Lesquerella (Lesquerella spp.) is a member of the Brassicaceae and includes herbaceous annual, biennial, and perennial varieties. It is native to North and South America, and 83 of the more than 100 known species are indigenous to North America. Lesquerella species are of interest because of the high hydroxy fatty acid content of their oil (i.e., lesquerolic acid, densipolic acid, and auricolic acid). Different species can be classified by the predominance of each of these fatty acids. Hydroxy fatty acids have numerous potential industrial uses including lubricants, plastics, protective coatings, surfactants, and cosmetics. The current major source of hydroxy fatty acids is recinoleic acid obtained from castor oil. The U.S. annually imports about 41,000 metric tons of castor oil from Brazil and India, at a cost of around $100 million.
Commercialization interests have focused on L. fendleri because of its growth and yield properties. L. fendleri is found throughout the southwestern U.S. (AZ, CO, NM, TX) and northern Mexico. The potential production area in these states is around 1.4 million acres. L. fendleri produces 6 to 25 seeds contained in pods. Seed yields using unimproved varieties in replicated field plots have ranged from 1,000 to 1,350 kg/hectare (900 to 1,200 lbs/ac) and as high as 1,800 kg/ha (1,600 lbs/ac) for improved varieties in test plots. About 25-35% of the L. fendleri seed (by weight) is oil and 55-65% of the oil is a hydroxy fatty acid (lesquerolic acid). The seed coat of L. fendleri also contains a gum which has industrial uses. The seed meal is 30-35% protein, with an amino acid profile similar to soybean. The seed contains 3-7% glucosinolates, which must be deactivated for use as a livestock feed.
Although a perennial, L. fendleri is commercially cultivated as a winter annual. In the southwestern U.S., it is planted by broadcast seeding in the fall (August-September in TX and NM, and October in AZ) using equipment used to plant alfalfa and clover. No yield differences were found between planting on level fields or raised beds. Raised bed production improves insect and weed control and makes it easier to manage salt buildup, but may decrease harvest efficiency. Seeding rates are about 6 to 8 kg/hectare (5 to 7 lbs/ac). Seedlings emerge 8 to 14 days following planting and remain small until February-March, when temperatures begin to increase. Flowering occurs at this time and the seeds develop and mature between March and late May. L . fendleri may be irrigated once every 15-20 days in late February through mid April, and then once every 10 days between late April through mid May (about 25 inches of water total). Seed harvest occurs in mid to late June after the seeds have dried (about 12% moisture).
Conventional combines equipped with small sieves (to prevent excess seed loss) can be used to harvest Lesquerella. Nitrogen applications of around 60-120 kg/ha (about 50-100 lbs/ac) improve seed yields. Weed control is important; as is the case with most new crops, additional herbicides labeled for use on Lesquerella are needed. Estimated costs of producing L. fendleri have ranged from $300 to $550/ac, with differences dependent largely on the extent of irrigation and weed control that is assumed. Improvements in seed yields and management practices are expected to lower these costs.
Research is ongoing to increase seed yields, and oil and fatty acid concentrations. Other efforts include breeding for autofertility (to eliminate the need for insect pollination), and development of plants with upright growth habits to improve harvest efficiency. Most varieties of Lesquerella have an orange-brown seed coat color, which necessitates pigment removal for use in the cosmetics industry. A yellow seed coat variety with reduced pigmentation is available.