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Page 253 Highland Papayas The tropical papaya probably originated in the lowlands of Central America, but since the time of Columbus it has spread throughout the tropics and become well established. Languishing in the highlands of South America are several intriguing relatives that should be more widely cultivated. They, too, may have worldwide potential. These “highland papayas” 1 are particularly common in upland valleys of Ecuador and Colombia, but they can be found from Venezuela well into the southern cone countries. Like the common papaya, they are Carica species, but compared with their well-known tropical cousin, the highland papayas tend to be smaller, less succulent, and quite different in taste. The vast range of their diversity has not yet been collected or codified to any extent, and surprising discoveries quite likely await explorers, researchers, and entrepreneurs. These mountain papayas incorporate a wide array of flavors and qualities. Although some specimens are tasteless and many have to be cooked with sugar to make them palatable, a few specimens are highly appealing as fresh fruits—having mild, fresh, melonlike textures and flavors. Extremely fragrant, they add an alluring scent to meals or special occasions. The types used for cooking are appealing in their own way. They are commonly added to soups and stews, to which they lend rich, fruity flavors. Generally speaking, highland papaya plants resemble the tropical papaya plant in appearance and have similar cultivation requirements. All are “herbaceous trees.” All can have enormous yields: often within a year or two of planting, the palmlike trunks are stacked with 60 mature fruits; some can have as many as 200. The fruits look somewhat like papayas, and all contain the enzyme papain—at least when immature. There are four important potentials for these crops: Direct use. The types that produce tasty, high-quality fruits could 1 We have elected to use “highland papayas” as a collective name for these Andean species. They have an utterly confusing variety of local names, the same word often being applied to different fruits in different areas.

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Page 254 be propagated and commercialized. One, the babaco (see later), is already entering international trade. Creating new fruits. Highland papayas are fascinating “raw materials” from which new fruits can be created. Given their great variability and the fact that many are interfertile, the opportunities for generating new taste combinations are immense. Horticulturists in several South American countries, as well as in New Zealand, Australia, Taiwan, Singapore, Italy, and Israel, are now exploring such crosses. Extending the range of papaya cultivation. These Andean cousins come from subtropical areas with elevations up to 3,000 m. Their genetic endowment for cold resistance could be of great significance: adding a few degrees of cold adaptability could expand enormously the world's production of, and appreciation for, common papayas. 2 They might, for instance, result in papayas that are suited to subtropical regions (such as Southern California and the shores of the Mediterranean) where commercial papaya cultivation is now impossible. 3 Improving papaya production. The tropical papaya is plagued by pests. Genes from highland papayas have already been effectively employed in creating cultivars for regions where diseases (especially viruses) and pests (such as fruit flies) now restrict papaya cultivation, but more genetic benefits remain to be tapped. The following pages highlight six promising Andean highland papayas (four species and two hybrids). SPECIES4 Chamburo. From Panama to Chile and Argentina, the chamburo 5 (Carica pubescens 6 ) is commonly found around mountain villages. It 2 The highland species are difficult to cross with common papaya using traditional breeding techniques, but newer methods seem likely to make the process routinely successful. For example, tissue culture techniques to propagate plants from fertile but nonviable seeds add an important tool to the quest for new papaya combinations. Information from J. Martineau, R. Litz, and H.Y. Nakasone. 3 Highland papayas will not withstand heavy frost, but they yield under cooler climatic conditions than normal papaya plants. Their flowers and fruits are less affected by cool weather. Thus, they produce ripe fruit at cool temperatures where normal papaya fruits remain immature and insipid until they rot. 4 For the sake of simplicity, throughout the chapter we have used the scientific names of Badillo (1971) for species, and those of Heilborn (1921) for hybrids. Only the most common of the multitudinous synonyms are listed. 5 Other common names include chambur, chamburu, chambura, papaya de olor, papaya de montaña, papaya de altura, papaya de tierra fria, col de monte, papayuella, papayo, siglalón, chihaulcan, chiehuacan, bonete (Mexico), and mountain papaya or mountain pawpaw. Some of these names are also used for other highland papayas. In southern Ecuador as well as outside the Andes (notably New Zealand), the name “chamburo” commonly refers to Carica stipulata (see below). 6 Strictly speaking, the botanical name is Carica pubescens Lenné & Koch. Synonyms include C. cundinamarcensis and C. candamarcensis.

