D.J. Undersander1, E.A. Oelke2, A.R. Kaminski1, J.D. Doll1, D.H. Putnam2, S.M. Combs1, and C.V. Hanson2
1Department of Agronomy, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
Jojoba (Simmodsia chinensis (Link) Schneider) is a perennial woody shrub native to the semiarid regions of southern Arizona, southern California and northwestern Mexico. Jojoba (pronounced ho-HO-ba) is being cultivated to provide a renewable source of a unique high-quality oil.
Native Americans extracted the oil from jojoba seeds to treat sores and wounds centuries ago. Collection and processing of seed from naturally occurring stands in the early 1970s marked the beginning of jojoba domestication. In addition, the ban on the importation of sperm whale products in 1971 led to the discovery that jojoba oil is in many regards superior to sperm oil for applications in the cosmetics and other industries.
Today, 40,000 acres of jojoba are under cultivation in the southwestern U.S. Much of the interest in jojoba worldwide is the result of the plant's ability to survive in a harsh desert environment. The utilization of marginal land that will not support more conventional agricultural crops could become a major asset to the global agricultural economy.
The oldest commercial jojoba plantings in the U.S. were established in the late 1970s, and present production of jojoba oil is in the range of thousands of tons per year. The major world producers are the United States and Mexico, with considerable quantities of oil being exported to Japan and Europe.
Jojoba seed contains a light-gold colored liquid wax ester which is the primary storage lipid of the plant. This is unlike conventional oilseed crops, such as soybean, corn, olive, or peanut which produce oils as the primary storage lipid. Jojoba wax (called oil) makes up 50% of the seed's dry weight. The physical properties of jojoba oil are: high viscosity, high flash and fire point, high dielectric constant, high stability and low volatility. Its composition is little affected by temperatures up to 570°F (300°C). Jojoba oil contains straight- chained C20 and C22 fatty acids and alcohols and two unsaturated bonds, which make the oil susceptible to many different types of chemical manipulations. The extracted oil is relatively pure, non-toxic, biodegradable, and resistant to rancidity.
Most jojoba oil produced in the U.S. today is sold at a high price for use in cosmetics and hair care products. As many as 300 products containing jojoba have appeared in the U.S. in recent years. As the supply of oil increases and price decreases, more uses will become economically feasible. For example, the viscosity index of jojoba oil is much higher than that of petrolium oil; therefore, it may be used as a high temperature, high pressure lubricant. The stability of jojoba oil makes it attractive to the electronic and computer industries. And since jojoba oil contains no cholesterol or triglycerides and is not broken down by normal metabolic pathways, it may become an important low-calorie oil for human consumption. The oil can be used as an antifoam agent in antibiotics production and as a treatment for skin disorders. Other proposed uses include candles, plasticizers, detergents, fire retardents, transformer oil, and for the leather industry.
The meal contains up to 30% protein, but toxic compounds (simmondsins) make it currently hazardous as an animal feed.
Jojoba is a woody evergreen shrub or small multi-stemmed tree that typically grows to a height of 10 to 15 ft. Leaves are opposite, oval or lanceolate, gray green, and have a waxy cuticle that reduces moisture loss. The plant develops one or a few long tap roots (up to 40 ft) that can supply water and minerals from far below the soil surface.
Jojoba is usually dioecious (male and female flowers are borne on separate plants). Female flowers are small, pale green and commonly solitary or in clusters at the nodes. Male flowers are yellow, larger, and occur in clusters. Pollination occurs via wind or insect.
The fruit is a green capsule which encloses up to three seeds. When ripe (3 to 6 months after fertilization) the capsule splits and reveals the seed, which is brown, wrinkled and about the size of a small olive (300 to 1,000 seeds/lb). Seed production is generally limited until the fourth year of growth.
Jojoba is best suited to areas that are frost free and is not grown in the northern midwest. When temperatures drop below 20°F, flowers and terminal portions of young branches of most jojoba plants are damaged. During early seedling development, excessive cold may kill an entire plantation. Frost may not damage taller plants to the same degree, but it can reduce yield. Jojoba is very tolerant of high temperatures.
Natural stands of jojoba occur in areas that receive 3 to 18 in. of precipitation annually. Irrigation has produced more luxuriant vegetative growth, but it is not known whether this increased growth results in higher seed yield. Jojoba requires the most water during late winter and early spring.
Most wild jojoba populations occur on coarse, light or medium textured soils with good drainage and good water infiltration. Planting on heavy soil results in later blooming, slower growth and more problems with fungal diseases.
