1.2- Genus Cucurbita Cucurbita(Latin for gourd) is a genus of herbaceousvine in the gourd familyCucurbitaceae, also known as cucurbits, native to the Andes and Mesoamerica. Five species are grown worldwide for their edible fruit, variously known as squash, pumpkin, or gourd depending on species, variety, and local parlance, and seeds. First cultivated in the Americas before being brought to Europe after the discovery of the New World, plants in the genus Cucurbita are important sources of human food, beverages, and oil. Most Cucurbita species are herbaceous vines that grow several meters in length and have tendrils, but non-vining "bush" cultivars of Cucurbita pepo and Cucurbita maxima have also been developed. The yellow or orange flowers on a Cucurbita plant are of two types: female and male. The female flowers produce the fruit and the male flowers produce pollen. Many North and Central American species are visited by specialist beepollinators, but other insects with more general feeding habits such as honey bees also visit. The fruits of the Cucurbita genus are good sources of several nutrients such as vitamin A, vitamin C, niacin, folic acid, and iron, and like all plant products are free of cholesterol. The plants contain the toxins cucurbitin, cucurmosin, and cucurbitacin. Cucurbita fruits have played a role in human culture for at least 2,000 years. They are often represented in Moche ceramics from Peru. After Christopher Columbus's arrival in the New World, paintings of squashes started to appear in Europe early in the sixteenth century. Among other uses, extracts are used in cosmetics for dry and sensitive skin. The fruits have many culinary uses including pumpkin pie, biscuits, bread, desserts, puddings, and soups. Pumpkins and other Cucurbita fruits are celebrated in festivals and in flower and vegetable shows in many countries. Other kinds of gourd, also called bottle-gourds, are native to Africa and belong to the genus Lagenaria, which is in the same family and subfamily as Cucurbita but in a different tribe. These gourds are used as utensils or vessels.
2.1- Description + Plant Most Cucurbita species are climbing annual vines; they are also mesophytes, plants which require a more or less continuous water supply. The less numerous perennial species grow in tropical zones and are xerophytes, plants which tolerate dry conditions. The stems in some species are angular. All of the above-ground parts may be hairy with various types of trichomes, which are often hardened and sharp. Growing 5 to 15 meters (16 to 49 ft) in height or length, the plant stem produces tendrils to help it climb adjacent plants and structures or extend along the ground. Most species do not readily root from the nodes; a notable exception is Cucurbita ficifolia, and the four other cultivated mesophytes do this to a lesser extent. The vine of the perennial Cucurbita can become semiwoody if left to grow. There is wide variation in size, shape, and color among Cucurbita fruits, and even within a single species. Cucurbita ficifolia is an exception, being highly uniform in appearance. The morphological variation in the species Cucurbita pepo and Cucurbita maxima is so vast that its various subspecies and cultivars have been misidentified as totally separate species. + Leaves The typical cultivated Cucurbita species has five-lobed or palmately divided leaves with long petioles, with the leaves alternately arranged on the stem. Spring-like tendrils grow from each node and are branching in some species. Cucurbita argyrosperma has ovate-cordate (egg-shaped to heart-shaped) leaves. The shape of Cucurbita pepo leaves varies widely. Cucurbita moschata plants can have light or dense pubescence. Cucurbita ficifolia leaves are slightly angular and have light pubescence. The leaves of all four of these species may or may not have white spots. + Flowers There are male (staminate) and female (pistillate) flowers (unisexual flowers) on a single plant (monoecious), and these grow singly, appearing from the leaf axils. Flowers have five fused yellow to orange petals (the corolla) and a green bell-shaped calyx. Male flowers in Cucurbitaceae generally have five stamens, but in Cucurbita there are only three, and their anthers are joined together so that there appears to be one. Female flowers have thick pedicels, and an inferior ovary with 3-5 stigmas that each have two lobes. The female flowers of Cucurbita argyrosperma and Cucurbita ficifolia have larger corollas than the male flowers. Female flowers of Cucurbita pepo have a small calyx, but the calyx of Cucurbita moschata male flowers is comparatively short. + Fruits Cucurbita fruits are large and fleshy. Botanists classify the Cucurbita fruit as a pepo, which is a special type of berry derived from an inferior ovary, with a thick outer wall or rind with hypanthium tissue forming an exocarp around the ovary, and a fleshy interior composed of mesocarp and endocarp. The term "pepo" is used primarily for Cucurbitaceae fruits, where this fruit type is common, but the fruits of Passiflora and Carica are sometimes also considered pepos. Fruit size varies considerably: wild fruit specimens can be as small as 4 centimeters (1.6 in) and some domesticated specimens can weigh well over 300 kilograms (660 lb). The current world record was set in October 2014 by John Hawkley of Napa County, California with a 933.5 kilogram (2,058 lb) pumpkin. + Seeds The seeds, which are attached to the ovary wall (parietal placentation) and not to the center, are large and fairly flat with a large embryo that consists almost entirely of two cotyledons.
