E.A. Oelke1, E.S. Oplinger2, C.V. Hanson1, K.A. Kelling2
1Department of Agronomy and Plant Genetics, and Center for Alternative Plant and Animal Products, University of Minnesota, St. Paul, MN 55108.
Meadowfoam (Limnanthes alba Benth.) is a low growing herbaceous winter annual that is adapted to poorly drained soils. Limnanthes means marshflower and the common name "Meadowfoam" arose due to the appearance, at full bloom, of its solid canopy of creamy white flowers. Meadowfoam is native to northern California, southern Oregon, and Vancouver Island, British Columbia. The oil from meadowfoam seed has unique chemical properties that make it one of the most stable vegetable oils known.
Research and development of meadowfoam began in the late 1950s as the result of a USDA search for plants that might provide a renewable source of raw materials for industry. Commercial development began in 1980 on an experimental 35 acre farm scale operation in Oregon. However, the lack of consistent funding has slowed the development of both the agronomic and the oil utilization aspects of this unique renewable oil resource.
Meadowfoam seeds (nutlets) contain 20 to 30% oil. Meadowfoam oil contains three previously unknown long chain fatty acids. The oil is over 90% C20 to C22 fatty acids and is most similar to high euric acid rapeseed oil. Rapeseed oil is slightly more saturated than meadowfoam oil. Meadowfoam oil can be chemically transformed into a liquid wax ester that is a substitute for sperm whale oil and jojoba oil. Meadowfoam oil can also be converted to a light colored premium grade solid wax, a sulfur polymer factice potentially valuable to the rubber industry, or used as a lubricant, detergent or plasticizer. Potential industrial applications for meadowfoam oil are currently being researched by USDA-ARS at the New Crops Research Center in Peoria, Illinois.
After the oil is removed by crushing the seed and utilizing a solvent extraction process, the remaining meal may be used as a feed source. Meadowfoam meal fed to beef cattle at levels up to 25% of total intake had no negative impact on weight gain. Use of the meal for other livestock may require steam cooking or using a lower percentage of meal in the total feed supply. Further research in this area is necessary.
Meadowfoam is an erect annual herb with one or more branches arising from the base and grows to a height of 10 to 18 in. It has a shallow fibrous root system that allows for easy transplanting at any stage of growth. Leaves are pinnately dissected, flowers are regular, perfect, and usually conspicuous on axillary peduncles.
Meadowfoam requires insect pollination to set seed. Cool, wet, or windy weather during flowering limits the activity of pollinators and therefore reduces the number of fertilized flowers. Meadowfoam is not self pollinating because the male reproductive organs mature before the female organs are mature (pollen is released from the anthers before the stigma of the flower is receptive). This plant adaptation is common for enhancing cross pollination. Two or three colonies of bees per acre of meadowfoam are needed for adequate pollination (note: other flowering plants in the vicinity may be preferred by pollinators). The development of self pollinating varieties should increase yield potential.
Meadowfoam has a very low tolerance to water stress and therefore is well adapted to the cool wet Mediterranean climate of the Pacific Northwest. Many areas in the U.S. may be able to produce meadowfoam if, in the future, market demands make oil production profitable. Under conditions of below average precipitation in the Willamette Valley, irrigation during flowering and seed development was found to significantly increase yields.
Meadowfoam grows well on most soil types, however sandy soils with low water holding capacity are less favorable under dry conditions.
Secondary dormancy of the seed occurs at temperatures over 60¡F when the seed is imbibing water. It also appears that light may be a factor in initiating dormancy. Seed sown on the soil surface shows a higher level of secondary dormancy than seed that is covered with soil.
The seedbed should be moderately fine to allow for uniform seed placement.
Meadowfoam is normally grown as a winter annual in the Pacific Northwest. Planting in October after soil temperatures in the seed zone are below 60°F aids in germination. Warmer soil temperatures promote seed dormancy which can lead to poor germination and poor stand establishment. Meadowfoam has been grown as a spring planted annual in areas where winter temperatures are too cold to allow fall planting.