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Page 255 is by far the most common and widespread species of highland papaya. In eastern Peru it occurs in almost every backyard. In northern Chile it is grown commercially in plantations. The five-sided yellow fruits have firm flesh and a fragrance both pleasing and penetrating. They are 15–20 cm long, weigh about 130 g, and have a medium papain content. The interior cavity contains many spiky seeds. Fruits vary greatly in sweetness: some can be eaten fresh, but most must be cooked. They are suitable for stuffing with fruits, vegetables, or other fillings because their firm flesh holds its shape during cooking. They yield a clear juice and are excellent in pies, ice cream, marmalades, or sweets. Canned preserves are marketed in Chile. The plant is distinguished by the coating of hairs on the underside of the leaves. It grows in areas ranging from dry, windy, open plateaus to humid, shaded forests. It is found at altitudes up to 3,000 m, and withstands −3°C without serious injury. Most plants have flowers of a single sex (dioecious); a few have flowers of both sexes (monoecious). Chamburo is generally propagated by seeds. It grows vigorously and bears fruit in its second year. It is fairly tolerant of nematodes and is perhaps resistant to papaya ring spot virus, the most devastating disease of the common papaya. Siglalón. This species (Carica stipulata 7 ) is limited to a small region of southern Ecuador, 8 usually at elevations of 1,600–2,500 m. Again, there is much variability among individual plants. In comparison with common papayas, the fruits are quite small, and most are cooked with sugar and eaten as sweets. They are said to be the best highland papayas for jams and sauces. They are also boiled, strained, sweetened, and made into fruit drinks, normally in blends with other juices. Only a few plants yield fruits that can be eaten raw, but some of those are delicious. The yellow fruit has 10 or 11 ridges, weighs 40–150 g, and possesses a strong, pleasant aroma. The creamy flesh contains many seeds—some smooth, some corky. Many fruits are soft skinned and long; others are firm and squat. They are easier to peel than those of chamburo (C. pubescens), but the immature fruits have perhaps the highest papain content of any papaya and, even in ripe ones, the raw juice tends to irritate the skin, notably the corners of the mouth. The spiny, occasionally branched, tree is robust and grows vigorously 7 This species was first distinguished taxonomically only in 1966 as Carica stipulata Badillo. 8 In Azuay and Loja provinces, where it is native, it is also known as siglalón silvestre, paronchi, toronche, toronchi del campo, and chamburo, the name often used in popular literature.

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Page 256 its first year to as much as 2–3 m. (It may eventually reach 8 m.) Male and female flowers are borne on separate plants. Fruits develop in the second year, and some plants have borne fruits annually for more than 20 years. The seeds come fairly true, but vegetatively propagated plants bear fruit at an earlier age. It is possible that this (and some of the other highland species) might be grown as a source of papain. This enzyme is a valuable international commodity used, among other things, to clarify beer. Siglalón has fairly good resistance to papaya ring spot virus. Col de Monte. The col de monte 9 species (Carica monoica 10 ) is a “dwarf” papaya, most commonly found in cultivation in Ecuador and eastern Peru between 600–1,700 m elevation. There, the people like the fruit so much that they protect and nurture even wild specimens. The smooth, hard-skinned fruit has faint ridges and an orange, sometimes brilliant, skin. Typically, it has firm, orange or deep-yellow flesh with only a slight taste, large-horned seeds, and a high papain content. Some of these small, fragrant fruits are eaten raw—usually mixed with other fruits. Cooked with lemon and sugar they have been likened to stewed apricots. Their firmness makes them suitable for drying and candying, and they freeze well. The young seedlings and mature leaves are cooked as greens (hence the common name “col de monte,” which, translated, means “mountain cabbage”). The plant grows vigorously, but reaches only 1–3 m in height. It is found mostly in areas of high rainfall and mild temperatures. It is generally monoecious, commonly having male and female flowers together on the same inflorescence. The flowers are usually self-fertilized and the plant comes fairly true from seed. It crosses easily with C. pubescens, often yielding hybrids that bear much fruit of good flavor. It is susceptible to papaya ring spot virus. Papayuelo. 11 As with the other highland papayas, this small, hardy Colombian species (Carica goudotiana 12 ) is highly variable. Some of its fruits are quite sweet with an attractive taste somewhat like apples. Others are astringent and barely edible, even cooked. The fruits are usually five-angled, pale yellow, with occasional 9 Other common names include col de montaña, papaya de selva, tomate de monte, peladera, peladua, dwarf papaya, orange paw paw, and Peruvian cooking papaya. The name “col de monte” is often loosely used for any short-statured highland papaya. 10 One synonym is Carica boliviana. 11 Sometimes called “col de monte” or “payuello.” Both these common names are used in other areas for other highland papayas. 12 One synonym is Papaya gracilis.

