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Page 93 Potatoes During the approximately 8,000 years that potatoes have been cultivated in the Andes, farmers have selected types to meet their particular local needs and preferences, as well as to thrive in the myriad microenvironments scattered throughout South America's 4,000-km-long mountainous backbone. This vast and long-standing selection process has resulted in thousands of distinct types, and Andean Indians sometimes grow up to 200 different kinds of potatoes in a single field. Most of these Andean potatoes (various Solanum species) are quite unlike what people elsewhere take to be “normal” for a potato. They can have skin and flesh that is often brilliantly colored (sometimes bright yellow or deep purple). Some have eye-catching shapes, often being long, thin, and wrinkled. And most have a rich potato flavor and a high nutritional quality. These “odd” potatoes deserve much more recognition. Many have appealing culinary qualities and could fill specialty niches in the huge worldwide potato industry. For example, they can be less watery than common potatoes or have nutlike tastes and crisp textures. Moreover, most of these little-known potatoes are adapted to marginal growing environments and possess considerable resistance to various troublesome diseases, insects, and nematodes, as well as frost. There has never been a better time to investigate these lesser-known crops. New markets for small or unusual potatoes are springing up. In North America, for instance, the food industry is avidly exploiting miniature vegetables of all kinds, and demand is increasing for small and colorful potatoes in particular. 1 , 2 1 In 1986, for example, the state of Maine sold almost 400,000 kg of potatoes, ranging in size from golf balls to billiard balls. The wholesale price was about one-third higher than for normal-sized potatoes. Sold as gourmet delights, these “Baby Maines” are packaged in designer boxes. Sales have climbed each year since the program began in 1983. 2 An entrepreneur in California has had remarkable success selling golden and purple-colored potatoes as premium specialty vegetables from coast to coast. Her marketing is based solely on their color.
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Page 94 In addition, it is important that these potatoes be assessed and used because most of these species are becoming rare in the Andes—phased out in favor of modern varieties, which have undergone vastly more agronomic development. Indeed, some are so close to extinction that it is vital to focus scientific attention on them before they are lost. However, it should not be assumed that all one needs to do is to gather these Andean potatoes and distribute them to the world. On the contrary, they have grave limitations. Many are grown only on high mountain slopes and may be restricted to such environments. Most seem to be less vigorous and to yield fewer and smaller tubers than modern commercial potatoes, especially when grown under commercial conditions. Most have deep eyes and irregular shapes that make them harder to process and handle in bulk than regular potatoes. Also, many, if not most, have strict daylength requirements and currently yield poorly in temperate zones because they need short days to induce tuberization. Despite some apparent geographic and daylength limitations, these potatoes have potential for commercial success; the technical constraints to their wider adoption seem likely to be overcome through diligence, conventional breeding and tissue-culture techniques, and the improved disease-indexing techniques now available. They could perhaps usher in a new era in potato cultivation. Even the low yield may not be inherent. Under the marginal conditions where they now grow, many of these native potatoes are not reaching their potential because of soil infertility, inadequate moisture, poor management, soil nematodes, viruses, and the poor quality of “seed” available. 3 SPECIES Many of the little-known potatoes of the Andes belong to different species from the common potato elsewhere, but one is its ancestral form. This one and seven others are described below. 4 Pitiquiña. Widely considered the most primitive of the domesticated potatoes, this species (Solanum stenotomum 5 ) produces tubers that are long; cylindrical; knobbly; red, black, or white; and small 3 Information from J.S. Niederhauser, who reports that in the highlands of Bolivia, andigena varieties (see later) have yielded the equivalent of 15–20 tons per hectare when there was a source of good seed, plenty of fertilizer, and control of nematodes, insects, and weeds. 4 The scientific names used in this chapter are for identification purposes only. The taxonomy of the potato is complicated in the extreme. No endorsement of one set of claims over another is intended or implied.
