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Simmondsia chinensis (Link) C.K.Schneid.

Protologue
Ill. Handb. Laubholzk. 2(7): 141 (1907).
Family
Simmondsiaceae
Chromosome number
2n = 26, 52
Vernacular names
Jojoba, goat nut (En). Jojoba (Fr). Jojoba (Po).
Origin and geographic distribution
Jojoba (pronounced ho-hσ-ba) is native to the Sonora and Mojave deserts in California and Arizona in the south-western United States, and adjacent parts of north-western Mexico. The similarity of jojoba wax to sperm-whale oil was first discovered in 1933, and the later ban on the import of sperm-whale oil into the United States in 1971 gave a big impetus to the development of jojoba as an oil crop and to its distribution outside its native habitat. Production has spread to South and Central America, South Africa, Australia and Israel. Experimental plantations have been made in many countries of the drier tropics and subtropics. Extensive trial plantations have been established in Sudan; smaller ones in countries including Burkina Faso and Ghana.
Uses
The seed of jojoba has long been eaten raw or parched by Indians and has been made into a well-flavoured drink similar to coffee. However, its main product now is a liquid wax obtained from the seed. The wax, often referred to as jojoba oil, and many of its derivatives are widely used in making cosmetics such as hair and skin care products, bath oils, soaps and ointments. In medicine, it is applied to alleviate the effects of psoriasis and other skin afflictions. Jojoba wax and especially its sulphur-containing derivatives are stable at high temperatures, which make them suitable as components of industrial oils, as additives in high-pressure and high-temperature lubricants for transformers and gear systems, and as cutting and drawing oils in metal working. The oil or derivatives have potential as a motor fuel. Jojoba methyl-ester fuel runs more quietly than conventional diesel fuel and releases no sulphur. The liquid wax can be converted to a hard wax used e.g. in manufacturing candles. Other applications have been found in the manufacture of linoleum and printing inks. Jojoba oil is not digested by humans and has been tested as a substitute for oils and fats in low-energy foods. However, the oil causes cell damage and is no longer under consideration as a low-calorie dietary oil. The foliage and young twigs are relished by cattle, deer and goats. However, its growth rate is too low to make jojoba an important fodder crop. The presscake from the seed containing 30–35% protein is used as livestock feed. It should form only a small part of the diet as all parts of jojoba contain the appetite-depressing compound simmondsin and even after its removal the presscake is suitable only for ruminants and in limited amounts. On the other hand, simmondsin and the presscake may find application in the feed and pet-food industry as an additive to regulate intake of various feed components. Simmondsin is already marketed in sports-food supplements. The indigenous Americans traditionally use oil extracted from jojoba seed to treat sores and wounds. In Mexico the oil has been used traditionally as a medicine for cancer, kidney disorders, colds, dysuria, obesity, parturition, aching eyes and warts, and to treat baldness. Jojoba is grown in parks and gardens as an ornamental.
Production and international trade
Annual world production of jojoba oil in 2000 was about 1500 t. Production is steadily increasing, currently at a rate of about 10% per year due to increased plantings and maturing plantations. The main producers and exporters are the United States and Argentina; smaller amounts are produced in Australia, Chile, Egypt, Israel, Mexico, Peru and South Africa. In the south-western United States alone, about 17,000 ha of jojoba are under cultivation.
The prices of jojoba seed and jojoba oil fluctuated wildly during the 1980s and 1990s from US$ 25 to less than US$ 2 per kg of seed. Since the late 1990s, the price of jojoba oil has stabilized at about US$ 11 per kg.
Properties
Per 100 g, jojoba seed contains approximately: water 4–5 g, protein 15 g, wax 50–54 g, total carbohydrates 25–30 g, fibre 3–4 g and ash 1–2 g. Jojoba wax is clear golden-yellow and consists mainly of esters of long-chain, mono-unsaturated fatty acids and mono-unsaturated fatty alcohols, mainly eicos-11-enol and eicos-11-enoic acid (both C20) and docos-13-enol and docos-13-enoic acid (both C22) and smaller proportions of octadec-9-enoic acid (C18) and tetracos-15-enol (C24). These esters are rare in plants and substitute for common storage fats. The unsaturated bonds are susceptible to chemical reactions such as sulphurization, saturation and isomerization. The composition of jojoba wax enables it to withstand high temperatures of up to 300°C since it has a flash point of 295°C, a fire point of 338°C, and a low volatility. Jojoba wax has properties similar to the oil secreted by human skin and can be used to lubricate skin and hair for protection against e.g. ultraviolet radiation. The wax is relatively non-toxic, biodegradable and resistant to rancidity.
