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Page 105 Ulluco In many highland areas of the Andes, ulluco (Ullucus tuberosus) is a staple, and in a few it is the predominant root crop. One of the most striking foods in the markets, its tubers are so brightly colored—yellow, pink, red, purple, even candy striped—and their waxy skins are so shiny that they seem like botanical jewels or plastic fakes. Many are shaped like small potatoes but others are curiously long and curved like crooked sausages. 1 ; Their skin is thin and soft and needs no peeling before eating. The white to lemon-yellow flesh has a smooth, silky texture with a nutty taste. Some types are gummy when raw, but in cooking, this characteristic is reduced or lost. Indeed, a major appeal of ulluco is its crisp texture, which remains even when cooked. The future of ulluco (pronounced oo-yoo-koh) seems particularly bright. In the Andes, demand is on the increase, and its attractive tubers are likely to prove popular elsewhere. The plant is easy to grow, resists frost, is moderately drought tolerant, and produces reasonable yields in marginal soils. Although it has attracted little modern agronomic attention, ulluco is one of the few Indian crops to have been enthusiastically accepted by those of Hispanic descent. This ancient tuber is now sold (usually under the name “papa lisa”) in modern packaging in supermarkets in Lima, Quito, Cali, and other big cities. Throughout the Andean region, it is considered a delicacy. It is one of the few native crops that is more widespread in the Andes now than it was 100 years ago; production is estimated to have doubled in just the past 20 years. In Peru in 1983, for example, more than 15,000 hectares were under cultivation; estimated production there is now more than 60,000 tons per year, and continues to increase. Around Cuzco, as well as in southern Colombia, ulluco is outranked only by oca, potatoes, and maize; near some urban areas, it is grown in almost every plot of suitable ground. 1 One of the bent types, splashed with maroon streaks, is known as “Christ's knee.” A small, pink, curled variety is called “shrimp of the earth.” A slightly curved yellow variety in Paucartambo is called “cradled baby.” The types with pink and magenta spots are sometimes called “pica de pulga” (flea bites) in Peru.

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Page 106 Ulluco is popular with Andean farmers because it has few pest and disease problems. However, even though the plant seems virtually disease free and its yields are considered high, recent studies in England indicate that it is probably invariably infected with viruses. Techniques for eliminating viruses (using meristem culture) have been developed, and disease-free clones may soon provide impressive increases in productivity. Preliminary observations indicate that virus-free plants show yield increases of 30–50 percent. With these vigorous, virus-free plants, ulluco yields comparable to those of potatoes can be expected. 2 Thus, it seems that removing viruses could transform this crop. 3 PROSPECTS The Andes. Ulluco has greater potential than most people realize. The availability of elite virus-free stocks could push it into the mainstream of commercial agriculture throughout the Andes. Because many diseases and pests are now appearing on the potato crop, potato production is becoming increasingly expensive. Ulluco is an excellent alternative for the small farmer. Ulluco seems particularly promising as a cash crop. Although most is grown for home use, some growers produce it mainly for the markets, and Ecuadorian farmers already consider it a prime cash crop Thus, dramatically improving yields could benefit both the diet and economic situation of the highland farmers. Other Developing Areas. This crop is now virtually unknown outside the Andes, but, like the potato, it seems to hold promise for temperate zones and tropical highlands. Resistant to frost as well as heat, ulluco grows vigorously and particularly thrives in moist conditions. It is high yielding in terms of tubers per plant, and is adapted to high altitudes. It could be grown in many upland regions of the tropics, and it has already fared well in Sri Lanka. 4 It also seems 2 An additional observation was that, under glass, the infected plants became dormant during winter, but the virus-free plants continued growing and, moreover, formed tubers more rapidly. 3 Information from O.M. Stone and A.A. Brunt. Field trials remain to provide conclusive evidence that these results will carry over to farm conditions. The most important virus, ullucus mosaic virus, is spread by aphids. Two others, ullucus mild mottle and papaya mosaic viruses, are probably spread mechanically. The fourth, ullucus virus C, is tranmitted by beetles. Regular distribution of clean planting stock is one solution to reinfection. 4 Information from J. Duke.

