|Plate LXIV: COCONA, Solanum sessiliflorum|
The cocona plant is a much-branched, herbaceous shrub 6 1/2 ft (2 m) high, with downy stem, densely white-hairy twigs, and ovate leaves, oblique at the base, scalloped on the margins, downy on the upper surface, prominently veined beneath; 18 in (45 cm) long and 15 in (38 cm) wide. New shoots are rusty-hairy on the underside. The wild variety georgicum has spines on stem, branches and leaves. The flowers, in clusters of 2 or more in the leaf axils, are 1 in (2.5 cm) wide, with 5 pale greenish-yellow petals, 5 yellow stamens, and a dark-green, 5-pointed calyx. Borne singly or in compact clusters on very short peduncles, and capped with the persistent calyx, the fruit may be round, oblate, oblong or conical-oval, with bluntly rounded apex; 1 in (2.5 cm) to 4 in (10 cm) long, and up to 2 1/3 in (6 cm) wide at the base. The thin, tough skin is coated with a slightly prickly, peach-like fuzz until the fruit is fully ripe, then it is smooth, golden- to orange-yellow, burnt-orange, red, red-brown or deep purple-red, and has a bitter taste. Within is a 1/4 to 3/8 in (6-10 mm) layer of cream-colored, firm flesh enclosing the yellow, jelly-like central pulp. The cut-open fruit has a faint, tomato-like aroma. The flesh has a mild flavor faintly suggestive of tomato, while the pulp has a pleasant, lime-like acidity. Abundant throughout the central pulp are the thin, flat, oval, cream-colored seeds, 3/32 to 3/16 in (2-4 mm) in length and unnoticeable in eating.
Origin and Distribution
The spineless cocona is apparently unknown in the wild, having been observed by botanists only in cultivation from Peru and Colombia to Venezuela and bordering regions of Brazil. In 1760, a Spanish surveyor, Apolinar Diez de la Fuente, found the cocona with maize and beans in an Indian garden between Guaharibos Falls and the juncture of the Casiquiare and Orinoco rivers. In 1800, Humboldt and Bonpland, traveling up the Orinoco, observed that the cocona was one of the common plants in the region between the Javita and Pimichin rivers, and they collected specimens on which the first technical description was based. In the mid-1940's, seeds from the upper Amazon were planted at the Experiment Station in Tingo Maria, Peru, and, later on, the plant was grown at the Instituto Interamericano de Agricultura at Turrialba, Costa Rica. Seeds sent from Natal, South Africa, were planted at the University of Florida's Agricultural Research and Education Center, Homestead, Florida, in 1948. By 1950, all the resulting plants had succumbed to nematode damage. The seeds sent to Medellin, Colombia, in 1948 could have been from these plants. Dr. J.J. Ochse grew specimens in a plot outside the then Botany Building at the University of Miami, Coral Gables, Florida, in 1953.
Dr. Niilo Virkki of Cupey, Puerto Rico, bought one fruit from a street vendor in Manaus, Brazil, in June 1964 and planted the seeds when he returned home. The seedlings grew vigorously and began fruiting in March 1965. Plant breeders studied the plant and fruits in view of its possible potential for hybridizing with the naranjilla. They determined the chromosome number of the cocona to be 2n = 24.
The fruits are much eaten by the Indians and commonly marketed throughout the producing areas of Latin America. In Colombia and Brazil, the cocona is a domestic product, in Peru it is the basis of an industry. Cultivation is being encouraged by Gerber's Baby Foods and farmers are guaranteed a good price. Canned juice is being exported to Europe.
The wild variety, S. topiro var. georgicum Heiser, of the lowlands of eastern Ecuador and Colombia, is a smaller plant with smaller fruits and with spines on the stem, branches and leaves. It spontaneously hybridizes with the typical var. topiro, and Dr. Charles Heiser of Indiana University views it as the ancestor of the cultivated cocona.
In Peru, 4 types are distinguished: a) small, purple-red; b) medium, yellow; c) round, resembling an apple, yellow; d) pear-shaped. The medium-sized cocona is in greatest demand in Peru and especially for juice.
The Divisão de Ciencias Agronomicas of INPA in Amazonia, made a collection of 35 strains of cocona from Belem do Pará, Brazil, and Iquitos, Peru, and established an experimental block of 149 plants in pure sand for evaluation. The range of variation indicated that seedling coconas represent a great reservoir of characters to be utilized in improvement of the crop, to enhance nematode resistance, reduce seed count, and increase sweetness.
In Florida and Trinidad, the cocona is grown at near sea-level. In Colombia, it is grown from sea-level to an elevation of 2,000 ft (610 m), while elsewhere in South America it thrives at altitudes up to 3,000 or 4,000 ft (910-1,200 m). Unlike the naranjilla, the plant needs full sun.
