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Breeding oilseed flax for fibre, too

Flax breeders are aiming to develop an oilseed variety that can also capture new value-added opportunities for the straw.

Researchers are aiming to select flax varieties with good oilseed characteristics and a high fibre content. Photos Courtesy Of N. Coetzee, University of Saskatchewan.

Researchers at the University of Saskatchewan are working on one of the key factors needed to capture growing value added opportunities for flax straw. “The main aim of our research is to develop an oilseed variety with a fibre concentration that is consistent enough to make it worthwhile for the processor to purchase the straw from the farmer, take it to their factory and process it,” explains PhD student Natalie Coetzee. “And at the same time, the farmer should be able to get the extra economic benefit from the fibre without the need for complicated or expensive practices.”

On the Canadian prairies, flax is grown primarily for the seed and managing the straw presents a problem. The tough fibres are difficult to chop and spread during combining. If left on the field, the durable straw can clog up equipment during subsequent field operations. And burning off the straw leads to the loss of nutrients and soil organic matter, and to the risk of safety and air quality concerns.

Selling the straw turns the problem of strong, durable fibre into an advantage. That is especially true if the processors are nearby, so transportation costs are low, and if the processors sell the processed fibre into higher end markets so they are able to pay more for straw with specific characteristics that meet their processing requirements.

The traditional use of flax in the linen industry requires long fibres and those long fibres come from a different type of flax plant than the varieties grown for seed. But many of the new fibre markets can use the shorter fibres found in oilseed flax straw. Coetzee says, “The new uses for the flax fibre include things like specialized paper, such as paper money or cigarette paper, particle board, textiles and insulation – you can use flax fibre for pretty much anything that fibreglass is used for. You might one day find the panels of your car made of flax fibre.”

Many of the new fibre markets can use the type of fibres found in oilseed flax straw.

Coetzee and her colleagues at the University of Saskatchewan, guided by her supervisor Dr. Gordon Rowland, are completing a three year field study to investigate the heritability of fibre content in oilseed flax varieties. She says, “We are using our existing breeding population of oilseed flax because the oil will still be the primary outcome of the crop. We wanted to see if we have variation in the fibre content in that population because obviously it’s very hard to select for fibre if there’s not a lot of variation in the population itself.”

Several preliminary findings from the first two years of the study indicate that the researchers will very likely be able to select varieties with both good oilseed characteristics and a high fibre content. First of all, there is quite a lot of variation in the fibre content. Second, some of the individual plants have very high fibre levels. And third, the variation in fibre content does not seem to be tied to the seed yield; consequently a breeding line with more fibre will not necessarily have poorer oilseed characteristics.

“Because we are selecting for a different type of fibre, rather than the long fibres needed for linen, we hoped that there wouldn’t be a strong negative correlation between the seed yield and the fibre content, and that does seem to be playing out,” notes Coetzee.

At present, the researchers are focussing on the amount of fibre in the straw, rather than looking for any specific fibre characteristics. They are using near-infrared spectroscopy to quickly and accurately measure the fibre content.

The field trials are showing quite a lot of variation in the fibre content of the existing oilseed breeding population, including some plants with very high fibre levels.

Coetzee says their potential straw buyers are currently exploring various possible uses and have not yet determined which specific fibre characteristics would be best for which uses. “At some point if the buyers decide they want a specific type of fibre, then we can look at selecting for that.” She adds, “Flax seems to have quite a wide range of fibres that can be developed. At the Biofiber Industry Advancement Workshop in 2005, one of the presenters had a whole range of different types of fibre that they had separated out from oilseed flax straw.”

As expected from the results of previous research, the fibre content in the field study varies by year and by location, indicating that environmental conditions have a very significant effect on fibre content. The researchers have not yet pinpointed which particular environmental factors have the greatest influence.

Coetzee explains that the strong influence of environmental conditions makes it all the more important to develop flax varieties that have a stable fibre content under a wide range of conditions. “Just as with any other crop, there will be years when you have a poor fibre crop. So the best we can do is to make sure that we have a flax variety that gives us as high fibre yields as possible most of the time. The advantage with this crop is that, because the oil is the main aim, if the fibre fails, it’s not necessarily going to mean the crop has failed.”

The study is using typical production practices for oilseed flax, so the fibre content does not rely on special practices. In a separate project, another University of Saskatchewan graduate student is assessing the effects of different crop management practices on fibre content. Previous studies have indicated that fibre content is influenced by such factors as seeding date, seeding rate and harvesting practices, along with the flaxseed variety.

Based of the field results, Coetzee and her colleagues will be assessing a number of different ways of selecting breeding lines for good yields of both seed and fibre, to find out which selection strategy works best. Her research is supported by the Natural Sciences and Engineering Research Council of Canada, the Saskatchewan Flax Development Commission and the University of Saskatchewan.