2.2- Origin and Distribution + Origin: Cucurbita (Latin for gourd) is a genus of herbaceousvine in the gourd familyCucurbitaceae, also known as cucurbits, native to the Andes and Mesoamerica. The ancestral species of the genusCucurbitawere present in the Americas before thearrival of humans,and are native to theNew World. The likely center of origin is southern Mexico, spreading south through what is now known as Mesoamerica, on into South America, and north to what is now the southwestern United States. Archaeological investigations have found evidence of domestication of Cucurbita going back over 8,000 years from the very southern parts of Canada down to Argentina and Chile. Centers of domestication stretch from the Mississippi River watershed and Texas down through Mexico and Central America to northern and western South America.Of the 27 species that Nee delineates, five are domesticated. Four of them,Cucurbita argyrosperma,Cucurbita ficifolia, Cucurbita moschata, andCucurbita pepo, originated and were domesticated inMesoamerica; for the fifth,Cucurbita maxima, these events occurred in South America. + Distribution: Though native to the western hemisphere,Cucurbita began to spread to other parts of the world after Christopher Columbus's arrival in the New World in 1492. In 2012: - Top 10 of squash producers included: China, India, Russia, USA, Iran, Egypt, Mexico, Ukraine, Italy and Turkey. Top 10 total of squash production got 15,663,449 (metric tons). - Top 10 of Cucumber producers of included: China, Iran,Turkey, Russia, USA, Ukraine, Spain, Egypt, Japan and Indonesia. Top 10 total of cucumber production got 49,075,599 (metric tons). - Top 10 of Watermelon producers included: China, Turkey, Iran, Brazil, USA, Egypt, Uzbekistan, Russia, Mexico and Algeria. Top 10 total of Watermelon production got 73,490,835 (metric tons).
2.3- Biological characteristics of the Genus Cucurbita + Phylogeny The full phylogeny of this genus is unknown, and research is ongoing in 2014. The following cladogram of Cucurbita phylogeny is based upon a 2002 study of mitochondrial DNA by Sanjur and colleagues.
+ Reproductive biology All species ofCucurbitahave 20 pairs of chromosomes.Many North and Central American species are visited by specialist pollinatorsin theapidtribeEucerini, especially the generaPeponapisandXenoglossa, and thesesquash beescan be crucial to the flowers producing fruit after pollination. When there is more pollen applied to the stigma, more seeds are produced in the fruits and the fruits are larger with greater likelihood of maturation, an effect calledxenia. Competitively grown specimens are therefore often hand-pollinated to maximize the number of seeds in the fruit, which increases the fruit size; this pollination requires skilled technique.Seedlessnessis known to occur in certain cultivars ofCucurbita pepo. The most critical factors in flowering and fruit set are physiological, having to do with the age of the plant and whether it already has developing fruit.Theplant hormonesethyleneandauxinare key in fruit set and development.Ethylene promotes the production of female flowers. When a plant already has a fruit developing, subsequent female flowers on the plant are less likely to mature, a phenomenon called "first-fruit dominance",and male flowers are more frequent, an effect that appears due to reduced natural ethylene production within the plant stem.Ethephon, a plant growth regulator product that is converted to ethylene after metabolism by the plant, can be used to increase fruit and seed production. The plant hormone gibberellin, produced in the stamens, is essential for the development of all parts of the male flowers. The development of female flowers is not yet understood. Gibberellin is also involved in other developmental processes of plants such as seed and stem growth.
