Pumpkin

Economic importance

Pumpkin with yellow flesh contains much phosphorus, carotene, and phytoncides. The fruits are used to make candied fruit and honey (from the juice).

Fodder pumpkin varieties are used as livestock feed and have lactogenic properties. 100 kg of fodder pumpkin fruits correspond to 10 feed units and contain 70 g of digestible protein.

Average chemical composition of pumpkin fruits: dry matter — 8–12%; protein — 1.0%; carbohydrates — 6.5%; pectin substances — 1.0%; fiber — 0.7%; ash — 0.6%. It also contains iron and vitamins. In carotene content it surpasses carrots.

It is used raw, baked, steamed, and fried; it can be used to make puree, jam, and candied fruit.

Honey plant.

It has been used for medicinal purposes since ancient times, for hyperacidity, gastric catarrh, ulcers, inflammation of the colon, constipation, obesity, edema, helminthiasis, burns, rash, and insomnia.

Pumpkin seeds contain up to 52% edible oil.

One of the best fodder crops in dry and dry-steppe zones. It stores well for 1–2 years. 100 kg of pumpkin fruits correspond to 8–15 feed units and contain 0.7–1.1 kg of digestible protein. 100 kg of silage — 15.5 feed units and 1.3 kg of protein.

During domestication in pre-Columbian times, people selected fruits with non-lignified rind in pumpkins that were usually eaten ripe. The hard rind, caused by one dominant allele in Cucurbita pepo, occurs in many zucchini varieties that are eaten before lignification of the rind becomes unacceptable.

Native Americans dried strips of flesh in the sun for preservation. Today zucchini is usually cooked by boiling or frying, and pumpkins by baking or boiling. Zucchini usually have white flesh and low dry matter, while pumpkins with orange flesh are rich in carotenoids and high in dry matter.

In Southern Europe, butternut squash (Cucurbita moschata) is eaten as a summer squash, which led to the development of ‘Tromboncino’ varieties. These varieties retain the vine but bear slender, long-necked fruits. Immature fruits are usually eaten at 15–20 cm length. When ripe, fruits can reach 1 m in length. Many consider the quality of ‘Tromboncino’ fruits in the immature state superior to that of zucchini (Cucurbita pepo). They have more total dry matter, taste more like mature pumpkin, and the fruits have a long seedless neck. In Argentina, bush varieties of large-fruited pumpkin (Cucurbita maxima), known as ‘sapallito’, are a popular type of summer squash.

Some zucchini varieties (Cucurbita pepo) are eaten almost mature. In the Middle East, almost mature ‘Cousa’ fruits are stuffed with meat and other ingredients and then baked.

In the USA, the best-known use of pumpkins of the species Cucurbita pepo is making Halloween lanterns. Every autumn, orange, round or oval fruits are carved into grotesque faces and illuminated from within with candles.

Commercial canned pumpkin pie mix may be made from Cucurbita maxima or Cucurbita moschata. Historically Cucurbita pepo had a long tradition of use in the USA, but fruits of the other two species make better pies, and Cucurbita pepo is no longer used. Varieties of Cucurbita moschata such as ‘Ultra’ and ‘Dickinson Field’, and Cucurbita maxima such as ‘Golden Delicious’, are also processed and sold as canned or frozen pumpkin. For canning, varieties with orange or tan rind are preferred. If a small piece of rind accidentally gets into the canned product, it is less noticeable than in varieties with green fruits. Varieties used for processing have soft rind with total dry matter from 5% to 9% and soluble dry matter from 6% to 12%. Carotenoid-rich orange fruits of Cucurbita maxima, which also have fine texture and flavor, are used as puree for baby food.

Despite being banned in the USA since the 1970s, the organophosphate pesticide DDT and its breakdown products dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) persist in soil for decades. Other chlorinated hydrocarbon pesticides may include lindane, aldrin, and dieldrin. Species of Cucurbita spp. have extensive root systems and are known as hyper-accumulators of DDE and DDD (White, 2002). Companies growing cucurbit crops on soils where DDT was previously used are required to test for these compounds; if their content exceeds the FDA threshold of 0.1 ppm, they cannot sell products made from pumpkins grown on those fields. This is especially important for puree intended for baby food.

