Field cress - a new oil crop?
Of the about 7000 species of plants that have been cultivated for consumption, only about 30 crops provide 95% of human food energy needs today. Globally, more than 60% of our energy intake comes from four crops: rice, wheat, maize, and potatoes.
Most of our crops were domesticated thousands of years ago, including emmer wheat in 9000 BC, barley in 8500 BC, rice in 8000 BC, and maize in 7000 BC.
Throughout history, a number of plants have been grown for their oil – both for consumption and for industrial use – and recently for biofuel. Palm and soybean produce by far the largest shares of vegetable oils consumed today, followed by rapeseed and smaller volumes from sunflowers, peanuts, and cotton seed. Among these, the only economically viable oilseed crop in Sweden is rapeseed. Rapeseed was first grownfor use as a lubricant and lamp oil, but nowadays rapeseed (or canola as the edible variety is called) is considered a healthy food oil due to successful breeding in the early seventies. Two Canadian researchers managed to reduce the level of bad-tasting glucosinolates and an unhealthy fatty acid named erucic acid.
The demand for plant oils for food and biodiesel is expected to increase steadily in the coming 20 years. However, the potential for increasing production fromthe existing oilseed crops in Sweden is limited, mainlydue to a limited number of oil crops and their low winter hardiness.
The late Professor Arnulf Merker of SLU identified Lepidium campestre (field cress) as a promising speciesfor domestication. It is a biennial species with an upright stature, synchronous flowering, an average of about 30% more yield than the winter oilseedrape, and maybe most important, a cold-hardiness that allows it to grow even in the northern parts of Sweden. Field trials have shown that field cress has no problem overwintering as far north as Umeå. In the same trilas, only 2% of the rapeseed and 60% of the turnip rape survived. Besides its cold-hardiness and oil-rich seeds, field cress is biennial making ita suitable catch crop that can be sown under cereal crops during spring and produce seeds for harvest the following year. This will reduce tillage and nutrient leaching because the field cress will cover the otherwise bare soil. Nutrient leaching causes groundwater contamination, especially with intensive use of nitrogen-based fertilizers and tillage. Also,unlike many other catch crops, field cress has showna positive effect on the seed yield of companion crops such as barley.
However, some of its properties must be altered in order for the species to be an economically viable oil crop. The oil content of its seeds is about 20% compared to 45% in winter rapeseed, and the oil consists of about 25% erucic acid. Erucic acid is an anti-nutritional fatty acid, and EU regulations have set a maximum limit of 5% erucic acid in food oils. Additionally, the oil is high in polyunsaturated fatty acids (PUFAs) that are very prone to oxidation which makes the oil rancid quickly and thus restricting its use in the food industry. Solving the problems with oil content and quality is only one step on the way toward a high-yielding oil crop because the seeds must also be harvested. Field cress possesses a most unfavourable trait, pod shatter, that causes seeds to fall to the ground before harvest and can result in a loss of up to 50% of the seeds. A plant’s ability to distribute its mature seeds is essential in the wild, but such a trait is useless if youare a farmer trying to harvest as many seeds as possible.
One of the projects in Mistra Biotech is to develop a field cress that is virtually devoid of erucic acid and has significantly reduced PUFAs (linoleic and linolenic acids) but is very rich in oleic acid. This is desirable because the demand for oxidation-stable oils that are high in oleic acid has increased drastically in the food industry recently due to the negative health effects of hydrogenated plant oils.