Note!Squash needs insects to carry out the pollinating process for setting fruits. If the insects are not available in your area, the pollinating process can be done manually, by picking up male flowers and transferring pollens to femal flowers (face-to-face touching the center part of flowers). This process should be carried out when flowering is active during the daytime.
+ Germination and seedling growth Seeds with maximumgerminationpotential develop (inC. moschata) by 45 days after anthesis, and seed weight reaches its maximum 70 days after anthesis.Some varieties of C. pepogerminate best with eight hours of sunlight daily and a planting depth of 1.2 centimeters (0.47 in). Seeds planted deeper than 12.5 centimeters (4.9 in) are not likely to germinate.InC. foetidissima, a weedy species, plants younger than 19 days old are not able to sprout from the roots after removing the shoots. In a seed batch with 90 percent germination rate, over 90 percent of the plants had sprouted after 29 days from planting. Experiments have shown that when more pollen is applied to the stigma, as well as the fruit containing more seeds and being larger (the xenia effect mentioned above), the germination of the seeds is also faster and more likely, and the seedlings are larger. Various combinations of mineral nutrients and light have a significant effect during the various stages of plant growth. These effects vary significantly between the different species of Cucurbita. A type of stored phosphorus called phytate forms in seed tissues as spherical crystalline intrusions in protein bodies called globoids. Along with other nutrients, phytate is used completely during seedling growth. Heavy metal contamination, including cadmium, has a significant negative impact on plant growth. Cucurbita plants grown in the spring tend to grow larger than those grown in the autumn.
3- Growing Cucurbita plants on the World
3.1-History and domestication The ancestral species of the Genus Cucurbita were present in the Americas before the arrival of humans, and are native to the New World. The likely center of origin is southern Mexico, spreading south through what is now known as Mesoamerica, on into South America, and north to what is now the southwestern United States. Evolutionarily speaking, the genus is relatively recent in origin, dating back only to the Holocene, whereas the Cucurbitaceae family, in the shape of seeds similar to Bryonia, dates to the Paleocene. No species within the genus is entirely genetically isolated. Cucurbita moschata can intercross with all the others, though the hybrid offspring may not themselves be fertile unless they become polyploid. The genus was part of the culture of almost every native peoples group from southern South America to southern Canada. Modern-day cultivated Cucurbita are not found in the wild. Genetic studies of the mitochondrial genenad1 show there were at least six independent domestication events of Cucurbita separating domestic species from their wild ancestors. Species native to North America include Cucurbita digitata(calabazilla),andCucurbita foetidissima(buffalo gourd),Cucurbita palmata(coyote melon), andCucurbita pepo.Some species, such as Cucurbita digitata and Cucurbita ficifolia, are referred to as gourds. Gourds, also called bottle-gourds, which are used as utensils or vessels, belong to the genus Lagenaria and are native to Africa. Lagenaria are in the same family and subfamily as Cucurbita but in a different tribe. The earliest known evidence of the domestication of Cucurbita dates back at least 8,000 years ago, predating the domestication of other crops such as maize and beans in the region by about 4,000 years. This evidence was found in the Guilá Naquitz cavein Oaxaca, Mexico, during a series of excavations in the 1960s and 1970s, possibly beginning in 1959. Solid evidence of domesticated Cucurbita pepo was found in the Guilá Naquitz cave in the form of increasing rind thickness and larger peduncles in the newer stratification layers of the cave. By c. 8,000 years BP the Cucurbita pepo peduncles found are consistently more than 10 millimeters (0.39 in) thick. Wild Cucurbita peduncles are always below this 10 mm barrier. Changes in fruit shape and color indicate that intentional breeding of Cucurbita pepo had occurred by no later than 8,000 years BP. During the same time frame, average rind thickness increased from 0.84 millimeters (0.033 in) to 1.15 millimeters (0.045 in). Squash was domesticated first, followed by maize and then beans, becoming part of the Three Sisters agricultural system of companion planting. The English word "squash" derives from askutasquash (a green thing eaten raw), a word from the Narragansett language, which was documented by Roger Williams, the founder of Rhode Island, in his 1643 publication A Key Into the Language of America. Similar words for squash exist in related languages of the Algonquianfamily.