Jojoba seed meal contains 25–30% crude protein and is rich in dietary fibre. The protein shows an imbalance in the thioamino acids: its cystine content is high, while its methionine content is low. All parts of the plant contain the appetite-depressing toxins simmondsin and related cyanomethylene-cyclohexyl glucosides. The toxic effects of jojoba seem to be predominantly related to the antifeedant and anti-appetent properties of simmondsin 2-ferulate. Seeds contain 2.25–2.34%, seed hulls 0.19%, core wood 0.45%, leaves 0.19–0.23% simmondsin. Simmondsin is especially toxic to non-ruminants and chicken. Rats offered a diet containing 30% jojoba seed meal died of starvation after 2 weeks. A diet containing 10% jojoba seed meal caused a reduction in weight and growth rate, but the rats did not die. When added to the feed of chicken, it causes forced moulting and also interferes with reproduction. In the United States, the Food and Drugs Administration (FDA) allows the addition of 5% detoxified seed cake to cattle feed.
Adulterations and substitutes
Jojoba wax is comparable in properties to the oil of the sperm whale (Physeter macrocephalus and its relatives) and oil from the deep-sea fish ‘orange roughy’ (Hoplostethus atlanticus), but is longer in chain length. While commercial hunting for sperm whale is illegal, orange roughy is commonly caught in deep-sea fishing, but stocks are diminishing rapidly.
Genes encoding for the enzymes involved in long-chain fatty acid and long-chain alcohol production and the gene encoding for wax formation have been isolated from jojoba plants and have been incorporated into Brassica species, which are better suited to large-scale, low-cost production methods.
Description
Evergreen, dioecious, multi-stemmed and profusely branching shrub up to 2.5(–6) m tall, with erect or semi-prostrate stems, young parts usually with soft hairs. Leaves decussately opposite, simple and entire, without stipules, almost sessile; blade ovate to elliptical, 1.5–4 cm Χ 0.5–2 cm, leathery. Flowers unisexual, regular, without petals; male flowers in axillary, dense clusters, yellowish, with c. 5 fringed sepals c. 6 mm long and 8–16 free stamens with short, stout filaments; female flowers usually solitary, greenish, with c. 5 leaf-like sepals c. 13 mm long, ovary superior, 3-celled, styles 3, reflexed. Fruit an ovoid, obtusely triangular capsule, partly enclosed by the enlarged sepals, 3-valved, 1(–3)-seeded. Seed ovoid, 1–1.5(–3) cm long, pale brown to black; cotyledons thick, fleshy.
Other botanical information
Simmondsia, the only genus in the Simmondsiaceae, comprises a single species. Formerly, it has been classified in Buxaceae, but it differs in flower structure, pollen morphology, embryology and phytochemistry.
Growth and development
After germination jojoba forms a deeply penetrating taproot (up to 10 m), which may reach 60 cm before the emergence of the shoot. After the taproot, several deeply penetrating lateral roots are formed, but lateral spread of the root system is limited. A system of finer feeder roots develops closer to the soil surface. Wild plants may develop into small trees, especially in more humid areas; however, they mostly grow into multi-stemmed shrubs. Jojoba leaves may be shed during severe drought but generally live for 2–3 years. Jojoba follows the C3 photosynthetic pathway.
The anatomy of the stem in Simmondsia is distinctive and is characterized by the absence of annual growth rings. Secondary growth occurs in a series of concentric rings. Over time, a series of cambia is formed in the secondary perivascular parenchyma that form new phloem and xylem.
In cultivation, male plants may start flowering 2 years after planting and female ones up to 1 year later. Flowering occurs on new growth only and is initiated by low temperatures. Cultivars with different chilling requirements have been selected. Flower buds may remain dormant until sufficient moisture is available. Prolonged drought may lead to abortion of flower buds and young fruits. Female flowers are mostly produced at alternate nodes, but there are selections that flower at every node.
Jojoba is pollinated by wind. Pollen is produced profusely and flowering male plants are often visited by bees. Pollen grains can travel a distance of over 30 m even with only a light breeze, thereby making pollen distribution very effective. Fruit development takes 3–6 months.
The life span of jojoba may exceed 200 years.
