CSIRO and Cotton Seed Distributors (CSD) have been working together since 1971, with over 116 varieties released to the Australian market.
In 2007, CSIRO and CSD formed Cotton Breeding Australia (CBA), which is a joint venture with a targeted research to facilitate the research and development of future cotton varieties for Australian growers. CBA research is focussed on the future issues and challenges for cotton production in Australia. Both CSD and CSIRO consider the CBA partnership critical in ensuring that cotton remains at the forefront of Australian innovation, well into the future. Given the long lead-time to bring varieties to market, the partnership has been extended to June 2029.
New cotton varieties that are released to the Australian market offer improvements in yield, fibre quality, disease resistance and/or other benefits. Typically, there is a ratio of approximately one commercial variety released for every 20,000 lines assessed in the Breeding Program.
Conventional varieties
Conventional cotton has no genetically modified traits and is the backbone of the breeding program. To bring a conventional variety through to commercial release takes up to ten years. Typically, CSIRO have around four sites located across the industry, with around 1,000 replicated genotypes per site (genotype refers to the genetic characteristics of a plant; whilst phenotype refers to the physical characteristics of a plant). There are over five thousand plots of conventional cotton sown each season. These plots are assessed several times during the growing season and taken through to yield and fibre quality. Decisions are then made to either progress them further or discard them.
Conventional breeding makes up approximately 60% of the breeding program, even though few conventional varieties are now commercially released. Finding sites for trialling conventional varieties is becoming increasingly difficult.There are multiple steps in conventional cotton breeding:
Selected parents crossed
Bulk families developed
Plant selections made
Un-replicated progeny testing
Replicated progeny rows
Preliminary line trials
Advanced line trials
CSD large scale commercial trials
GM traited varieties– For example, cotton containing Roundup Ready Flex® or Bollgard® 3/Roundup Ready Flex®.
In addition to the conventional breeding timelines of ten + years, traited lines can take an additional six to eight years of development. CSIRO typically has around16 traited trial sites across the Australian cotton industry, with up to 500 genotypes per site.
Disease screening
Each season, CSIRO also sows a number of Verticillium screening nurseries (typically with 150 + genotypes per site) and Fusarium (FOV) screening sites (typically with up to 3,000 genotypes per site). This field screening is also backed up with controlled environment bioassay testing (greenhouse or growth room), but field trials are considered more reliable to assess disease resistance.
Commercial trials
The final step in the process prior to commercialisation is assessing variety performance in commercial growing conditions in CSD’s large scales trials. The new candidate lines are grown alongside existing varieties and are taken through to full commercial picking, ginning and classing. The data collected by CSD is in addition to CSIRO’s small plot results.
Seed increase, or bulking up the seed quantity, is undertaken by CSD whilst assessing potential new varieties is underway in CSD large scale trials prior to potential release to the Australian cotton market.
Therefore, in addition to the 10 to 16 years taken to breed a new variety, a further two to three years are required for CSD to produce enough seed for commercial sales.