Hunter Johnson, Jr., Extension Vegetable Specialist

University of California, Riverside

Botanical Information

Jicama (pronounced he'-cama) is a tropical legume which produces an edible fleshy taproot. The above-ground part of the plant is a vigorous spreading prostrate vine which reaches several feet in diameter. Flowers, either blue or white, and pods similar to lima beans are produced on fully developed plants. There are several species of jicama, but the one found in our markets is Pachyrrizus erosus. There are two cultivated forms P. erosus: jicama de agua and jicama de leche. The latter has an elongated root and milky juice. The agua form has a top-shaped to oblate root, a translucent juice, and is the preferred form for market.

A Crop for California?

All of the jicama found in our markets is produced in Mexico. There has been recurrent interest in producing this crop in California, but only undocumented reports of successes. The known efforts to grow jicama have resulted in luxurious vine growth with prolific flowering and pod production but with low quality fibrous taproots. A long, warm growing season under relatively short day length is required to initiate good quality fleshy root development. Recent research (Cotter and Gomez) confirms this and suggests that sufficient variability may exist within the species to allow selection for longer day types. Since the temperature and day length conditions required to mature good quality roots of currently available cultivars do not exist in the United States (except perhaps in the south of Florida), it is unlikely that current cultivars of jicama can be grown successfully in this country. Any plantings which may have produced good roots in past years in California very likely occurred under unusually warm October and November conditions, a weather phenomenon which is rare even in the southern part of the state.

Jicama is propagated by seed. The seeds are squarish in shape, brown or tan in color, with the general characteristics of other bean seed. Sandy loam soil with good drainage is the best choice to obtain smooth roots. Rows should be two to three feet apart with plants eight to 10 inches apart in the row. Information on fertilizer requirements is limited, but one source suggests 1,500 pounds per acre of 6-6-12. In the tropics, three to six months are required to develop marketable roots, depending on temperature at the growing location. The literature on jicama indicates that, for best root production, flowers should be removed at an early stage. It is stated that flower removal causes the root to expand in diameter. Yields are in the range of five to seven tons per acre.

Culinary Uses

Jicama is most commonly eaten in the fresh form. After peeling to remove the brown fibrous outer tissue, the crisp white fleshy portion can be sliced, diced, or cut into strips for use as a garnish, in salads, or with dips. It is frequently served as a snack sprinkled with lime or lemon juice and a dash of chili powder. Jicama remains crisp after boiling and serves as a textural substitute for water chestnuts. Jicama is similar to white potatoes in food value, but with slightly lower total food energy (calories). In the tropical production areas, the immature pods are sometimes cooked and eaten, but mature pods are said to be toxic. Mature seeds contain a fairly high content of rotenone, and at one time, commercial culture of jicama was considered as a source of this insecticide.

References

Clausen, R. T. 1944. A botanical study of the yam beans (Pachyrrhizus). Cornell University Agricultural Experiment Station, Memoir 264.

Cotter, D. J., and R. E. Gomez. 1979. Daylength effect on root development of jicama (Pachyrrhizus erosus Urban). HortSci. 14(6):733-734.

Hansberry, R., R. T. Clausen, and L. B. Norton. 1947. Variations in the chemical composition and insecticidal properties of the yam bean. J. Agr. Res. 74:55-64.

Herklots, G.A.C. 1972. Vegetables in South-East Asia. George Allen and Unwin Ltd., London. pp. 449-452.

Miller, C. D., and B. Branthoover. 1957. Nutritive values of some Hawaii foods. Hawaii Agr. Exp. Sta. Circ. 52: p. 16.

Norton, L. B. 1943. Rotenone in the yam bean (Pacyrrhizus erosus). J. Amer. Chem. Soc. 65:2259.

Norton, L. B., and R. Hansberry. 1945. Constituents of the insecticidal resin of the yam bean (Pacyrrhizus erosus). Amer. Chem. Soc. J. 67:1609:1614.

Porterfield, W. M. 1939. The yam bean as a source of food in China. New York Bot. Gard. J. 40:107-108.

_________________________. 1951. The principal Chinese vegetable foods and food plants of Chinatown markets. Econ. Bot. 5(1):12.

Schroeder, C. A. 1967. The jicama, a rootcrop from Mexico. Proc. Trop. Reg., Amer. Soc. Hort. Sco. 11:65-71.

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Additional info:

The mature root is lifted out of the ground with a modified plow, selected for uniformity of shape and freedom from defects and placed into baskets, which are carried and emptied into a truck or trailer and transported in bulk under ambient conditions to markets.

Jicama destined for the US market is handled through intermediaries in Tijuana. There, the jicama is unloaded, washed with water, selected, trimmed (the taproot is cut off), packed into crates of about 50 lb each and dipped into a solution reported to be about 10% calcium hypochlorite to sanitize and whiten the root. The crates are drained, palletized, and transported again under ambient conditions to US markets such as the LA market and nearby distributors. From there it may be reselected and repacked and shipped to points around the US on mixed load shipments. In Mexico jicama may be stored in the ground for up to 3 months.

Store in cool, dry area. Too much moisture will cause mold. Common postharvest problems are sprouting during storage, decay and dehydration.

USDA recommends storage at 55-65 F (13-18 C) and 65-70% relative humidity for up to 1 to 2 months. Recent research at UC Davis has concluded that jicama is chilling sensitive, and that storage below 12.5 C causes major problems. The development of chilling injury depends not only upon the temperature, but also the length of storage. For example, with storage up to 2 weeks at 10 C the roots appear capable of recovery. By three weeks, however, the roots were permanently and seriously damaged. At storage temperatures of 0 C serious chilling damage occurred with one week. At 5 C damage occurred within 1 to 2 weeks.

Jicama has 20 mg. Vitamin C, 1.4 grams of protein, and 15 mg of calcium per 100 grams of edible raw portion.

Orozco, Warner; Cantwell, Marita and Luis Hernandez. Postharvest Studies on Jicama (Pachyrrhizus erosus) I. Quality and physiological changes of roots stored at different temperatures. Progress Report. Dept. of Vegetable Crops, Mann Laboratory, University of California, Davis. July 1990.

Vegetables and Vegetable Products. USDA Agriculture Handbook No. 8-11. Revised Sept. 1984.

Tropical Products Transport Handbook. USDA Agriculture Handbook No. 668. 1987.

Based on work by Hunter Johnson, Jr., Retired Extension Vegetable Specialist, Univ. of California, Riverside; and Warner Orozco, Marita Cantwell and Luis Hernandez, Dept. of Vegetable Crops, Mann Laboratory, University of California, Davis.

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