Ecology
The natural habitat of jojoba comprises the open parts of the Sonoran and Mojave semi deserts of southern California, Arizona and north-western Mexico. Its expansion into areas with a climate more favourable to plant growth seems limited by its susceptibility to grazing. In its natural habitat, it occurs in areas up to 1500 m altitude, with annual rainfall of about 250 mm in coastal areas and about 400 mm in inland areas, and with average annual temperatures of 16–26°C. In inland sites with less than 300 mm rainfall, jojoba is only found along temporary watercourses or where run-off water collects. It is tolerant of extreme temperatures; mature plants may tolerate a minimum temperature of –1°C and a maximum of 55°C. Frost damage is common in natural stands and is a major risk in cultivation. Seedlings are very susceptible to frost. The higher extreme temperatures cause scorching of young twigs, leaves and fruits, but not death of plants. Jojoba grows on well-drained sandy, gravelly and neutral to slightly alkaline soils (pH 7.3—8.2) that are often rich in phosphorus. Some selections are tolerant of salinity; they grow and yield well in soils with an electric conductivity of 38 dS/m, or when irrigated with saline water of conductivity 7.3 dS/m.
Cultivated jojoba is grown in areas with 300–750 mm annual rainfall. Rainfall higher than 750 mm is likely to increase the incidence of fungal diseases.
Propagation and planting
Early jojoba plantations were established from seed collected from wild stands, but they were not economically productive. Many new plantations use cuttings or seed from selected plants. Propagation by softwood cuttings from selected shrubs that have been treated with IBA can be used. The cuttings are best planted in a nursery under mist. Cuttings take 25–40 days to strike root. Five-node cuttings taken from actively growing plants give plants with a strongly growing root system. When seed is used, germination is good even after 6 months, but viability is reduced to less than 40% after 10 years of seed storage at ambient conditions. Direct seeding in the field or transplanting of seedlings are used. In a nursery seed is sown preferably in slightly alkaline sand or in vermiculite at temperatures of 27–38°C. Seedlings need irrigation and should be protected from browsing animals. Transplanting should be done very carefully to avoid damage to the root system. Methods of rapid in-vitro clonal propagation have been developed, but subsequent hardening of young plants is still a problem. After land preparation, seedlings are planted at a spacing of about 4.5 m between rows and 2 m within the row, depending on available moisture and mechanization requirements. Where mechanization is not planned, spacing between rows can be less. Hedgerow systems with a reduced spacing of 15 cm within the row have also been suggested and adopted recently.
A proper ratio of female to male plants is 6:1. When seed is used, it is therefore advisable to initially over-plant and rogue out excess males later. The difference in time to flowering between male and female plants allows a first early roguing of male plants.
Management
Weeds should be controlled prior to planting and regularly during the first 3 years after establishment. By that time jojoba plants are large enough to shade-out competing weeds. Where there are grazing or browsing animals, fencing is necessary. Pruning is required to keep the lower branches free from the ground and is generally started when plants are 1–1.5 years old. Later, pruning of female plants is done in intensive cultivation to obtain an upright shape. For male plants, a broader shape is more desirable. Systems of pruning of young plantations grown from cuttings are still being developed. Irrigation greatly increases growth and yields, especially in combination with NPK fertilizers. Irrigation regimes applying 500–1000 mm/year have been used in Israel. Water application should be stopped before the winter to allow the plants to go into dormancy. The response of jojoba to fertilizer application is not well documented.
Diseases and pests
Jojoba is susceptible to fungal wilts such as Verticillium, Fusarium, Pythium and Phytophthora on poorly drained soils. Phytophthora parasitica and Pythium aphanidermatum in particular may cause root rot in plantations. In general, however, the diseases do not cause major economic damage. Fusarium oxysporum, Fusarium solani and other common nursery diseases have been recorded in plants that are raised in the nursery. Grazing animals and rodents are the main pests and in many areas, plantations have to be fenced. A number of insect species feed on jojoba and affect growth or production, but none of them has so far developed into a real pest.
Harvesting
In many countries harvesting is done manually, but in the United States, Australia and Israel harvesting equipment adapted for jojoba is used. In orchard-like plantations or in hedgerow cultivation, seeds can be raked from under the shrubs and then picked up, provided there is no undergrowth. Jojoba seeds do not all mature simultaneously; therefore, more than one harvesting round may be necessary.
Yield
In early plantations, jojoba grown from seed yielded only a few hundred kg of seed/ha and proved not economically viable. In more recent clonal plantations, yields may be about 1000 kg/ha under average rainfed conditions and 2000 kg/ha under irrigation, but yields of up to 4000 kg/ha have been reported.
