The coming of age for a modern oilseed
GroundCover™ Issue: 101 | Author: Felicity Pritchard
The pace of change in the grains sector is such that it can be easy to lose sight of the extraordinary progress that has been made in a short period of time. Canola growing has evolved quickly in response to R&D
In 1993, the flannelette shirt made a brief appearance as a fashion item outside the farming sector. But far more enduring in that year were several ‘step-changes’ for Australia’s canola industry. It marked the beginning of the first significant impact of modern research, extension and development and a stronger sense of national industry cooperation.
The development of varieties Oscar, Dunkeld and Rainbow – names older canola growers often mention when discussing their experiences with the crop – was a major turning point for the industry in 1992 and 1993, raising the bar for yield and blackleg resistance.
In 1992, two breeding programs in New South Wales and Victoria began working cooperatively. Led by Neil Wratten from the NSW Department of Primary Industries (DPI) and Dr Phil Salisbury from the Victorian DPI, the program supported by the GRDC left a legacy of disease-resistant, high-yielding varieties that laid the foundations for a strong canola industry and more robust crop rotations.
But the real catalyst for an explosion in canola growing was the 1993 release of the first herbicide-tolerant variety. The adage ‘one man’s trash is another’s treasure’ sums it up. In the 1980s, Canadian researchers inadvertently discovered a canola plant (Brassica rapa) resistant to triazine herbicides in a maize crop. Despite Canada’s breeding efforts, triazine-tolerant (TT) canola never took off there due to low yields.
In Western Australia, breeder Dr Narendra Roy attempted to breed TT canola. When South Australian growers became excited by its prospects for charlock-ridden paddocks, breeders anticipated TT varieties could comprise up to 10 per cent of Australia’s canola.
They proved far too modest in their outlook. In 1993, a Victorian DPI and Ag-Seed Research joint venture released Siren, Australia’s first herbicide-tolerant variety. Despite the inherent yield penalty, the crop could compensate with earlier sowing and a lower weed burden due to improved post-emergent weed control. It also helped growers rotate herbicides better.
By 2006, nearly 70 per cent of Australia’s canola crop was triazine tolerant.
The TT varieties set the scene for the development of Clearfield® and Roundup Ready® canola in Australia.
Pacific Seeds released Australia’s first hybrid canola in 1988, and since the mid-1990s research into new types of canola has been ongoing.
Today about half the canola seed sold in Australia is hybrid, with Pioneer Hi-Bred, Canola Breeders, Cargill and Bayer CropScience also making their mark.
Specialty high-stability canola
Specialty varieties, generically known as HOLL (high-oleic/low-linolenic acid oil), have also become increasingly important, with up to 100,000 hectares planted in 2012 as fast-food companies seek healthier and more environmentally sustainable oils. These particular varieties are available through two companies – Nuseed (monola varieties) and Cargill (Victory®).
While canola was taking off in wetter regions in the early 1990s, the crop struggled in the low-rainfall zone. Most varieties had a long growing season and poor drought tolerance.
Meanwhile, Indian mustard (Brassica juncea) had the drought tolerance Mallee growers were yearning for. Scientists realised if the species had the same oil and meal quality as canola, it could be the ideal break crop for these regions, with the bonus of shatter and disease resistance.
After three decades of research, 2007 marked the release of Australia’s first ‘juncea canola’ variety, Dune, by a joint Victorian DPI and Viterra breeding program, supported by the GRDC and led by former Victorian DPI canola breeder Dr Wayne Burton. This was quickly followed by a Clearfield® variety, Oasis CL. The introduction of juncea canola has seen the expansion of canola in regions previously considered unsuited to the crop.
Blackleg remains the number one enemy of Australia’s canola. A low point for the industry was the breakdown of a ‘major’ resistance gene. Previously immune varieties failed in parts of SA in 2003.
This kickstarted a rethink in the way blackleg is managed. Canola varieties with a combination of multiple ‘minor’ resistance genes provide effective resistance.
Recent GRDC-supported research has enabled breeders to identify and understand the genetics of blackleg resistance of Australian canola varieties, the blackleg fungus itself and the way the two interact. This has led to longer-term resistance which provides management strategies for growers.
Since 2007, canola breeding has been in the hands of private companies. The NSW and Victorian DPIs are developing important traits for breeding companies, such as blackleg, shattering and drought tolerance, through four connected projects. An allied project has led to stronger ties and the sharing of Brassica genetic material with India and China.
Canola is now used in farming systems in ways unheard of in 1993. Canola for grain and grazing and canola used for hay in drought are now management options. And if the past two decades are any guide, the coming decades will see continuing technological and agronomic development, turning challenges into opportunities and embedding this increasingly versatile crop in the grains landscape.
Breeding hybrid and open-pollinated canola
Commercially sold canola seed is either hybrid or open-pollinated (OP). OP varieties are self-pollinating. Each plant produces seed that is genetically similar to the parent. In contrast, hybrids involve a labour-intensive and expensive process of cross-pollinating two genetically different ‘male’ and ‘female’ parents.
The cost of breeding hybrids is reflected in the cost of seed. Hybrids have the benefit of hybrid vigour in the first generation (F1), a result of crossing two distinct parents, much like the first cross between a Merino ewe and a Border Leicester ram. This means canola hybrids normally have more vigorous seedlings and produce higher yields than OP varieties.
The breeding objectives for both hybrid and OP canola varieties are similar. Breeders aim to develop high-yielding varieties with good disease resistance and high oil that are adapted to the major canola production regions of Australia.
To produce hybrid canola seed, breeders use two genetically distinct parental lines. The 'female' line consists of plants that develop flowers without pollen (pollen is the 'male' part of a flower). This female line is pollinated with a male line (plants that produce pollen). Production paddocks are divided into blocks of female and male plants in a three-to-one ratio. During flowering, bees transfer pollen from the male blocks of plants to the females. Hybrid (F1) seed produced on the female plants is therefore a cross between the female and the male plants in the paddock. Male plants are destroyed after flowering. Flowers of F1 hybrids grown by farmers have pollen. This is because the original male parent has a ‘fertility-restorer gene’, which is carried by all F1 seeds.
If the seed produced by an F1 hybrid is saved by the farmer and sown the following season, the second-generation (F2) crop is variable. The more genetically different the original hybrid’s parents were, the more uneven the F2 crop will be. Individual plants in F2 crops can have big differences in traits such as blackleg resistance, height, maturity and even herbicide tolerance. Also, a quarter of the plants will be ‘male sterile’, requiring ideal conditions during flowering for cross-pollination, because these plants cannot self-pollinate. Trials with F2 seed have shown significant reductions in yield when using F2 seed compared with F1 hybrid seed.
Two decades of canola research, development and extension
- New South Wales and Victorian breeding programs begin working together in a GRDC-supported national program