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Page 95 ~ enlarge ~ Selling limeña potatoes on the streets of Lima. In the homeland of the potato, where there are literally hundreds of types to choose from, limeña potatoes are among the most popular because of their flavor. The larger, more watery types that are best known elsewhere are among the least popular. (Z. Huamán) with deep eyes. Some are spiral in shape. They have a good, nutty flavor and unusually high amounts of protein and vitamin C. This diploid (see page 102) is grown intermixed with common potatoes in traditional fields. Bolivian farmers, for instance, often plant a few rows of “collyu papa,” a pitiquiña (pronounced pee-tee-keen-ya) variety, for their own consumption, and andigena varieties (see below) for the market. The plant is becoming rare and is not now grown outside the Andes. Some strains are fairly frost resistant. It produces fertile seed. The tubers require a dormant period before they will sprout. Typically, they are stored 4-5 months between crops. Limeña. Known in the Andes as limeña (pronounced lie-main-ya) or papa amarilla (“yellow potato”), this species (Solanum goniocalyx) produces a potato with deep-yellow flesh of exceptional flavor. It is fried and sold as a culinary specialty in the streets of Lima, Peru, for 5 Thought to be the original progenitor, from which all other cultivated potatoes sprang. It is extremely close to such wild species as Solanum leptophyes and S. canasense, which are Andean weeds commonly found in vacant fields and along roadsides. It may have arisen from them by selection.
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Page 96 ~ enlarge ~ The potatoes of the Andes come in a variety of shapes, colors, sizes, and flavors. Shown on these pages are the little-known potatoes highlighted in this chapter. All are different species from the potato used in the rest of the world, except for the andigena potato, which is a different subspecies. (Z. Huamán) instance. Most varieties have white flowers and yellow tubers (both flesh and skin) that are the basis of a tasty yellow soup that is a traditional Peruvian food and an important part of the noon meal in many Andean countries. The plant is a diploid and is closely related to pitiquiña, of which it may be just a variant or subspecies. It is still widely grown in temperate-climate areas of the Andes because people are willing to pay a premium for its quality and taste. It is unknown outside the Andes. It produces fertile seed. Phureja. The phureja (pronounced foo-ray-ha) potatoes (Solanum phureja) 6 are also small, irregular, and tasty. They are grown mainly at lower altitudes (2,200–2,600 m) on the warm, moist eastern slopes of the Andes from Venezuela to northern Argentina. Some yellow-fleshed types are fried and sold in city streets (for example, in Bogotá where they are called “papa criolla”) and in the markets of La Paz, Bolivia. Although rarely seen outside the Andes, the phureja potato 6 For simplicity, we refer to it as a separate species, but some scientists consider it a subspecies, a variety, or a cultivated group of Solanum tuberosum.
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Page 97 ~ enlarge ~ has become popular in the Netherlands, because of its resistance to disease. The plants exhibit good heat tolerance, and their genes have been incorporated into the two most heat-tolerant varieties of the common potato. But phureja tubers lack dormancy: most of them are already sprouting when they are harvested. 7 This is a useful trait for growers who expect two or three crops a year, but it causes problems in storage and handling of the commercial harvest. This diploid plant probably arose from Solanum stenotomum when ancient peoples selected it for its short dormancy. At least 500 named varieties are known. Most are deep-eyed and highly pigmented (often purple), with spindly, twisted shapes. In the Andes, they are mostly boiled, but they can be baked or fried. They are high in protein and vitamin C and have a stronger flavor and a firmer texture than the common potato. Andigena. This is the potato 8 immediately ancestral to the potato of commerce. To most botanists the two are the same species, but to nonspecialists they look vastly different. In Latin America, this is not 7 Normal potatoes must remain dormant for 2–3 months at room temperature or 4–5 months refrigerated before they will sprout. 8 Some designate this as a species in its own right (Solanum andigenum); others classify it as a subspecies, or a horticultural variant of S. tuberosum.