Jojoba can be planted by direct seeding or by transplanting seedlings to the field. In the southwestern U.S. many growers prefer direct seeding because it is less expensive, faster and requires less hand labor. Seed can be germinated in vermiculite or sand at about 80°F. Emergence occurs in 15 to 20 days, and the seedlings are ready for transplanting when they are 6 to 12 in. tall (8 to 10 weeks). Emergence from direct-seeded fields occurs in 15 to 20 days. Propagation from clones or from tissue culture is a more rapid method of varietal improvement.
Jojoba plantations are established by clearing and leveling a site prior to seeding or planting seedlings, rooted cuttings or plantlets produced from tissue culture.
Jojoba can be seeded or transplanted to the field when the soil temperature reaches 70°F. Low soil temperature may delay emergence by as much as 2 to 3 months.
Seeds are planted 1 in. deep, and emergence usually occurs within 20 days. The soil should be kept moist but not wet through emergence.
Individual seeds or seedlings are planted 12 to 18 in. apart in rows. Spacing between rows depends on the harvester to be used. With hand harvesting and cultivation, rows can be as close as 10 ft.
To obtain the proper female:male ratio (6:1), it is advisable to over-plant (7 to 9 lb/acre of seeds) and rogue out excess males later. As male plants flower, they should be thinned out to 1 male every 40 ft on the row. As female plants flower, usually in the third year, any slow-growing or unproductive plants are thinned out, leaving 1 female plant every 2 to 3 ft on the row.
Little information is available on the response of cultivated jojoba to lime or fertilizer applications. Jojoba grows wild on soils of marginal fertility with soil pH ranging from 5 to 8. The soils that jojoba is adapted to in the semiarid regions of Arizona, southern California and northwestern Mexico are generally slightly alkaline and have native high potassium levels. Based on this, one might assume that for best growth, soils should have a pH of 6 or more and available K levels of at least 100 ppm. Apply enough dolomitic lime according to soil test recommendations to raise soil pH to 6. Approximately 10 to 15 pounds of potash fertilizer should be applied if available K levels are less than 100 ppm. Yield trials conducted in California have not shown any improvement in vegetative growth with the addition of nitrogen or phosphorus, therefore no additional N or P2O5 fertilizers are recommended.
There are no improved varieties of jojoba. Some yield components that vary among wild jojoba stands include: seed size, oil content, number of flowers per node, early flowering, precocious seed production (starting before the fifth year), consistent high production from year to year, upright growth habit, and degree of frost tolerance. Work is underway to select for desired traits and plants suitable for mechanical harvest.
Weeds must be controlled early in the establishment of the plantation. Weed control prior to planting and/or cultivation between rows during growth is needed until the jojoba plant is large enough to shade competing plants. No herbicides are registered for use on jojoba in the midwestern United States.
On poorly drained soil, jojoba is susceptible to fungal wilts, including Verticillium, Fusarium, Pithium and Phytopthora.
More than 100 species of insects have been identified on jojoba, but few cause known economic damage. Infestations of spider mites, grasshoppers, and thrips may result in yield losses.
Fences may be necessary to eliminate browsing by wild animals who find the plant very palatable. This has been a major factor in the distribution of jojoba.
All seeds on a jojoba shrub do not mature at the same time, and more than one harvest may be necessary. Most jojoba is currently harvested by hand. Over-the-row fruit and berry harvesting equipment is adaptable to jojoba harvesting.
Jojoba seed that has been dried to around 10% moisture and protected from pest damage will keep for several years.
Jojoba generally does not produce an economically useful yield until the fourth or fifth year after planting. Seed yields in natural stands of jojoba range from a few seeds to as much as 30 lb of clean, dry seed per plant. Production of seed varies greatly from plant to plant in a stand and from year to year for a particular plant.
Currently, the average yield of commercial jojoba plantations is less than 300 lb/acre. Plantations that were established with selected higher yielding clones are capable of producing up to 800 lb/acre. Crop improvement programs at the University of California-Riverside and the University of Arizona-Tucson are actively researching consistent productivity.
In 1978, the cost of establishing jojoba in the southwestern U.S. (the first 3 years) was estimated to be $1,157/acre. Low yields and frost damage have resulted in financial losses for many farmers and investors. Successful long-term production of jojoba depends on improved yield and a strong market. Industry is typically hesitant to invest in new technology involving an agriculturally produced resource until a steady and continued supply of that resource can be demonstrated. The value of jojoba oil as an alternative industrial oil with multiple applications and as a replacement for non-renewable fossil petroleum has been demonstrated.