3.2- Major Species of the GenusCucurbita 1- Species Cucurbita argyrosperma - Cushaw pumpkin Cucurbita argyrosperma (synonymCucurbita mixta) - cushaw pumpkin; origin: Panama, Mexico. Cucurbita argyrospermais not as widespread as the other species. The wild formCucurbita argyrospermasubsp.sororia is found fromMexicotoNicaragua, and cultivated forms are used in a somewhat wider area stretching from Panama to the southeastern United States.It was probably bred for its seeds, which are large and high inoilandprotein, but its flesh is of poorer quality than that ofCucurbita moschataandCucurbita pepo. It is grown in a wide altitudinal range: from sea level to as high as 1,800 meters (5,900 ft) in dry areas, usually with the use of irrigation, or in areas with a defined rainy season, where seeds are sown in May and June.
2- Species Cucurbita ficifolia - Figleaf gourd, Chilacayote Cucurbita ficifolia- figleaf gourd, chilacayote; origin: Mexico, Panama, northern Chile and Argentina. The origin of Cucurbita ficifolia is in Latin America, most likely southern Mexico, Central America, or the Andes. It grows at altitudes ranging from 1,000 meters (3,300 ft) to 3,000 meters (9,800 ft) in areas with heavy rainfall. It does not hybridize well with the other cultivated species as it has significantly different enzymes and chromosomes.
3- Species Cucurbita maxima - Giant pumpkin Cucurbita maxima, one of at least five species of cultivated squash, is one of the most diverse domesticated species. This species originated in South America from the wild Cucurbita andreana over 4000 years ago. All giant pumpkins (>100 pounds (45 kg)) are of this species, including the largest pumpkins ever documented, which have attained a size of over 2,000 pounds (910 kg). The large red-orange squashes often seen at Halloween in the United States are Cucurbita maxima, but not to be confused with the orange type used for jack-o-lanterns, which are Cucurbita pepo. The seed of Cucurbita maxima is used in treating parasites in animals.
4- Species Cucurbita moschata - Butternut squash Cucurbita moschata - butternut squash, 'Dickinson' pumpkin, golden cushaw; origin: Bolivia, Colombia, Ecuador, Mexico, Panama, Puerto Rico, Venezuela. Cucurbita moschatais native to Latin America, but the precise location of origin is uncertain. It has been present in Mexico, Belize, Guatemala, and Peru for 4,000-6,000 years and has spread to Bolivia, Ecuador, Panama, Puerto Rico, and Venezuela. This species is closely related to Cucurbita argyrosperma. A variety known as the Seminole Pumpkin has been cultivated in Florida since before the arrival of Columbus. Its leaves are 20 to 30 centimeters (8 to 12 in) wide. It generally grows at low altitudes in hot climates with heavy rainfall, but some varieties have been found above 2,200 meters (7,200 ft). Groups of Cucurbita moschata include Cheese, Crookneck (Cucurbita moschata), and Bell.
5- Species Cucurbita pepo - Field pumpkin, Summer squash, Zucchini Cucurbita pepo - field pumpkin, summer squash, zucchini, vegetable marrow, courgette, acorn squash; origin: Mexico, USA Cucurbita pepois one of the oldest, if not the oldest, domesticated species with the oldest known locations beingOaxaca, Mexico, 8,000-10,000 years ago, andOcampo, Tamaulipas, Mexico, about 7,000 years ago. It is known to have appeared inMissouri, United States, at least 4,000 years ago.Debates about the origin ofC. pepohave been on-going since at least 1857.There have traditionally been two opposing theories about its origin: 1) that it is a direct descendant ofCucurbita texanaand 2) thatCucurbita texanais merelyferalCucurbita pepo. A more recent theory by botanist Thomas Andres in 1987 is that descendants ofCucurbita fraternahybridized withCucurbita texana,resulting in two distinct domestication events in two different areas: one in Mexico and one in the eastern United States, withCucurbita fraterna andCucurbita texana, respectively, as the ancestral species. Cucurbita pepomay have appeared in the Old World before moving from Mexico into South America. It is found from sea level to slightly above 2,000 meters (6,600 ft). Leaves have 3-5 lobes and are 20-35 centimeters (8-14 in) wide. All the subspecies, varieties, and cultivars are interfertile. In 1986 Paris proposed a revised taxonomy of the edible cultivated Cucurbita pepo based primarily on the shape of the fruit, with eight groups . All but a few Cucurbita pepo cultivars can be included in these groups. There is one non-edible cultivated variety: Cucurbita pepo var. ovifera.
3.4- Production The family Cucurbitaceae has many species used as human food. Cucurbita is one of the most important of those, with the various species being prepared and eaten in many ways. Although the stems and skins tend to be more bitter than the flesh, the fruits and seeds of cultivated varieties are quite edible and need little or no preparation. The flowers and young leaves and shoot tips can also be consumed. The seeds and fruits of most varieties can be stored for long periods of time, particularly the sweet-tasting winter varieties with their thick, inedible skins. Summer squash have a thin, edible skin. The seeds of both types can be roasted, eaten raw, made into pumpkin seed oil, ground into a flour or meal, or otherwise prepared. Squashes are primarily grown for the fresh food market. The Food and Agriculture Organization of the United Nations (FAO) reported that the ranking of the top five squash-producing countries was stable from 2005-2009. Those countries are: China, India, Russia, the United States, and Egypt. By 2012, Iran had moved into the 5th slot, with Egypt falling to 6th. The top 10 countries in terms of metric tons of squashes produced are:
Top ten squash producers - 2012: Country Production (metric tons) 1- China 6,140,840 2- India 4,424,200 3- Russia 988,180 4- USA 778,630 5- Iran 695,600 6- Egypt 658,234 7- Mexico 522,388 8- Ukraine 516,900 9- Italy 508,075 10- Turkey 430,402 Top 10 total 15,663,449
The only additional countries that rank in the top 20 where squashes are native are Cuba, which ranks 14th with 347,082 metric tons, and Argentina, which ranks 17th, with 326,900 metric tons. In addition to being the 4th largest producer of squashes in the world, the United States is the world's largest importer of squashes, importing 271,614 metric tons in 2011, 95 percent of that from Mexico. Within the United States, the states producing the largest amounts are Florida, New York, California, and North Carolina. This is how Cucurbita compares to several other major Cucurbitaceae crops in terms of crop tonnage harvested:
Top ten cucumber producers - 2012: Country Production (metric tons) 1- China 40,710,200 2- Iran 1,811,630 3- Turkey 1,739,190 4- Russia 1,161,870 5- USA 883,360 6- Ukraine 860,100 7- Spain 682,900 8- Egypt 631,408 9- Japan 587,800 10- Indonesia 547,141 Top 10 total 49,075,599
Top ten watermelon producers - 2012 Country Production (metric tons) 1- China 56,649,725 2- Turkey 3,683,100 3- Iran 3,466,880 4- Brazil 1,870,400 5- USA 1,866,660 6- Egypt 1,637,090 7- Uzbekistan 1,182,400 8- Russia 1,151,580 9- Mexico 1,036,800 10- Algeria 946,200 Top 10 total 73,490,835