Handling after harvest
Jojoba seed requires cleaning and drying to 9–10% moisture content before being stored. Extraction of oil from the seed is performed by screw pressing. For many industrial uses, no further refining is needed.
Genetic resources
The largest germplasm collection of jojoba with over 150 accessions is maintained at the USDA-ARS National Arid Land Germplasm Resources Unit, Parlier, California, United States. Several Regional Plant Introduction Stations also maintain some germplasm for evaluation and distribution. Other collections are maintained in Israel and Australia.
Breeding
Genetic variability in jojoba is vast and selection for desirable characters can be carried out in heterogeneous plantations grown from seed of wild plants. Breeding work focuses on yield, oil content and simmondsin content. Additional breeding objectives are a high flower bud to node ratio, frost tolerance and low chilling requirements. Selection of plants that are suitable for mechanical harvesting is also ongoing. Superior clones have been released in Australia, Israel and the United States. High-yielding clones with a low chilling requirement include ‘Q-106’, ‘MS 58–13’ and ‘Gvati’ from Israel.
Prospects
Because of the present high demand for oil, jojoba can be considered a plant with a future, even though the initial great enthusiasm for jojoba as a high-return crop for dry and semi-arid areas has subsided after many failed attempts to grow it successfully and economically. New plantations coming into production will further increase supply and keep prices down. Stiff competition from genetically modified Brassica crops may also negatively influence the market. However, well-managed plantations and the use of high-yielding plant material adapted to local conditions should still give hope. Further testing of jojoba in drier parts of tropical Africa, such as Sudan and the Sahel zone is therefore recommended.
Major references
• Ash, G.J., Albiston, A. & Cother, E.J., 2005. Aspects of jojoba agronomy and management. Advances in Agronomy 85: 409–436.
• Benzioni, A., 1995. Jojoba domestication and commercialization in Israel. Horticultural Reviews 17: 233–266.
• Benzioni, A. & Forti, M., 1989. Jojoba. In: Rφbbelen, G., Downey, R.K. & Ashri, A. (Editors). Oil crops of the world. McGraw-Hill, New York, United States. pp. 448–461.
• Botti, C., Prat, L., Palzkill, D. & Cαnavez, L., 1998. Evaluation of jojoba clones grown under water and salinity stress in Chile. Industrial Crops and Products 9: 39–45.
• Kleiman, R., 1990. Chemistry of new industrial oilseed crops. In: Janick, J. & Simon, J.E. (Editors). Advances in new crops. Timber Press, Portland, Oregon, United States. pp. 196–203.
• Naqvi, H.H. & Ting, I.P., 1990. Jojoba: a unique liquid wax producer from the American desert. In: Janick, J. & Simon, J.E. (Editors). Advances in new crops. Timber Press, Portland, Oregon, United States. pp. 247–251.
• Oyen, L.P.A., 2001. Simmondsia chinensis (Link) C.K. Schneider. In: van der Vossen, H.A.M. & Umali, B.E. (Editors). Plant Resources of South-East Asia No 14. Vegetable oils and fats. Backhuys Publishers, Leiden, Netherlands. pp. 134–138.
• Purcell, H.C., Abbott, T.P., Holster, R.A. & Phillips, B.S., 2000. Simmondsin and wax ester levels in 100 high-yielding jojoba clones. Industrial Crops and Products 12: 151–157.
• Weiss, E.A., 2000. Oilseed crops. 2nd Edition. Blackwell Science, London, United Kingdom. 364 pp.
• Wisniak, J., 1994. Potential uses of jojoba oil and meal - a review. Industrial Crops and Products 3: 43–68.
Other references
• Abbott, T.P., Phillips, W.A., Swezey, J.L., Bennett, G.A. & Kleiman, R., 1990. Large scale detoxification of jojoba meal for cattle feed. In: Proceedings of the 8th International Conference on Jojoba and its uses, held in Asunciσn, Paraguay, June 17–22, 1990. pp. 1–13.
• Bailey, D.C., 1980. Anomalous growth and vegetative anatomy of Simmondsia chinensis. American Journal of Botany 67: 147–162.
• Benzioni, A., Mills, D., Van Boven, M. & Cokelaere, M., 2005. Effect of genotype and environment on the concentration of simmondsin and its derivatives in jojoba seeds and foliage. Industrial Crops and Products 21: 241–249.
• Benzioni, A., Van Boven, M., Ramamoorthya, S. & Mills, D., 2006. Compositional changes in seed and embryo axis of jojoba (Simmondsia chinensis) during germination and seedling emergence. Industrial Crops and Products 23: 297–303.
