Cucurbits. James R. Myers
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dried and pounded into a powder or made into a tea (G. pentophyllum). Seeds of squash, wax gourd, bottle gourd and other cucurbits are taken as anthelmintic medicine. Oil extracted from seeds of antidote vine (Fevillea cordifolia) is used medicinally to counteract the poison of a snakebite, to ward off dandruff and for an assortment of other ailments.
One of the most widely employed of the medicinal cucurbits is bitter gourd. Research has shown that this plant serves to control, though not cure, mild to moderately chronic cases of diabetes mellitus by increasing carbohydrate utilization. Medical investigators in China, Japan and India are testing species of Momordica for their purported analgesic (pain relief), abortifacient (causing abortion), immunosuppressive and anti-tumour properties. Similar laboratory research is ongoing for species of Trichosanthes (Rai et al., 2009; Liyanage et al., 2016). In 1989, compound Q (related to methane monooxygenase), which is an active principle extracted from Chinese snake gourd, received a lot of attention when medical professionals began to study it as a treatment against the human immunodeficiency virus (HIV). Bitter gourd has also been used to combat HIV infection.
The bioactive compounds in cucurbits also serve other purposes. People in Mexico have long taken advantage of the saponins in fruit of wild Cucurbita for creating a frothy cleansing soap. Similarly, Nigerians use the leaves of balsam apple to clean metals, and the leaves and fruit as a body wash. Saponins in seeds and fruit make an effective component in fish poison. For example, luffa is used for that purpose in Australia. Fruit of casabanana are hung in the house as a room deodorizer. Various cucurbits are used to repel insects. The Chinese spray extracts of Luffa and Momordica on crops to control spider mites and other agricultural pests (Yang and Tang, 1988). In North Africa, Arabian camel herders smear a rind extract of colocynth on water bags to keep camels away.
Cucurbit fruit sometimes become objects of decoration and art. In the USA, ornamental gourds and turban squashes provide autumn table decorations, and pumpkins (C. pepo) are carved and illuminated with candles to celebrate the holiday of Halloween, as well as celebrations of autumn harvest. The ultimate degree of artistic expression has been reached with bottle gourds. Many different cultures independently developed the custom of carving, painting and otherwise decorating the gourds that were so useful to them. The art of gourd decoration is most highly developed in Peru, where detailed pyro-engraving techniques produce fine-art gourdcraft exported around the world.
Finally, some cucurbits are grown as ornamental plants. In addition to its lacy leaves and colourful fruit, the fragrant blossoms of bitter gourd make this species a very appealing trellis ornamental. Bitter gourd has been grown in glasshouses in the UK since Victorian times. The beautiful white, fringed petals of snake gourd and its long serpent-like fruit, dangling beneath a garden arbour, make for a picturesque sight. The spiny fruit of teasel gourd and African horned melon and the explosive fruit of squirting and exploding cucumbers have brought these cucurbits into commercial trade as well. The most recent horticultural trend affecting cucurbits is the passion for succulents. Collectors are beginning to learn of and trade among themselves the caudiciform cucurbits of Africa (e.g. Gerrardanthus and Trochomeria), Madagascar (Seyrigia and Xerosicyos) and North America (Marah and Ibervillea).
COMMERCIAL PRODUCTION AREAS AND IMPORTANCE
According to the Food and Agriculture Organization (FAO) of the United Nations, watermelon is the most popular cucurbit in the world (Table 2.1). The FAO estimated that 3,477,000 ha of watermelon were harvest worldwide in 2014, producing 111,009,000 t of fruit. Next in total world production were cucumber, melon, and then squash and pumpkin. All of these crops have seen increases in production since the 1970s (Table 2.1). The greatest growth in harvested area (355%) was seen in pumpkins and squashes, but an approximate 200% increase was also seen for other cucurbit crops. In watermelon, production has increased by 444% over the past three decades. Cucumber production has seen a 343% increase in production over the same time period.
Table 2.1. Leading countries in the production of cucurbits.
China remains the leading producer of the major cucurbit crops in the world. Although China is also a prominent producer of luffa, wax gourd and other cucurbits of Asian origin, production statistics for these crops are not readily available. China exports various cucurbit products, including fresh fruit, watermelon and squash seeds, and dried fruit of the medicinal (and low-calorie sweetener) monk fruit or luo-han-guo (Fig. 2.2). In 1990, the Chinese Agricultural Department estimated that 30% of the land in China that was devoted to vegetable production was sown in cucurbits (Yang and Walters, 1992). In 2014, the second leading producer of watermelons and melons was Turkey. Russia was the second leading producer of cucumbers, and India was second for squash and pumpkins (Table 2.1).
Fig. 2.2. Luohan beverage mix from China. Seeds and fruit of luo-han-guo are pictured on the package.
It is very difficult to obtain reliable statistics on cucurbit production in many countries because governmental statistics are not readily available to the public and data gathering and reporting procedures vary from country to country. Also, different agencies report different statistics for the same country.
Besides the major crops, there are some minor cucurbit crops of international commercial importance. Already mentioned are the fruit of monk fruit (luo-han-guo) exported from China. China and Japan both export other cucurbits of medicinal interest, such as preparations of Gynostemma and Trichosanthes, which are finding their way into the American herbal medicine market. Medicinal preparations of colocynth have a long history of trade from African to European pharmacies. Fruit of African horned melon that are commercially produced in New Zealand appear in American and European food markets sporting the trade name ‘kiwano’. Because of expanding demand, Kenya and Israel have also become important exporters of this attractive fruit. Japan and Central America are the major exporters of luffa sponges. In the early 1940s, when luffa sponges were an important source of industrial filters, Brazil exported almost 2 million sponges per year to the USA alone. In 1985, Costa Rica was the leading exporter of chayote. In 2011, Mexico became the leading exporter of chayote to the USA with 19,500 t being exported, though Costa Rica’s production was similar. Both Costa Rica and Mexico still ship large amounts of chayote to other Latin American countries and to Europe. Decorated bottle gourds are a source of foreign currency in Peru. Snake gourd and bitter gourd (Fig. 2.3) are bottled or canned for export in Asia and have been for decades.
Fig. 2.3. Bitter gourd, immature fruit and canned. (Reprinted by permission from The New York Botanical Garden, © 1988, Economic Botany 42, 287, J. Ruh and J. Thieret, photographers, in Walters and Decker-Walters, 1988.)
Cucurbits are important in the international seed trade. In addition to the major food crops, seed companies offer germplasm of other edible and ornamental cucurbits such as luffa, wax gourd, bottle gourd, bitter gourd, stuffing cucumber and casabanana.