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Page 107 ~ enlarge ~ Chinchero, Peru. Although the potato has become the fourth largest crop of the world, ulluco and some of the other “unknown” tubers are equally popular in its homeland in the Andes. Here, potatoes (in bowl) and ulluco (in basket) are being prepared together for a stew. (N. Vietmeyer) promising for the uplands of Africa and China. All in all, the Andes has much to give the high-altitude regions of the tropics, and ulluco is a good example. Industrialized Regions. Ulluco will probably be popular wherever it becomes available. In Europe, North America and Japan, for example, it would be beautiful in supermarket displays, and could prove to be a profitable specialty crop. The tuber's small size could be a marketing asset—rather than a drawback, as with other roots. Because of the variety and brilliance of their colors, they could be sold as a mixed blend rather than as a uniform product. Despite this potential, ulluco may not be an easy crop to transplant to high latitudes. Most of the easily accessible types in Peru and Ecuador probably are limited by virus infections and daylength restrictions. Nonetheless, given concentrated research, ulluco could almost certainly be cultivated in high-latitude regions; researchers have already cultivated it in greenhouses at the latitudes of Vancouver, Canada (50° N), and Helsinki, Finland (60° N), as well as in open field conditions in England. 5 5 Information from T. Johns and A. Rousi, respectively.

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Page 108 Insular climates (such as in New Zealand or Hawaii) may lend themselves particularly well to ulluco. When days shorten as winter approaches, such places still have weeks of growing season left, during which time the tubers can form and swell. Continental summers, on the other hand, tend to end abruptly and may not leave enough short, cool days for the tuberization process to occur. In Hawaii, ulluco might thrive in the higher, cooler, moister elevations. USES Ulluco tubers have a wide range of culinary uses. Because of their high water content, they are most often boiled—sliced, shredded, grated, mashed, or whole—rather than baked. There is, however, some loss of color on boiling. The skin is about as thick as that on new potatoes, and is easily removed. Inside, the flesh is either white or yellow, and crisp like young potatoes, but slightly gummy until cooked. Ulluco tubers are also pickled or mixed with hot sauces. Generally, however, they are used to thicken soups and stews. For this they are preferred to potatoes, because they yield a smooth, silky soup rather than a grainy one. In urban households and restaurants in Ecuador they are frequently boiled and served cold as salad. The tubers have a good shelf life. They are stored for up to a year at ambient temperatures in the cooler areas of the Andes. 6 They must, however, be kept in the dark for their skins turn green in sunlight. Peru now exports canned ulluco to the United States, where it is often found in Hispanic markets. Unlike many vegetable products, the tubers retain their original taste and texture when canned; only a little color is lost. In the Andes, the tubers are sometimes freeze-dried (in the way potatoes are made into chuño) into a long-lasting product called “llingli.” This is usually ground into flour and added to cooked foods. The dried tubers have a much stronger taste than the fresh ones. The green leaves of ulluco are also nutritious. The plant is related to Malabar spinach (Basella rubra), which is widely eaten in the tropics as a potherb. In Colombia and Peru, the mucilaginous ulluco leaves are occasionally eaten in salads and as a vegetable. They are also sometimes boiled to make soup, or used like spinach, which they resemble in taste. 6 They have sprouted successfully after being stored two years in a refrigerator.

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Page 109 NUTRITION Ulluco is a good source of carbohydrate. Fresh tubers are about 85 percent moisture, 14 percent starches and sugars, and 1–2 percent protein. They are unusually high in vitamin C, containing 23 mg per 100 g fresh weight. They contain a gum, but no fat and almost no obvious fiber. 7 There is considerable nutritional variation, especially in protein content, which has been reported as high as 15 percent dry weight. 8 The leaves contain 12 percent protein dry weight. AGRONOMY The crop is normally propagated by planting small tubers. However, the plant is also easily propagated by stem cuttings or pieces of tuber (indeed, as long as they include a node, chopped-up pieces will root with weedlike robustness) without the help of hormones or other special treatment. The tubers sprout and grow readily when temperatures rise above about 18°C. Ulluco is grown much like oca, mashua, and potatoes. In fact, all four species are often planted together, with the tubers separated after harvest. As daylength shortens, stolons begin to grow out of the stem, and then tubers begin to develop on the ends of the stolons. This process can occur at any level on the stem, and ulluco is usually “earthed-up” to increase the number of stolons formed. Cultivars vary greatly in the time they require to reach maturity. The growing cycle may be as short as 5 months, but 6–8 months is more common; at high elevations (above 3,750 m) 9 months or more is the norm. Ulluco tubers are dug by hand. They resist bruising but, like new potatoes, they scar easily. Although fully mechanized harvesting has not been developed, it seems feasible. However, machines are likely to scuff the shiny coats, and in a crop whose appearance is of major importance, this could be a problem. Yields average 5–9 tons per hectare under traditional conditions. The largest tubers, from Colombia, may be fist size, but elsewhere they tend to be smaller than the size of an egg. Actually, it is the smallest tubers that are most sought after in the market. The tubers are stored almost year-round in the Andes. As noted, 7 On a dry-weight basis, 100 g of tubers may contain 364–381 calories, 10–16 g protein, 72–75 g total carbohydrate, 4–6 g fiber, 3–5 g ash, and 0.6–1.4 g fat. However, there is likely to be great variation between plants and growing sites. Information from S. King. 8 Information from S. King.