• Canoira, L., Alcantara, R., Garcia-Martinez, M.J. & Carrasco, J., 2006. Biodiesel from jojoba oil wax: transesterification with methanol and properties as a fuel. Biomass and Bioenergy 30(1): 76–81.
• Cother, E.J., Noble, D., Peters, B.J., Albiston, A. & Ash, G.J., 2004. A new bacterial disease of jojoba (Simmondsia chinensis) caused by Burkholderia andropogonis. Plant Pathology 53(2): 129–135.
• Duke, J.A., 1983. Simmondsia chinensis (Link) C. Schneid. In: Duke, J.A. (Editor). Handbook of energy crops. [Internet] http://www.hort.purdue.edu/ newcrop/duke_energy/ Simmondsia_chinensis.html. Accessed February 2006.
• Foster, M., Jahan, N. & Smith, P., 2005. Emerging animal and plant industries - their value to Australia. Publication 05/154, Rural Industries Research and Development Corporation, Canberra, Australia. 96 pp.
• Hogan, L. & Bemis, W.P., 1984. Buffalo gourd and jojoba: new arid crops. Advances in Agronomy 36: 321–349.
• Kaufman, P.B., Cseke, L.J., Warber, S., Duke, J.S. & Brielman, H.L., 1999. Natural products from plants. CRC Press, Boca Raton, United States. 343 pp.
• Lassner, M.W., Lardizabal, K. & Metz, J.G., 1999. Producing wax esters in transgenic plants by expression of genes derived from jojoba. In: Janick, J. (Editor). Perspectives on new crops and new uses. ASHS Press, Alexandria VA, United States. pp. 196–201.
• Milthorpe, P., 2006. Evaluation of jojoba germplasm in different environments. [Internet] RIRDC Publication no. 05/184. RIRDC, Barton, Australia. 14 pp. http://www.rirdc.gov.au/ reports/NPP/ 05-184.pdf. Accessed December 2006.
• Nimir, M.N. & Ali-Dinar, H.M., 1991. Jojoba, a new cash crop in marginal lands. Acta Horticulturae 270: 369–372.
• Tobares, L., Frati, M., Guzmαn, C. & Maestri, D., 2004. Agronomical and chemical traits as descriptors for discrimination and selection of jojoba (Simmondsia chinensis) clones. Industrial Crops and Products 19(2): 107–111.
• Undersander, D.J., Oelke, E.A., Kaminski, A.R., Doll, J.D., Putnam, D.H., Combs, S.M. & Hanson, C.V., 1990. Jojoba. [Internet] Alternative field crops manual. University of Wisconsin, Center for Alternative Plant & Animal Products & University of Minnesota, Minnesota Extension Service, Madison WI, United States. 5 pp. http://www.hort.purdue.edu/ newcrop/afcm/ jojoba.html. Accessed January, 2006.
• Vaknin, Y., Mills, D. & Benzioni, A., 2003. Pollen production and pollen viability in male jojoba plants. Industrial Crops and Products 18: 117–123.
Sources of illustration
• Oyen, L.P.A., 2001. Simmondsia chinensis (Link) C.K. Schneider. In: van der Vossen, H.A.M. & Umali, B.E. (Editors). Plant Resources of South-East Asia No 14. Vegetable oils and fats. Backhuys Publishers, Leiden, Netherlands. pp. 134–138.
Author(s)
• D.M. Modise
University of South Africa, P.O. Box 392, Pretoria 0003, South Africa
Based on PROSEA 14: ‘Vegetable oils and fats’.

Editors
• H.A.M. van der Vossen
Steenuil 18, 1606 CA Venhuizen, Netherlands
• G.S. Mkamilo
Naliendele Agricultural Research Institute, P.O. Box 509, Mtwara, Tanzania
General editors
• R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
• L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
• A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Modise, D.M., 2007. Simmondsia chinensis (Link) C.K.Schneid. In: van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA 14: Vegetable oils/Olιagineux. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, female flowering branch; 2, female flower; 3, female flower cut lengthwise; 4, ovary cut transversally; 5, male flowering branch; 6, male flower cut lengthwise; 7, seed.
Source: PROSEA



plant habit
obtained from bioimages



leafy branch
obtained from bioimages



bark
obtained from bioimages



male flower
obtained from bioimages



female flower
obtained from bioimages