Mature fruits of Cucurbita ficifolia are used as winter squash, and immature fruits as summer squash. Cooked stringy flesh is used to make an Aztec delicacy called “angel’s hair.” The tasteless fruits contain a proteolytic enzyme that may in the future have commercial value for the food industry. Stem tips and leaves are used as greens, flowers are served as a seasoning, and seeds are roasted and eaten.

Most likely, pumpkin was originally domesticated for its seeds, rich in proteins and lipids. Besides the fact that wild pumpkins are very bitter, they have a thick inedible rind and little edible pericarp, but the seeds were easily accessible and relatively easy to process to remove bitterness (Hart, 2004). The main processing effort for seeds of modern pumpkin varieties is removing the seed coat, since bitterness has been bred out of most varieties. In Latin America, seeds of Cucurbita argyrosperma with hulls are eaten as “pepitas.” Hull-less pumpkin seeds of Cucurbita pepo obtained from Styrian oil pumpkins are becoming increasingly popular because they require minimal preparation. Varieties of Cucurbita maxima such as ‘Golden Delicious’ are an important snack in Asia, where they are consumed like sunflower seeds in the USA.

Pumpkin has been an important food in Mexico for centuries. Fruits are processed and eaten in various ways. Seeds are a popular snack and are also ground into flour used to prepare special sauces. Flowers are eaten stuffed or fried; they add color and aroma to soups, stews, and salads. Stems, tops, and roots of some species are also eaten.

Native peoples of the New World used pumpkin seeds as a source of cooking oil and for medicinal purposes as a diuretic, antipyretic, and anthelmintic. The flesh of wild species, when rubbed, forms a saponin-rich foam that was used to wash clothes.

In recent years, pumpkin has attracted considerable attention due to the nutritional and health-promoting properties of bioactive compounds obtained from its seeds and fruits. The chemical and pharmacological properties of extracts of Cucurbita moschata from its stems, seeds, and fruits have been studied. These studies showed that Cucurbita moschata has broad bioactive properties, such as hepatoprotective (Makni et al., 2008), antidiabetic (Jiang, 2011), anticancer (Zhang et al., 2012), and anti-obesity (Lee et al., 2010). In South and Central America, Cucurbita moschata has many traditional medicinal uses. Seeds are roasted and eaten as an anthelmintic, and also used as a diuretic; a preparation from flowers was used to treat measles and smallpox. Fruits and seeds are used in Ayurveda to treat bleeding of pulmonary organs, rheumatism, and urolithiasis. There is pharmacological confirmation of ethnomedical claims about the benefits of this plant as an anti-ulcer remedy (Govindani et al., 2012).

History of cultivation

Based on isozyme bands, Puchalski and Robinson (1990) classified species of Cucurbita into seven phylogenetic groups. Cucurbita moschata and Cucurbita argyrosperma were included in one group, while other cultivated species were placed in different groups. Despite being in the same phylogenetic line, Cucurbita moschata and Cucurbita argyrosperma were probably domesticated from different wild ancestors, as were other cultivated squashes. The original phylogeny proposed by Puchalski and Robinson (1990) is supported by genomic sequence analysis (Montero-Pau et al., 2017).

Most species of Cucurbita originate from North or Central America, but several species, including Cucurbita maxima, are native to South America. Because wild fruits of this genus are bitter and inedible, early gatherers probably first collected fruits for their edible seeds or for using the durable rind as containers. These uses eventually led to the domestication of species with edible fruits. From these origins, squash, along with maize and beans, became a staple in the diet of the Aztec, Inca, and Maya civilizations in Latin America.

