landscape, the one showing the most obvious signs of the losses being sustained on the salinity battlefield, are the nation's agricultural farmlands. In Western Australia alone, it is estimated that losses in productivity due to salinity are in the vicinity of $200 million a year.
Hundreds of salt lakes and thousands of salt scalds  almost all farmers have at least one, or the potential for one, on their property attest to the insidious expansion of the advancing enemy.
Farmers, biologists, and environmental and agricultural scientists have tried a variety of weapons to contain, and hopefully defeat the enemy, but so far have enjoyed only limited success.
This lack of success is partly due to the fact that the financial costs of fighting salinity can be extremely high and farmers receive little, if any, return from the thousands of dollars they must invest in tree-planting, fencing, contouring and other farm-management strategies designed to control the salinity problem on their properties.
Therein lies the raison d'etre behind research currently being undertaken by Associate Professor Jen McComb at the School of Biological and Environmental Sciences at Murdoch University.
Professor McComb believes strategies need to be developed from which farmers will receive a direct economic benefit by revegetating salt-affected land. The trees being planted must not only serve the recognised purposes of shade, shelter and lowering the water table and thus removing salt from surface soil and water they must also be capable of being harvested for financial benefit.
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The challenge has been to find tree species, which will happily grow in a saline landscape, that can also be used for timber or paper production.
Unfortunately no such ideal tree exists, but if the best qualities of two of our eucalypts River Red Gums (Eucalyptus camaldulensis) and Tasmanian Blue Gums (Eucalyptus globulus) could be combined, farmers could have a valuable resource they require. River Red Gums can survive in water-logged, salty landscapes and Tasmanian Blue Gums produce high levels of good quality pulp suitable for paper production.
A hybrid between these two trees may carry the desirable characteristics of the respective parents salt-tolerance and good pulp yield and quality.
In 1992, with financial assistance from Alcoa Australia, Professor McComb and PhD candidate Rachel Oddie began the cross pollination that ultimately led to the production of the first hybrid
E. camaldulensis x globulus seedlings. Male pollen from E. globulus was supplied by North Eucalypt Technologies in Burnie, Tasmania.
The hybrid seedlings were subsequently placed in water-filled troughs and subjected to increasing saline concentrations. Those seedlings showing the best salt-tolerance were selected for cloning and provided the parent plants for the generation of hundreds of cloned salt-resistant hybrid E. camaldulensis x globulus seedlings.
Approximately 900 of these were planted on each of two salty areas one on Beverley farmer Chris Ayres' property in the heart of the Western Australian wheatbelt, and another on WA Agriculture's Mount Barker Research Station in the far south of the State.
Professor McComb said the hybrid trees were planted in different zones within the salt scalds from 'absolutely horrible land in the core of the saline scald' to better quality land on its fringe.
"It appears, like other plants, they won't grow right in the saline scald, but they're doing well in the soil that is characterised by the presence of barley grass one of the most salt-tolerant species of plants," she said.
The trees have now been growing in the field for more than two years and their success has attracted considerable, widespread interest.
Late last year Queensland biotechnology company ForBio became involved in the project. ForBio is one of the few companies in Australia which uses a cost-saving robot to facilitate the plant-tissue culture stage of plant production.
The company has seen a use for its technology in the production of salt-tolerant E. camaldulensis x globulus tree crops.
"A robot would be ideal for producing the many thousands of plants that will be needed for successful tree crops on farms in the future," said Professor McComb.
"ForBio is also interested in using the progeny from our hybrids to look at the DNA structure to see if there's a DNA probe that is associated with salt-tolerance.
"If there is, it will save a huge amount of time which is currently taken up testing for salt tolerance in lengthy, and not necessarily accurate, laboratory procedures and field tests.
"With other collaborators, ForBio will also be looking for DNA probes for such qualities as fast growth rate, good pulp quality and suitable structural form."
The work is being incorporated in a major national research project called XylonovA which is aimed at 'enhancing environments deemed unfit for productive use'.
The research project was recently awarded a grant from the Rural Industries Research and Development Corporation (RIRDC). This, along with continuing support from Alcoa and North Eucalypt Technologies, will allow production and field testing of more of the hybrids in more locations, including the Murray Darling Basin and Tasmania.
See also
Computer technology to help fight salinity
Fighting for forests and farmlands
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