Flaxseed is one of humanity’s oldest, and most widely adopted multi-use crops. For over ten thousand years, the oil-rich seeds have been an important source of nutrition for both humans and livestock.
They have also been used for commercial purposes. Flaxseed is often referred to as linseed oil. Linseed oil was highly valued for industrial uses in paints, varnishes, and linoleum flooring. The stem fibers of flax can be processed into linen cloth. Linen was once an important source of clothing, sails, and other textiles throughout Europe, Asia, and the Mediterranean.
A few things reduced the use of flax fiber. The development of the cotton gin allowed cotton to be processed faster, and that became an important competitive market. Cotton eventually overcame linen in popularity.
Linseed oil also was highly valued in paints and varnishes. The invention of synthetic resins and binders after WWII replaced many of these uses of linseed oil.
The growth of the health-foods industry has created new demand and awareness about the benefits of consuming flaxseed. Flax has high levels of omega-3 fatty acids, which benefit cardiac health.
But what if flaxseed could be made even better? This is what researchers at the University of Minnesota are researching by cross breeding with breeding flax wild relatives.
Currently, all cultivated flaxseed is of the annual species Linum usitatissimum. However, the Linum genus has up to 200 species total, many of which are perennial. Developing a perennial version of cultivated flaxseed could have many benefits.
Annual flaxes must be planted yearly, and perennial plants provide continuous living cover. This builds organic matter and prevents soil and nutrient runoff. These could provide ecosystem services like soil retention, water-quality improvement, and pollinator services. All of these are much needed in the corn-soy producing regions of the upper Midwest.
Developing a perennial oilseed capable of replacing annual flax is no easy task. Wild relatives of flax are prolific seed producers. This makes sense in a wild plant. However, wild species also commonly possess a trait called “shattering.” The seed pods automatically split open (shatter), dropping seed all over the ground! While shattering has the obvious advantage of encouraging seedling growth in the wild, it significantly decreases yield under cultivation conditions. How could growers collect all these fallen seeds – versus cultivated flax that is easy to harvest?
Thus, our breeders are searching for natural variation in shattering that will allow them to select non-shattering lines without gene-editing.
Once established, perennial flax plants produce copious numbers of seed pods. They mature relatively early, usually in mid-late July. Starting early in the Spring, new flowers open every morning, and flowering often continues for the duration of the growing season. This continuous flowering quality makes perennial flax a great addition to the ornamental pollinator garden. However, because the seeds don’t have a uniform maturity, that would also make harvest difficult.
Once breeders find a perennial flaxseed that doesn’t shatter and has a uniform maturity, there is still more testing. Even if the seeds “look” the same on the outside, the oils might be different. They still need to be tested to ensure that they have a similar oil profile, and thus the same health benefits as annual flax.
Perennial flax is also being explored for its potential in the cold-hardy landscape industry. It can be used both as a cut flower and garden bedding plant. Many of the species being evaluated are hardy to USDA Zones 3 & 4. They retain green vegetation and flowers well after the first frost.
Future breeding experiments might measure pollinator visitation. This would identify features that encourage pollination, such as flower markings, flower color, or nectar production. Additional experiments geared at breeding for ecosystem services could measure nutrient uptake from agricultural runoff when perennial flax is used as a buffer strip. Finally, perennial flax could one day be evaluated for fiber production for products such as textiles, paper production, and animal bedding.
This long list of potential uses is one of the main reasons why breeders at the University of Minnesota see perennial flax as both a future cash crop, and as part of the solution to ecological challenges the current agricultural system is facing. With time, breeders may be able to give flax the perennial “upgrade” it needs to stay relevant in our changing agroecosystem.
Answered by David Tork, University of Minnesota
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