According to archaeological data, wild populations of Cucurbita pepo in Mexico and eastern USA appeared about 5,000–10,000 years ago (Smith, 1997a). Cucurbita pepo was the earliest domesticated in southern Mexico and southwestern USA as early as 8000 BCE. Domestication of this species apparently occurred independently in these two areas (Decker, 1988), with domestication in eastern USA occurring about 5,000 years later than in Mexico (Smith, 2006). American varieties ssp. ovifera (L.) Decker var. ovifera, which include various squashes and most ornamental pumpkins, were probably selected mainly from wild populations of var. ozarkana Decker-Walters inhabiting the Mississippi River Valley. However, populations in Texas (var. texana (Scheele) Decker) and northeastern Mexico (ssp. fraterna (Bailey) Andres) may also have contributed to the genetic evolution of these varieties. The wild ancestor of the Mexican lineage of cultivated varieties (ssp. pepo), which includes pumpkins and vegetable squashes, is currently unknown and may be extinct (Decker-Walters et al., 1993). Interestingly, for several thousand years between Cucurbita pepo var. pepo and Cucurbita pepo var. ovifera, no gene introgression occurred, although human migrations certainly took place and domestication regions were not so far apart.

Cucurbita pepo was the first pumpkin species introduced to Europe. It appears in the Livre d’Heures d’Anne de Bretagne, illustrated between 1505 and 1508 (Paris et al., 2006). Images of fruits and flowers of pumpkin forms of Cucurbita pepo are present at the Villa Farnesina in Rome in vegetation festoons separating spandrels, and were illustrated between 1509 and 1517 (Janick and Paris, 2006). Only after the publication of Fuchs’s “De Historia Stirpium” (1543) did any species of Cucurbita appear in herbals. Some fruits depicted in ancient European herbals do not differ from modern varieties. Exquisite detailed images giving insight into the diversification of Cucurbita pepo in Europe and the origin of summer squash forms can be seen in paintings by Antoine Nicolas Duchesne (Paris et al., 2000). Secondary diversification of pumpkin and vegetable squash varieties occurred in Asia Minor (Paris, 2001). Today Cucurbita pepo is grown worldwide.

Cucurbita moschata was cultivated in Mexico, South America, and southwestern USA in pre-Columbian times. It may have been domesticated independently in Mexico (by 5000 BCE) and northern South America; its uniqueness lies in being distributed in two different native areas — a main one in Mexico and a minor one in northern South America (Whitaker and Bemis, 1975). However, the wild ancestor of Cucurbita moschata is currently unknown. Archaeologists have found traces of Cucurbita moschata at Peruvian sites dated 4000–3000 BCE and at Mexican sites dated 1440–400 BCE, indicating a long history of domestication and cultivation. As a cultivated plant, this species migrated through the Caribbean islands, giving rise to various local calabaza varieties. When it reached Florida, Native Americans developed a separate variety called “Seminole pumpkin.” Additional diversification of varieties occurred in some areas of Asia and Africa. There are reports of images of Cucurbita moschata at the Villa Farnesina dating to the early 16th century (Janick and Paris, 2006), but overall there are fewer illustrations of this species in European art and herbals.

Cucurbita argyrosperma appears to have been domesticated in southern Mexico, where archaeological evidence of cultivation dates back 5,100 years (Smith, 1997b). Wild populations of ssp. sororia (Bailey) Merrick & Bates, found in Mexico and Central America, gave rise to the domesticated subspecies (ssp. argyrosperma). Landraces of ssp. argyrosperma var. argyrosperma may have been selected first. The other two variety groups, var. callicarpa Merrick & Bates and var. stenosperma (Pang.) Merrick & Bates, probably originated from northern and southern varieties of var. argyrosperma, respectively (Merrick, 1990). Weedy populations of var. palmeri (Bailey) Merrick & Bates are considered escapes of var. callicarpa that may have undergone introgression with ssp. sororia. Today Cucurbita argyrosperma is cultivated in Mexico, Latin America, the Caribbean, southwestern USA, and Asia, but has less commercial importance than Cucurbita pepo, Cucurbita maxima, or Cucurbita moschata.