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Page 98 a “lost” crop: from northern Argentina to Venezuela, as well as on mountainsides in Central America and the Mexican cordillera, it is perhaps the best-known potato. However, there is little or no commercial cultivation of it anywhere else. 9 Of all the traditional potatoes of the Andes, andigena (usually pronounced an-di-je-na in English) potatoes produce the largest tubers. They are rounder, shallower eyed, and more uniform in shape than those of the other neglected species. They come in a range of pigments from yellow to black. They are firm and nutritious: protein levels up to 12 percent on a dry-weight basis have been recorded, which is higher than that of modern commercial varieties (about 8–10 percent). 10 Like all potatoes, they are high in vitamin C. This overall superiority in culinary properties and nutritional values, however, is offset by susceptibility to late blight. Although yields are often low, there are varieties yielding up to 30 tons per hectare. 11 Of all Andean potatoes, this species shows the greatest diversity, with 2,500 distinct native varieties. It is a tetraploid, believed to have sprung from Solanum stenotomum through chromosome doubling or by hybridization with another wild species, Solanum sparsipilum. It produces fertile seed. Chaucha. A hybrid between the two cultivated species pitiquiña and andigena (Solanum stenotomum and Solanum andigenum), the chaucha 12 potato (Solanum x chaucha) is widely distributed from Colombia to northwestern Argentina. It is an early-sprouting potato that needs no rest period. As it is a sterile triploid, the plant produces no seed; propagation is exclusively vegetative. New genotypes are produced only occasionally as a result of natural mutation in the field. The huayro, one of the major commercial potatoes of the Indian populace, is a chaucha potato. At least in Peru, this species has spread from the central highlands to almost the entire country and has much potential. Its tubers tend to be larger than those of many native potatoes, possibly because of hybrid vigor. Ajanhuiri. This highly frost-resistant potato (Solanum ajanhuiri) is extensively cultivated at altitudes of 3,800–4,100 m in the Andean Altiplano of the Lake Titicaca basin. This area is an inhospitable windy 9 Spaniards introduced the andigena potato to Europe at least as early as 1570. Although no longer grown in Europe, it is believed to be the ancestor of the modern potato. The actual sequence of events is a matter of debate and conjecture. Some researchers believe that modern potatoes are direct descendants of Solanum tuberosum gathered in Chile in the 1500s. This is now disputed by most authorities. 10 Protein percentage is a function of tuber size, which has to be taken into account. 11 Information from J.S. Niederhauser. 12 Pronounced chow-cha. The word means “early.”
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Page 99 plateau located in southern Peru and northwestern Bolivia. Frost severely limits agriculture there, restricting the choice of crops to this potato and a handful of other plant species. Some evidence shows that ajanhuiri (pronounced a-han-hwee-ri) was crucial to the survival of the Aymara Indians who live in the area. Subsistence farmers still grow it in small plots as an “insurance” crop, in case the andigena potato crop should fail owing to unpredictable heavy frost. The tubers have high contents of dry matter and vitamin C, and they store well. Only one clone, called “sisu” (pronounced see-soo), can be eaten without preparation. It is sweet, floury, and tasty. Its two main varieties are azul (blue tubers) and jancko (white tubers). The other clones are bitter and are made into chuño (see below). This species matures early and withstands temperatures as low as −5°C, as well as hail and drought. It is also resistant to viral diseases and round-cyst nematode, and is immune to Synchytrium black wart as well. Daylength requirements may reduce its usefulness for high latitudes, but if this restriction can be overcome, ajanhuiri is a potato with great international promise. Although known to taxonomists and plant breeders for some 50 years, it has not yet been widely utilized in potato breeding. This species is a diploid. It rarely produces fertile seed, and even then only in small amounts. Rucki. The rucki (pronounced rue-kee) is perhaps the most frost resistant of all potatoes. Actually, the name covers two species (Solanum x juzepczukii 13 and Solanum x curtilobum), which are grown in central to southern Peru and in northern Bolivia at altitudes up to 4,200 m. At this rarefied height they are often subjected to heavy frosts, even during the growing season. Both plants are hybrids between a cultivated and a wild species. (Such crosses occur along the margins of farmers' fields, which probably explains how they arose.) Both contain genes from Solanum acaule, a tiny wild species found at altitudes so high that in some cases it grows along the edges of permanent snowbanks. The cultivation of these plants long predates the Inca period, and although it continues to the present, farmers generally obtain low yields because neither plant has been subject to agronomic improvement. The farmers grow them as “security” crops because in the altiplano frosts can occur during 300 days of the year. Tubers from both plants are usually bitter, and can be eaten only after processing. They are used mainly to produce chuño, a freeze- 13 Pronounced jo-sep-soo-kee (English) or yu-sep-chu-kee (Spanish).