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Page 257 shades of purple, red, or orange. They grow up to 20 cm long and weigh up to 200 g. The plant occurs in humid forests between 1,500–2,300 m elevation. It can, however, tolerate some dryness. It often branches at the base and has an upright habit with a gray trunk. Generally small, it can reach heights of 8 m. It is mostly dioecious (both male and female flowers are sometimes intensely red or purple, with red or green petioles), bears heavily, and its fruits transport well if harvested before full maturity. HYBRIDS Several of the more popular highland papayas are natural hybrids. Found most commonly in southern Ecuador, these present a great deal of variation in fruit size and quality. Some produce a few viable seeds whereas others produce no seeds at all. To maintain clonal uniformity, the plants are most often propagated vegetatively. Two of these hybrids are highlighted here. Babaco. The babaco 13 is the most commercially advanced highland papaya. Its fruits are fragrant and flavorful, with quite a different scent and taste from the common papaya. Its distinctive flavor has been likened to the taste of strawberry with a hint of pineapple. Sweet to some palates, it is pleasantly subacid—unique and refreshing. The large, normally seedless, “zeppelinlike” fruits, some weighing 2 kg, can be consumed fresh or stewed. When picked, the babaco (“ba-bah-co”) is green to yellow; when mature, it is bright yellow. The pulp is white to cream in color, juicy, and melting in consistency. The fruit is easy to prepare because it can be eaten skin and all, and there are no seeds to remove. Babacos are popular and common over a wide area of the cool highlands of Ecuador between elevations of 1,400 and 2,500 m. Most are found in small holdings, but some larger plantations have been established. Until recently it was unknown in neighboring countries, but plantings have now been started in Colombia. It is also being grown successfully in New Zealand, Australia, Israel, Italy, Guernsey, and California. It is probable that babaco could grow well in many other locations. 14 It is especially successful as a greenhouse crop because the plant is small and needs no pollinators. 13 In the terminology of Heilborn, who treated the plant as a species, this plant's botanic name is Carica pentagona Heilborn. The full binomial that indicates its hybrid status is Carica x heilbornii Badillo n.m. pentagona (Heilborn) pro species. It seems to be one of the possible crosses between Carica pubescens and Carica stipulata. 14 Kenya, Greece, and Brazil are reportedly starting commerical production.

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Page 258 ~ enlarge ~ Auckland, New Zealand, Babaco has a phenomenal capacity for high yield. Yields of 100 tons per hectare have been recorded merely a year or two after the trees were planted, Shown here are the fruits of just three babaco trees, (D., Endt)