The cocona grows in soil of medium fertility on Peruvian mountain slopes; in Amazonian Brazil, on latisols or pure sand. In Puerto Rico, it has done well on clay; in southern Florida on scarified limestone. Good drainage is essential.
The cocona is self-fertile. Bees are always visiting the flowers and carrying pollen, and natural crosses are common. Fruits mature about 8 weeks after pollination.
There are from 800 to 2,000 seeds in each fruit. New plants spring up voluntarily from seeds clinging to discarded rinds in full sun on disturbed ground in northern South America. For planting, seeds extracted from the ripe fruits are placed in the shade for 2 days to ferment a little and break down the mucilage. Then they are washed and dried briefly out of the direct sun, and finally dusted with fungicide 2 1/4 g per lb (5 g per kg) of seeds. The seeds are planted 3/8 in (1 cm) deep in nursery beds in rows 8 in (20 cm) apart; or in polyethylene bags containing a 50-50 mixture of potting soil and sand. In each bag, or each hole, one puts 4 to 5 seeds expecting the emergence of 1 or 2 sturdy seedlings. Germination time varies from 15 to 40 days.
Vegetative propagation is possible, in order to perpetuate a particular cultivar. Air-layers and cuttings of mature wood have been rooted successfully.
Seedlings are transplanted to the field when 8 to 12 in (20-30 cm) high and they are spaced 5 to 7 ft (1.5-2.5 m) apart each way, depending on the fertility of the soil. Flowering commences 2 to 3 months after transplanting. The plants usually begin fruiting in 6 to 7 months from seed and will continue fruiting for several months.
A fertilizer formula of 10-8-10 NPK is applied 6 times during the year at the rate of 1.8 to 2.5 oz (50-70 g) per plant. If the soil is low in phosphorus, the formula should be 10-20-10. Productivity has been greatly enhanced in field trials at Manaus on pure sand, by applying organic fertilizer104 tons per acre (250 tons/ha), with the addition of appropriate amounts of triple super-phosphate, urea and chlorate of potassium.
Average annual yield in Colombia is 22 to 44 lbs (10-20 kg) per plant. In Costa Rica, cocona plants have yielded 40 to 60 lbs (18-27 kg) of fruit. In variety trials at Manaus, productivity per plant varied from 5 1/2 to 30 lbs (2.5-14 kg). An unfertilized plantation may provide 20 to 30 fruits per plant12 tons per acre (29 tons/ha). With a high-yielding selection and a well-fertilized field, one can realize up to 136 fruits per plant61 tons per acre (146 tons/ha). The fresh fruit keeps well for 5 to 10 days at normal temperature.
Processing studies have shown that 22 lbs (10 kg) of fruit will yield about 6 1/2 pints (3 liters) of preserved flesh and 3 1/4 lbs (1 1/2 liters) of jelly, or 2 gallons (7 1/2 liters) of juice. A plantation providing 30 tons fruit per acre (70 tons/ha) will yield 5,548 gallons preserved flesh and 2,774 gallons of jelly, or 13,738 gallons (52,000 liters) of juice.
Pests and Diseases
The cocona is prone to attack by rootknot nematodes (Meloidogyne sp.). In 1973, it was decided, after test plantings at the Universidad Central de Venezuela, that it was impossible to cultivate the cocona commercially in that country because of its susceptibility to nematodes, but the experimenters at Manaus believe that they have demonstrated that selection for nematode-resistance and soil-enrichment can give the farmer good returns.
In Puerto Rico, a mealybug, Pseudococcus sp., infests the new growth but causes little harm. However, Psara periosalis has been very damaging in the fall. Cutworms and leaf-eating insects require control. In Brazil, a hemipterous bug of the family Tingidae colonizes the underside of the leaves, causing them to discolor and fall. A fungal disease (Sclerotium sp.) has been identified with wilting.
The ripe fruit is peeled and eaten out-of-hand by South American Indians. More sophisticated people use the fruit in salads, cook it with fish and also in meat stews. Sweetened, it is used to make sauce and pie-filling. It is prized for making jam, marmalade, paste, and jelly, and is sometimes pickled or candied. It is often processed as a nectar or juice which, sweetened with sugar, is a popular cold beverage. Dr. Victor Patiño of Cali, Colombia, states that a 50-50 cocona-naranjilla juice mixture is superior to naranjilla alone.
In Brazil, the leaves are cooked and eaten as well.
|Food Value Per 100 g of Edible Portion*|
*Analyses made in Brazil.
The fruit has a high level of citric acid, about 0.8%. Venezuelan studies reveal 142 mg tannin.
The cocona is utilized by Indians of eastern Peru to rid the head of lice.