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Page 100 dried food that is bland, not bitter. This dry, white product can be stored almost indefinitely and is widely used in soups and stews. Solanum x juzepczukii is a triploid and gives no seed; Solanum x curtilobum is a pentaploid and produces fertile seed. Solanum hygrothermicum. This potato 14 is cultivated by Indians of the warm and humid lowlands of Peru's Amazon basin region. 15 It is the only potato traditionally grown under the climatic regime of a warm rainforest (2,000–3,000 mm of rain a year). It may be of value both as a hot-climate potato or for breeding purposes to impart heat tolerance. It has shown resistance, for instance, to bacterial wilt or “potato black-leg.” Unfortunately, it is so rare that it is close to extinction, and in fact may already be extinct. At present, there are no living collections, but the plant probably can still be found in the jungles of the Amazon basin. Explorations should be undertaken. PROSPECTS Andean Region. In the Andes, there exists enormous potential for the improvement and economic exploitation of these various, flavorful species. They usually sell for much higher prices than the common potato and continue to be widely (even if sparsely) grown. They are important as a buffer against the variability and unpredictability of environmental conditions. For some of the world's poorest populations, they increase farming options and reduce the risk of disastrous crop failure, especially that caused by frost. Given increased research attention, it seems probable that these lesser-known potatoes will be greatly improved and will find farmers eager to grow them. Yields can probably be increased merely by use of virus-free seed, for instance. Tissue culture propagation and the use of true (botanical) seed are also promising new technologies for developing inexpensive, virus-free plants. These species are important also for genetically changing the major cultivated potatoes. Their exceptional variability provides a rich source of genetic traits for incorporation into commercial potato cultivars. The cold tolerance of some species is of extreme importance. Also, there are potential nutritional advantages. Increased screening of native varieties should be seen as comple- 14 Information on this species from C. Ochoa. 15 For example, the Campas and Aguarunas in the central Amazon basin and the Machigangas in southeastern Peru.
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Page 101 THE PROMISE OF UNDOMESTICATED POTATOES ~ enlarge ~ In this report we have not described wild potatoes—of which there are several hundred species in the Andes. But this is not to suggest that the wild species lack utility. Indeed, some of them have unusual genetic qualities. A few, for instance, are virtually immune to the most formidable pests in potato farmers' fields. British agronomist R.W. Gibson has found two species of Bolivian wild potato whose leaves are veritable minefields to insects. Even a tiny aphid—one of the potato's major enemies—crawling over the surface breaks open minute, four-lobed hairs that cover the leaves. This releases a sticky material that clings so firmly that the aphid's legs become glued to the leaf and it dies. The glue will also catch the Colorado potato beetle, potato leafhoppers, and both tarsonemid and tetranychid mites. These particular wild potatoes are unsuitable as food crops, but already researchers are beginning to breed them with the common potato to give it glandular hairs with which to ensnare its insect enemies. The photomicrograph reveals an aphid that has become stuck to the leaf of Solanum berthaultii. (Rothamsted Experimental Station)
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Page 102 mentary to the ongoing effort to breed new varieties. For a subsistence farmer, reduction of risk overrides all other factors. If a crop is dependable, he will probably prefer it to something that has a high yield only in “good” years. 