Plant densities of 3 to 4 plants/square ft have resulted in the highest yields. Different conditions at planting time and soil type will affect the seeding rate necessary to achieve this plant density. Seeding rates of 15 to 40 lb/acre have been successful. Good seed-soil contact is required for uniform germination. Drilling seed 1/4 to 3/4 in. deep in 3 to 7 in. rows, is recommended over broadcast seeding followed by incorporation, although both methods have produced successful yields.
Although no fertility research has been conducted on Meadowfoam in Minnesota or Wisconsin, some work from the Pacific NW has shown that nitrogen fertilization increases yield, however it may result in delayed flowering and a decrease in the percent oil content of the seed. Soil pH should range between 5.5 and 6.0, with fertilizer requirements of 40 to 60 lb N/acre, 20 lb P2O5/acre at soil tests of 10 to 20 ppm P, and 20 to 30 lb K2O/acre at soil tests of 80 to 100 ppm K. Excess fertilization which promotes lush vegetative growth may create conditions favorable for diseases.
Variety selection began with selected individuals within the species L. alba. The first, 'Foamore' selected for its upright habit, was named by Oregon State University in 1975. It is 10 to 12 in. tall and yields 800 to 1300 lb/acre. 'Mermaid' released in 1985 by Oregon State University is 12 to 14 in. tall, upright, and has good seed retention. Seed stock is controlled by the Oregon Meadowfoam Growers Association (OMGA). Varieties from the cross of L. floccosa × L. alba shows increased seed size, increased oil content, and reduced lodging. Continued development of new higher yielding varieties is expected.
Competition from weeds can severely reduce the yield of meadowfoam. Two herbicides; propachlor at 4 lb/acre (broad spectrum) and diclofop at 1 lb/acre (post-emergent, grass control) have been shown to be effective for weed control in meadowfoam fields but, are NOT registered for use at this time.
Botrytis cinerea affects stems, leaves, and flowers and results in shriveled seed and reduced yields. Botrytis destroyed commercial meadowfoam fields in 1983 and in 1984 in the Pacific Northwest. Fungicide applied at 40 to 50% bloom has been shown to be effective, however no fungicides are currently approved for commercial use.
Insect pests have not been a problem in meadowfoam fields. However insects collected in association with meadowfoam plants include the spotted cucumber beetle, nitidulid beetle, seed bug, and seed-feeding Carabidae beetle.
Meadowfoam can be harvested with the same equipment used in grass seed production. The crop is cut when 90% of the seeds are mature and the stems are greenish-yellow. Windrowing early in the morning with a dew present helps to prevent shattering. Meadowfoam is allowed to dry in the swath for 7 to 10 days or to a seed moisture content of 12 to 16%. Threshing is more efficient when the moisture content of the seed and other plant material is low. Combine efficiency is increased by slow ground speed, high cylinder speed, close cylinder clearance, open sieves, and high wind speed. Post harvest, meadowfoam fields have little plant residue remaining.
Meadowfoam oil is very stable in storage. Production of meadowfoam oil has been stockpiled for sale to foreign and domestic buyers mostly in the cosmetic and personal care products industries.
Research plots have produced over 2000 lb/acre of seed. Unfortunately commercial fields have generally yielded less than 750 lb/acre largely due to disease and pollination problems. Future development of new varieties should lead to consistently higher yields.
Meadowfoam oil is in direct competition with rapeseed oil for the high volume industrial oilseed market. Penetration into this market requires that the price of meadowfoam oil be competitive and the supply dependable. The price of meadowfoam oil was as high as $4.00/lb in 1986 but has been declining and is expected to reach $2.00/lb due to increased efficiency of large scale production and the value of using higher yielding varieties.
Product development that takes advantage of the unique long chain fatty acids found in meadowfoam oil would tend to lead to a high value, low volume market that would certainly accelerate the development of full scale production.
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