Source: CSIRO Information Sheet

CSIRO has had outstanding success in breeding high yielding, high quality cotton with between 80 and 90 per cent of the Australian cotton crop consisting of CSIRO developed varieties. Breeding new varieties continues to be a priority.

The aim of CSIRO's cotton breeding team, led by Dr Greg Constable, is to increase yield and fibre quality. This is addressed by breeding for better disease and insect resistance, herbicide resistance, and regional adaptation using conventional breeding and gene technology.

Disease and insect resistance

By effectively combating disease and insects through resistant varieties cotton yields can be improved and inputs reduced.

Plant characteristics to deter insects

An early development in insect resistance was the okra shaped leaf and reduced leaf hair that deterred Helicoverpa and spider mites. Other plant characteristics that might affect insect attack such as the absence of nectaries that discourages mirids are currently under investigation.

Fusarium

Fusarium is one of the most devastating diseases that affect cotton. Once a paddock is infected it is almost impossible to get rid of it and its presence can reduce yield to an uneconomic level.

CSIRO is setting a standard to ensure all its new varieties have a minimum level of fusarium resistance. It plans to build on this without compromising other positive features of new cotton varieties, to ultimately breed a variety that is completely immune to fusarium.

Other diseases

Resistance to Bacterial Blight and Verticillum Wilt has been achieved and screening of new varieties will ensure this characteristic is maintained.

Varieties resistant to Cotton Bunchy Top are being developed and a watching brief is maintained on other diseases like Alternaria to avoid susceptibility in the breeding program.

Gene technology

Gene technology has been successfully used to breed genetically modified (GM) insect resistant and herbicide resistant CSIRO cotton varieties.

GM varieties have had a major effect on cotton farming. Monsanto's Ingard® reduced pesticide use since 1996 by 50 per cent. Its replacement variety, Bollgard II®, is set to reduce pesticides by 75 per cent.

Roundup Ready® cotton is resistant to the herbicide Roundup® has reduced the use of persistent herbicides in cotton and has been widely adopted by farmers.

Gene technology to improve insect and herbicide resistance will continue to be incorporated into new CSIRO cotton varieties as they become available, and are tested and approved for application.

All gene technology research at CSIRO is conducted with approval from the Office of the Gene Technology Regulator.

Fibre

Fibre quality, particularly strength, length and 'micronaire' (a measure of fineness and maturity), is critical in maximising returns to growers and accessing markets that demand premium quality fibre for specialised applications. Cotton varieties account for a large part of the variability in cotton fibre characters. Management, climate, picking and ginning techniques are also important.

Through breeding better varieties in the last 10 to 15 years, CSIRO has increased cotton fibre strength by 20 per cent and cotton fibre length by about 5 per cent. This has enabled Australian cotton to compete in the higher quality end of the world export market.

Efforts are continuing to improve cotton fibre strength and length while aiming for a fine and mature fibre that consistently falls in the optimal 'mirconaire' range. CSIRO is also using gene technology to help identify genes responsible for fibre development.

Regional adaptation

Cotton is grown in a range of environments in both irrigated and dryland conditions. CSIRO breeds cotton varieties specially suited to the conditions of each region to maximise performance.

The 'Central' region is the largest region of the cotton growing area. It consists of all the major cotton growing valleys including the western Darling Downs, McIntyre, Gwydir, Lower Namoi and the lower Macquarie Valleys. In this area full season, high yielding, disease resistant cottons are required.

Heat tolerance is the main characteristic required for the 'Hot' region of central and western Queensland, and Bourke in NSW.

In the 'Cool' (Eastern Darling Downs, Upper Namoi and Upper Macquarie) and 'Southern' (Lake Tandou, Lachlan Valley and Murrumbidgee) regions marked by shorter seasons and / or cooler temperatures, cotton varieties that mature early are important.

Cotton is also grown under dryland conditions where it is not irrigated. Varieties for this region must be able to cope with the potential stress of limited water which can reduce yield and fibre length. Breeding for dryland conditions focuses on stress tolerance and longer fibres.

Marketing

All CSIRO cotton varieties are commercially available through Cotton Seed Distributors (CSD). Information on this year's varieties is available at www.csd.net.au.