Cucurbita maxima ssp. andreana (Naud.) Filov, a bitter-fruited native of Argentina and Uruguay, as evidenced by excavated seeds dated 1200 CE (Vishnu Swarup, 2006), is the wild ancestor of domesticated ssp. maxima, and the two readily hybridize. This species was first encountered by the Spanish when their explorations reached the Pacific coast of South America in the 16th century, and the species appears to be illustrated at Villa Farnesina (Janick and Paris, 2006; Formiga and Myers, 2019). Cucurbita maxima species did not reach North America until they were brought by sailing ships from South America to the northeastern USA in the 18th century. One of the early introductions was named ‘Valparaiso’, presumably from that city in Chile. Well adapted to temperate climates, Cucurbita maxima species were especially popular in northern US states, Canada, and Europe. Today Cucurbita maxima is cultivated worldwide, with significant production in South America, India, and Africa. Kabocha (buttercup) is a huge export item to Asia for both Mexico and New Zealand, and Cucurbita maxima ‘Jarradale’ (blue/gray crown-type squash) is a pumpkin grown for local consumption in New Zealand and Australia. It is also widely cultivated in Turkey, and in Poland breeding of Cucurbita maxima has been ongoing for several years, including use of varieties as feed for cattle. Because this species is generally more cold-hardy than Cucurbita argyrosperma, Cucurbita moschata, and Cucurbita pepo, it can be grown at higher latitudes and elevations.

Cucurbita ficifolia is called Malabar gourd because it was once thought to be of Asian origin. However, like other pumpkins, its origin is in the Americas, probably in the high mountain regions of Mexico. This cold-hardy species, growing at elevations up to 2,600 m, was also cultivated in prehistoric times in the Andes mountains of Peru. It reached Asia on sailing ships soon after the Columbian Exchange began. The fruits have a hard rind and long storage life (stored up to 2 years) and could withstand long sea voyages. Malabar gourd is rarely grown in industrialized countries, except as a rootstock onto which cucumber is grafted. However, in Latin America this species is a vegetable called “zambo,” as well as livestock feed. Even fruits of wild plants are collected and eaten (Andres, 1990).

Cultivation areas

Pumpkin is grown in the central regions of the Non-Black Earth zone, Central Black Earth zone, beyond the Urals, and in Siberia.

Yield

Pumpkin yield ranges from 30 t/ha to 80 t/ha.

Chemical composition

Chemical composition of giant pumpkin (Cucurbita maxima), per 100 g fresh weight of edible part (Rahman, A.H.M.M. et al., J. Appl. Sci. Res., 4(5), 555, 2008):

• water — 92.6%;
• proteins — 1.4 g;
• fats — 0.1 g;
• dietary fiber — 0.7 g;
• carbohydrates — 4.6 g;
• energy value — 13 cal.

Vitamins:

• A — 1840 IU;
• thiamine — 0.06 mg;
• riboflavin — 0.04 mg;
• nicotinic acid — 0.5 mg;
• C — 2 mg.

Minerals:

• calcium — 10 mg;
• magnesium — 14 mg;
• phosphorus — 30 mg;
• sodium — 5.6;
• potassium — 139;
• iron — 0.7 mg;
• copper — 0.2 mg;
• sulfur — 16 mg;
• chlorine — 4 mg.

Chemical composition of butternut squash (Cucurbita moschata), per 100 g fresh weight of edible part (Rahman, A.H.M.M. et al., J. Appl. Sci. Res., 4(5), 555, 2008):

• water — 94%;
• proteins — 1 g;
• fats — 0.1 g;
• dietary fiber — 0.7 g;
• carbohydrates — 4.6 g;
• energy value — 21 cal.

Vitamins:

• A — 2000 IU;
• thiamine — 0.04 mg;
• riboflavin — 0.02 mg;
• nicotinic acid — 0.5 mg;
• C — 15 mg.

Minerals:

• calcium — 23 mg;
• iron — 0.3 mg.