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Page 110 they are best stored in the dark. If exposed to the sun, the colors fade and eventually (because tubers are inherently stem material) they turn green. Most diseases that are known to attack ulluco seem to be specific to the plant. Andean farmers usually intercrop it with potatoes and there appears to be little or no interchange of diseases. LIMITATIONS Ulluco, as now produced, usually has lower yields than potato, but it seems unlikely that this would be a long-term limitation. Already, production sometimes reaches 10 or 15 tons per hectare, and at higher altitudes it can equal or surpass the potato yield. Give virus-free stock and improved growing conditions, low yield should no longer be a limitation. The tubers have a high water content and are not good for frying. They also shrink more than oca and potatoes during cooking. Because all ulluco appears to be tainted with viruses, strict cleansing and quarantine procedures must precede any introductions to new areas, thus limiting the availability and variability of germplasm in the short term. RESEARCH NEEDS Despite its importance to millions of people, little agronomic information concerning ulluco is readily available. Following are some of the research areas to be explored. Controlling Viruses Production and use of virus-free stocks and control of virus infections will probably lead to immediate, dramatic, and sustainable increases in production. This merits rapid and substantial research and operational effort. Removing Photoperiod Restrictions The plants are very sensitive to photoperiod. Cultivars need to be screened for their daylength requirements, and a survey made of their responses to different photoperiods. These variations will help indicate areas in which ulluco might be grown. Clones from the southern limits of ulluco's range should be evaluated for tuberization under longer daylength conditions and possible adaptation to temperate regions. 9 Inducing Seed Production In the past, it was thought that the plant never produced viable seed. However, researchers in Finland have 9 The plant occurs to 27°S latitude in northern Chile and northern Argentina.

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Page 111 obtained fertile seed under controlled circumstances. 10 This should greatly expand the potential for breeding and hybridizing; ulluco's genetic improvement should be speeded up as a result. In particular, true seed can be used to remove viruses and locate daylength-neutral types. Because viable seed would help with breeding and genetics, clones should be checked throughout the Andes and efforts made to develop fertile plants. In addition, the seed-producing capacity of wild relatives should be further assessed. Overcoming the sterility barrier would increase the variety of ulluco's colors and other variability to genetic manipulation. 11 Shortening the Cropping Cycle There is a need to find types for use in temperate latitudes that mature in a growing season of five months or less, yet are insensitive to daylength. Increasing Adaptability Clones should be screened for their relative characteristics by rotating them among different growing sites. Mechanization and Postharvest Handling Methods of mechanized cultivation and harvesting could prove useful. Selection for growth forms adaptable to mechanization is also desirable (sprawling types might not be acceptable, for instance). Methods of minimizing the scarring of tubers, loss of color, and for minimizing sprouting are also important. Ways to decrease harvesting, storage, and transportation problems could greatly increase the range of markets. Tuber Quality Consumer acceptability could be enhanced through selection of tubers that, when fresh, have reduced gumminess. Fertilizer Experiments The plant's fertilizer requirements are little studied, and it seems likely that substantial yield increases can be obtained in the Andes merely through the modest application of manure or fertilizer. SPECIES INFORMATION Botanical Name Ullucus tuberosus Caldas Family Basellaceae 10 Rousi et al., 1988. 11 Because there is much variation in spite of no known seed formation, there seems a good likelihood of frequent mutation in the vegetative tissues of ulluco. Researchers should keep a watchful eye for unusual tubers. Somaclonal variation selection is being carried out via tissue culture by R. Estrada in Peru.