16 Other Developing Areas. In recent decades, the common potato has become a glowing success in the highlands of Central Africa and the Himalayan region. The Andean experience suggests that, with research, certain native varieties can compete successfully with the common potato. Thus, in time, these little-known potatoes could also be good contributors to the welfare of Africans and Asians. There could well be localized environments where even now the lesser-known species may prove superior to common potatoes. The heat-tolerant Solanum hygrothermicum, for instance, is native to a climate that is almost inimical to most varieties of the common potato. Also, some of the extremely cold-tolerant species may find valuable niches high on African or Asian mountainsides where few other crops can survive. Expanded research to evaluate such possibilities could open new vistas. As noted, some of the species are valuable sources of germplasm for enhancing the common potato's culinary quality, productivity, and resistance to pests, disease, and harsh environments. Industrialized Regions. In the United States, specialty vegetables are becoming a driving force in the multibillion dollar produce industry, and commercial interest in unusual potatoes is rising. Golden and purple potatoes are already selling at premium prices, and demand for more striking variants is probably endless. All the lesser-known potatoes should be intensively investigated and the adaptable cultivars promoted. A few cultivars of pitiquiña and phureja potatoes are currently being grown in Western Europe and North America. In North America, andigena potatoes would appear to be ideally suited to the specialty market. 17 In the Andes, most of these species are cultivated at fairly high altitudes, so the cool autumn weather of high latitudes (in Europe, North America, or Australasia, for instance) may pose little problem. However, the long daylength of summer poses a giant problem. The Andean potatoes come largely from equatorial latitudes and tuberize 16 It has been said that a new high-yielding, frost-resistant potato cultivar could do more for the political and economic stability of Bolivia than any other single factor. 17 One interesting marketing strategy would be to maintain the diversity inherent in these species and raise them as multicolored and multishaped populations. Baskets of rainbow-colored potatoes would be a trendy produce-marketer's delight.
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Page 103 HOW THE MODERN POTATO DEVELOPED The potato that reached Europe in the late 1500s was the andigena (page 97). But how it became the modern potato is a matter of debate. When grown in Europe today, andigena's stolons are very slow to swell to form tubers, and it produces little or no yield. Differences in daylength between the short days of the central Andes and the long days of a northern European summer are the cause. It is probably accidental that the andigena was transformed into a useful crop for Europe. In the 1600s and 1700s, some people propagated potatoes by planting botanical seeds. The resulting seedlings were highly variable; virtually every plant differed from all the others. This allowed a vast number of genes to be combined and expressed, and among the types that arose were some that could tuberize during long days. This is the explanation believed by most potato geneticists. There is, however, a possible alternative: that an unrecorded ship introduced “long-day potatoes” from southern Chile. Chilean potatoes are almost certainly also derived from andigena, but for centuries they have been adapted to long-day production. Whichever method transformed andigena, it was one of the most valuable genetic developments of all time; it gave the world what is now its fourth largest food crop: the modern potato. only under short day conditions. Such restrictive daylength requirements have been overcome in other crops by selection and undoubtedly could be done again. Appropriate varieties usually appear when large numbers of plants are grown under long-day conditions—only the few adaptable ones produce a crop. Also, long-day types are most likely to be found in the southern limits of the range of each species in the Andes. 18 The use of true seed to bring out daylength variability seems highly promising. The bitter potatoes are unlikely to create much interest outside the Andes, where chuño would be hard to make under natural conditions. As with other new produce (kiwifruit, for example), catchy names could be the key to consumer acceptance. For lesser-known potatoes, market-oriented names might, for instance, play up the brilliant colors, firm texture, bizarre shapes, or nutritive quality. 19 18 The Chilean regions of Temuco and Chiloe seem likely to produce daylength-neutral types. 19 Reviewers of this chapter came up with the following provocative suggestions: rainbow, gemstone, jewel, hotdog, spiral, golden-delicious, corkscrew, early bird, or brillante potatoes.
Representative terms from entire chapter: