|Fig. 116: The Mexican husk tomato, (Physalis ixocarpa), page-green, yellow, purple or reddish when ripe, is a staple food in Mexico and Guatemala and commonly marketed.|
The plant, which is a semi-woody annual, may attain a height of 4 to 5 ft (1.2-1.5 m), but is often prostrate and spreading. Its branches and leaves are smooth, not downy. The leaves are ovate, pointed at apex, wedge-shaped at base, sometimes wavy-margined; 2 1/2 in (6.25 cm) long, 1 1/4 in (3.2 cm) wide. Borne singly in the leaf axils, the flowers, clasped halfway by a 5-toothed, green calyx, are 1/2 to 3/4 in (1.25-2 cm) long and wide; yellow with dark-brown spots in the throat. As the fruit develops, the calyx enlarges to more or less enclose it and finally becomes straw-colored and papery. It is so tight-fitting that it often bursts. The berry is slightly oblate, 1 to 2 1/2 in (2.5-6.25 cm) wide. When ripe, its thin skin may be yellow, purple, or, more rarely reddish, or still green. The flesh is pale-yellow, crisp or soft, and acid, subacid, sweet, or insipid, and contains many tiny seeds.
Origin and Distribution
The Mexican husk tomato was a prominent staple in Aztec and Mayan economy. The plant abounds in Mexico and the highlands of Guatemala and the fruits are commonly seen in native markets. Nevertheless, this species has not been as widely distributed abroad as the Cape gooseberry. It was introduced into India in the 1950's and is cultivated in the northwest desert region of Rajasthan. In Queensland, Australia, and in South Africa it has fruited prolifically. There is some commercial cultivation in Pietersburg, South Africa, for processing. It was too-successfully introduced into East Africa, for, in 1967, it was reported to be the most important weed of agricultural fields in the highlands of Kenya.
Before 1863, it was thoroughly naturalized and commonly growing in abundance in the far west of the United States. Mr. Sun Jue cultivated some 20 acres (8 ha) of Mexican husk tomatoes near Los Angeles, California, from 1930 to about 1939, supplying the fruits to Mexican and Italian markets. In 1945, the American Fruit Grower publicized this species under the concocted name "Jamberry", as a new fruit introduced by scientists at Iowa State College. Dr. I.E. Melhus, Director of the Iowa State College Guatemala Tropical Research Center reported in 1953 that, as a result of 6 years' testing of hundreds of selections, only a few were found suitable for the American Midwest. They were then sending out a strain to which they had given the name "Mayan husk tomato"; 4,000 packets of seed were distributed in Iowa and adjoining states. Sampling data from 200 people that grew the plant showed that over 60% were successful and liked the fruit. Later, that strain was offered by the Earl May Seed Company of Shenandoah, Iowa. An apparently independent introduction was made by Glecklers, Seedsmen, of Metamora, Ohio, and first offered by them as "Jumbo husk tomato" in 1952. Seeds obtained from these sources and from fruits purchased in the Mexican markets were given by the writer to experimenters in the Bahamas, Puerto Rico, Jamaica and Florida.
Plantings were successful in the Bahamas and Puerto Rico but did not arouse enough interest to cause further cultivation. Florida and Jamaica trials were failures. In recent years, test plantings have been made in Trinidad and Taiwan, and plants have fruited well in greenhouse culture in England. The principal areas of production in Mexico are the States of Morelos and Hidalgo. The former has about 32,000 acres (13,000 ha) with a total production of 101,366 tons.
There is great variation, not only in color and flavor of the numerous strains of Mexican husk tomato. Some require long days and others short days. Some mature early, others late. The husk may be long or short. The flesh may be soft and spongy or firm and crisp. A large number of selections has been made at the Campo Agricola Experimental de Zacatepec, in the State of Morelos, Mexico. The most promising, 'Rendidora', is more erect than the common type, the fruit is large, green, ripens 15 days earlier than others and gives 80% greater yield. Horticulturists at the Universidad de San Simón in Bolivia have long maintained a collection of various types received from Mexico.
The "Mayan husk tomato" selection at Iowa is semi-prostrate, vigorous, branching at a height of 4 to 6 in (10-15 cm); the stems are pale-green, smooth and succulent when young. The fruit is round, yellow, with light-yellow, firm flesh and mild-acid flavor. According to Dr. Margaret Menzel, an authority on the genus, the so-called Physalis macrocarpa, or "Golden Nugget Cape Gooseberry", offered by seedsmen in Australia, is really a yellow-fruited form of the Mexican husk tomato, P. ixocarpa.
The Mexican husk tomato is highly self-incompatible. When the flowering plants are bagged, no fruits are set. K.K. Pandey, while at the University of Ohio, studied this problem. He reported that only a few seedlings in a group produce rare fruits by natural-selfing and such fruits usually contain no seeds or only a small number. An occasional fruit may have 100 or more.
Climate and Soil
This species is not ultra-tropical but tropical and, like the tomato, is grown in summer in temperate regions. The plant needs full sun. It will grow in any soil suitable for tomatoes but not in wet situations.
The Mexican husk tomato is usually raised from seed and it takes about 2 1/4 oz (60 g) to plant an acre; 5 1/4 oz (150 g) to plant a hectare. In Puerto Rico, seeds saved from the first crop and kept for 6 months without refrigeration were planted and 80% germinated.
Cuttings should root easily. Heavy rains cause the plants to bend down to the ground and it has been observed that tips that touch the soil take root and the new shoots grow vigorously.
Ideal spacing for cv. 'Rendidora' is 16 in (40 cm) between plants and 4 ft (1.25 m) between rows.
From 4 to 6 seeds are planted 1/2 in (1.25 cm) deep in hills 2 ft (60 cm) apart in rows 5 ft (1.5 m) apart. When 4 to 5 in (10-12.5 cm) high, the seedlings are thinned to 1 plant per hill. In the midwestern United States, seedlings are raised in greenhouses and are transplanted when about 3 weeks old as soon as all likelihood of spring frosts is past. They will begin to bear 6 to 18 weeks later and continue for about 1 1/2 months.
In Bahamian trials, seeds were planted in mid-April. By mid-September, the plants were fruiting heavily. They reseeded themselves and a healthy clump of "volunteers" sprang up on the site. In Puerto Rico, seeds planted at Mayaguez produced an abundant crop in the winter of 1953-54. The plot was fertilized at the rate of 2 oz (56 g) per plant, side dressing, of 9-8-8 fertilizer. The plants were staked and tied twice and grew to a height of 5 ft (1.5 m).
Wild plants in Mexico flower from June to October. In the midwestern United States, flowering takes place in mid-June and fruits start to ripen in late July and fruiting continues until fall frosts. The plants bear during the summer months in South Africa; in northern India, both summer and winter.
With the Mexican husk tomato, falling of fruits before ripening is not uncommon, and, according to Dr. Melhus, they may be allowed to remain on the ground until fully colored. Collecting must be done every day. The green-skinned variety grown commercially by Mr. Jue was harvested as soon as it burst its husk, and the crop was then kept on hand 2 to 4 weeks for the husk to dry before the fruit was considered acceptable to the consumer. If left too long on the plant, there is much loss of flavor.
Individual plants may produce 64 to 200 fruits in a season. In test plantings at Ames, Iowa, the fruit yield averaged 2 12 lbs (1.1 kg) per plant; equal to approximately 9 tons per acre (20.2 MT/ha). In Mexico and India, yields of 7.5 to 10 tons per acre (17-22.5 MT/ha) have been reported.
The unhusked fresh fruits can be stored in single layers in a cool, dry atmosphere for several months. Mexican and Central American people may pull up the entire plant with fruits attached and hang it upside-down in a dry place until the fruits are needed.
Pests and Diseases
The Mexican husk tomato is subject to few pests and diseases. In Mexico, the main pest is the so-called mosquita blanca (see below). The larvae of Heliothis virescens attack the fruits. It has been found that various species of Trichogramma parasitize the eggs, found mainly on the underside of the leaves, though only in certain localities at certain seasons. In India, fruit and stem borers are troublesome during the rainy season but not in the winter. No insects attacked the plant in Puerto Rico. The two trials in Florida were at first promising, the plants flowering and setting fruit satisfactorily. However, as the fruits began to mature, they were attacked within the husk by a species of cutworm and only a few mature fruits were harvested. In Jamaica, seeds planted in late January produced vigorous and precocious plants which flowered when only 4 in (10 cm) high. Fruit-setting began in May and a high yield was expected but nearly all of the fruits were damaged by caterpillars before reaching maturity.
In Puerto Rico, no diseases were evident. In the Bahamas, only a slight incidence of leaf spot was observed. In Mexico, the husk tomato and the common tomato are both subject to a disease called chino or chahuixtle which occurs in irrigated plantings in Morelos. It is transmitted by the mosquita blanca, Trialeurodes vaporariorum.
This species, in contrast with the cape gooseberry, is used more largely as a vegetable than as a dessert fruit, though it is often consumed ripe, raw, out-of-hand. In Mexico, it is generally made into a sauce, salsa verde, for meats, alone or together with green chili peppers. Suggestions for use distributed by Iowa State College include recipes for stewing, frying, baking, cooking with chopped meat, making into soup, marmalade and dessert sauce. The fruit is an excellent addition to salads and curries. It has been utilized commercially for jam in Australia but the product is there considered inferior to that made from the cape gooseberry. The fruits, canned whole in Mexico, are sold domestically and in the western United States.
Food Value Per 100 g of Edible Portion*
|Phytin Phosphorus||7 mg|
|Ionisable Iron||1.0 mg|
|Carotene (Vitamin A)||80 I.U. or 0.061-0.074 mg|
|Ascorbic Acid||2-4.8 mg|
*According to analyses of the husked fruit made in Guatemala and India.
It is said in Mexico that a decoction of the calyces will cure diabetes.