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Page 112 Synonyms Ullucus tuberosus Loz., Ullucus kunthii Moq., Basella tuberosa HBK; Melloca tuberosa Lindl. and Melloca peruviana Lindl. 12 Common Names Quechua: ullucu Aymara: ulluma, ullucu Spanish: melloco (Ecuador), olluco, ulluco, rubas (Colombia, Ecuador); rubia, ruba, tiquiño, timbós, mucuchi, michuri, michiruí migurí (Venezuela); camarones de tierra, ruhuas, hubas, chuguas, chigua (Colombia); papa lisas, lisas, olluco, ulluco (Peru, Bolivia); olloco, ulluca, ulluma (Argentina); papa lisa (Peru, Spain) English: ulluco, melloco Origin. Ulluco is a completely domesticated crop. It is often represented in pre-Columbian art, and tubers have been found in 4,250-year-old ruins in coastal Peru—far from the area in which it currently grows. Wild forms (for instance, Ullucus tuberosus subsp. aborigineus Brücher) occur in Peru, Bolivia, and northern Argentina. They are mostly vinelike, with long internodes and reddish stems. Their spherical white, pink, or magenta tubers are about the size of small peas or marbles, and are more bitter than those of domesticated varieties. Description. Ulluco is a low-growing herb. All parts are succulent and mucilaginous. On long petioles from the angular stem are borne alternate, heart-shaped leaves, the color of which depends upon the cultivar. Wild forms are prostrate. Cultivated forms come in a gradient of types from prostrate or semiclimbing vines to dense, compact, bushlike mounds up to 50 cm tall. The small, green-yellow to reddish flowers are borne in clusters arising from the forks of the branches. Seed set has never been shown in either wild or cultivated forms in the Andes. 13 The plant forms tubers on long stolons both below and above the ground. Most arise below ground from the mass of fibrous roots, the ends of which thicken and swell. The tuber skin is thin and soft, with inconspicuous buds. Cultivated tubers can be elongated (2–15 cm) or curved. Some in southern Colombia are as big as normal potatoes. The most common are spherical and lemon yellow. However, coloration may be white, pink, orange, red, or magenta—a common, popular form has magenta spots speckled on a yellow background. Inside, the tubers are yellow or 12 Lindley recognized two species of ulluco, based on flower color and petal shape. 13 Viruses may contribute to their failure to set seed. As noted, researchers in Finland, using virus-free stock, have succeeded in getting ulluco seed. Information from A. Rousi.

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Page 113 white, with a clear distinction between skin and interior. They lack noticeable fibrous material. Horticultural Varieties. There is enormous variation in this crop: a single market may display six distinct types, and a market nearby may have six entirely different ones. Based on tuber appearance, some 50–70 distinct clones exist. 14 Some have been transported throughout the length of the Andes. Environmental Requirements Daylength. Daylengths of 10–13.5 hours are needed for tuber production in the varieties most commonly grown in the central Andes. However, some ulluco is grown in northern Argentina at 27°S latitude, and it seems likely that daylength-neutral types can be found in such places. 15 Rainfall. Moisture requirements are unknown, but probably are in the range of 800–1,400 mm during the growing season in the Andes. Altitude. Ulluco is an important mid- to high-altitude crop from Venezuela to Chile. 16 However, it has also been grown at sea level in Canada, England, and Finland. Low Temperature. The plant grows well in cool, moist conditions and is frost resistant. High Temperature. Although they thrive under high light intensities, ulluco plants produce tubers poorly in hot climates. Soil Type. This crop tolerates a wide range of soil conditions. Not unexpectedly, however, it does best in a fertile, well-drained loam with a pH between 5.5 and 6.5. 14 Information from C. Sperling. 15 This considerable variation may be an indication of ulluco's inherent diversity. 16 The uppermost elevation varies with latitude and location. Ecuadorian production is concentrated at elevations between 3,000 and 3,500 m; the highest report is of cropping at 3,700 m. In the Sierra Central of Peru, there are mixed crops of ulluco, oca, and bitter and nonbitter potatoes at about 4,000 m.