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Page 259 Babaco has potential for export as a fresh fruit. New Zealand growers are already shipping it to Japan and the United States. When properly harvested and carefully packed, it remains in good condition for a month or more at 6°C. The cut fruit also keeps well and does not turn brown (oxidize) over time. Babaco is a small plant (1–2 m), only occasionally branched, but it coppices well. Total yields are better than those of a good papaya plantation, and have exceeded 100 ton per hectare. 15 Propagation is by cuttings or tissue culture. Toronchi. Toronchi 16 is a natural hybrid 17 found scattered around houses and villages in southern Ecuador. It is a frost-resistant, vigorous plant that may grow to 5 m, although most selected types are smaller, reaching only 2.5 m. It is found up to about 2,500 m elevation, and can withstand temperatures down to 1°C. There is much variation, but all specimens produce attractive, quality fruits with a delightful fragrance. They are eaten fresh or processed and are readily accepted, even by those tasting them for the first time. Cooked, they are useful for sauces, jams, pie fillings, and pickles, as well as for adding to cheesecake and dairy products such as yogurt. The mature fruit is five-sided, generally 10–15 cm long, green to lemon-yellow in color, and weighs up to 0.5 kg. It is extremely juicy with a soft, creamy-white pulp and is one of the least seedy of the highland papayas. Smooth skinned, it can be eaten without peeling, and has a medium papain content. A New Zealand variety called “Lemon Creme” is a vigorous cultivar that produces an abundant crop of sweet, lemon-scented fruits. Fast growing, these plants bear within 12 months. Picked ripe, the fresh, raw fruits are superior in flavor to all other highland papayas. However, they must be handled more delicately than the babaco; even when moderately ripe, they are poor shippers. Although the plant functions as a sterile hybrid, pollination seems to increase production, and the fruits often contain viable seeds. Toronchi hybridizes readily with siglalón (C. stipulata), resulting in many intermediate forms with different flavors and varying amounts of seed. PROSPECTS The Andes. All of these fruits are consumed locally throughout much of the Andean highlands, but currently only Colombia, Ecuador, 15 Information from F. Cossio. See also Cossio, 1988, p. 50. 16 Common names include toronche, toronche de Castilla, poronchi, chamburo, and chamburo de Castilla. 17 Carica chrysopetala Heilborn. This hybrid is now commonly known as Carica x heilbornii Badillo n.m chrysopetala (Heilborn) pro species.

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Page 260 ~ enlarge ~ Auckland, New Zealand. As with many little-known Andean fruits, innovative and courageous private researchers in New Zealand have pioneered the production and international export of babaco. Shown here on January 7, 1982, is part of the first-ever export shipment, ready for loading into the temperature-controlled cargo hold of a 747 aircraft bound for Frankfurt, West Germany. (D. Endt) Chile, and Venezuela are seriously exploiting their commercial potential. 18 These plants deserve much more horticultural attention. They could add appreciably to fresh-fruit production in the Andean highlands, and they are generally well suited to the smallholder. The benefits to child nutrition, family income, and general welfare are likely to be significant. Given adequate quality control, it might be possible to develop both a fresh-fruit export business and an Andean papain-extraction industry. (This enzyme is a low-volume, high-value item with export potential.) Because highland papayas are so variable and adaptable, it seems likely that types superior to those of today will be discovered or developed. With their great adaptability and high yield these “new” papayas—given genetic selection and improvement—should be a bonanza. 18 In Colonia Tovar, Venezuela (near Caracas), babaco production has become established since two scientists introduced cultivars 20 years ago.

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Page 261 Other Developing Areas. For cooler parts of the developing world, highland papayas could provide a range of future fruits. Indeed, with their extreme variability, they could become a veritable backyard fruit bazaar for upland villages from Morocco to Papua New Guinea. Like the common papaya in the lowlands, these Andean species and hybrids could provide masses of tasty, nutritious fruits in the highlands. It is likely they would enter local trade and, in time, develop into profitable small-scale or even large-scale domestic and export operations. Before their commercial value can be exploited, however, there is a need to select and develop types that have good and uniform qualities and that can be propagated on a large scale. Industrialized Regions. Highland papayas may be potential fruits for subtropical and warm-temperate areas of North America, Europe, Japan, and Australasia. However, they require climates that are free from both frosts and excessive summer heat. These plants can be susceptible to certain pests and diseases, particularly to nematodes, mites, root rot, and viruses. Their climatic requirements and cultural practices for maximum production and best flavor are little known. Thus, considerable horticultural attention is needed before they can be exploited with confidence. Postharvest handling studies would greatly increase their market potential. Although the fragrance of many of these fruits is instantly appealing, the taste is unusual, often must be acquired, and can be disappointing to consumers expecting a papayalike flavor. Although for simplicity we have called these “highland papayas,” an important strategy in the wider marketing of these species is to create or adopt new names that avoid the papaya image and that allow the fruits to be judged on their own merits. To create cold-tolerant papayas has been the plant breeder's goal for almost a century. With modern technology, better germplasm collections of Andean species, and old-fashioned persistence, it seems probable that this goal can be achieved.