Botanical description

Among plants of the genus Pumpkin (Cucurbita) there are five domesticated species:

• Cucurbita argyrosperma. Fruit stalks hard, angular, but at maturity become round, corky, only slightly branched at the point of fruit attachment. Stem hard, angular, grooved. Leaves moderately lobed, softly pubescent. Seeds usually white, can be very large; surface smooth or cracked; margin prominent, smooth or shaggy, sometimes dark.
• Cucurbita ficifolia (fig-leaf gourd). Fruit stalks hard, smooth-angular, with slight swelling. Stem hard, smooth-grooved. Leaves lobed, almost round, slightly prickly. Seeds usually black, sometimes tan; surface often finely dotted; margin smooth and narrow.
• Cucurbita maxima. Fruit stalks generally soft, round, often corky, not flared. Stem soft, round. Leaves usually without lobes, almost round, soft. Seeds white to brown; surface sometimes split or wrinkled; margin very narrow; seed scar oblique.
• Cucurbita moschata. Fruit stalks hard, smooth-angular, pentagonal in cross-section, widely spaced. Stem hard, smooth-grooved. Leaves almost round to moderately lobed, soft. Seeds dull white to brown; surface smooth or somewhat rough; margin noticeable, usually uneven, often dark; seed scar slightly slanted.
• Cucurbita pepo (zucchini). Fruit stalk hard, angular, sometimes slightly swollen directly near the fruit. Stem hard, angular, grooved, prickly. Leaves palmate-lobed, often deeply dissected, prickly. Seeds dull white to tan; surface smooth; margin noticeable but usually smooth; seed scar square or rounded.

And ten wild species (Schaefer and Renner, 2011).

In Russia, the most important pumpkins are:

• common table, or hard-rind, — Cucurbita pepo L.;
• fodder large-fruited — Cucurbita maxima L.;
• butternut — Cucurbita moschata Duch.

Cucurbita ecuadorensis may be an incipient domesticated species that began the domestication process but was then abandoned when Cucurbita maxima was developed. Some accessions of Cucurbita ecuadorensis have relatively large and non-bitter fruits, but this species is no longer cultivated in its center of origin.

Most species, including domesticated ones, are mesophytes; the remaining species are xerophytic perennials. All are sensitive to frost and are long vines with tendrils. However, some varieties, especially Cucurbita pepo, have a compact bush in which tendrils are reduced in size and function.

Root system powerful, taprooted, well developed.

Stem ordinary, prostrate, creeping, branching, cylindrical, hollow.

Large leaves five-lobed, palmate-lobed or almost round, with coarse awl-shaped pubescence. Some varieties of Cucurbita pepo and Cucurbita maxima, as well as many varieties of Cucurbita moschata and Cucurbita argyrosperma, have variegated leaves, with white or silvery areas at the junctions of the main veins.

Varieties

Assortment of winter squash varieties Cucurbita pepo:

(A) Jack-o’-lantern – ornamental pumpkin and pie pumpkin. (B) Spaghetti. (C) Acorn. (D) Delicata. (E) Styrian oilseed. (F) Delicata–acorn.

Different species of Cucurbita are known under the same common name pumpkin.

In foreign practice, pumpkin varieties are usually divided into summer and winter squashes, depending on whether the fruit is used immature or mature. In domestic practice, “summer squashes” correspond to pattypan, zucchini, and marrow, while “winter squashes” — traditional pumpkin.

Winter squashes are usually fine-grained, with a milder taste, and are used for cooking and suitable for winter storage. Winter squashes can be Cucurbita pepo (e.g., acorn, delicata, jack-o’-lantern, Styrian oilseed, and spaghetti types) (Fig.), Cucurbita maxima (hubbard, kabocha, and buttercup types), Cucurbita moschata (butternut), or Cucurbita argyrosperma (e.g., ‘Green Striped Cushaw’). In Cucurbita pepo, bush habit distinguishes most summer squash varieties from winter squash, although an increasing number of small winter and ornamental pumpkins have a bush or semi-bush habit.

Summer squashes are those forms, almost always Cucurbita pepo, that are used immature as a table vegetable, as well as several varieties of Cucurbita moschata and Cucurbita maxima bred for use as summer squashes.

The English term applied to pumpkins, “squash,” comes from the Native American word “asku-tasquash,” meaning eaten raw or uncooked. Another English name for pumpkin, “pumpkin,” comes from the Old English word “pompion,” Greek “pepon,” and Latin “pepo,” which together mean a large, ripe, round melon or pumpkin. Today the term “pumpkin” is used variously and has no botanical meaning. It usually refers to any pumpkins used for food, ornamental, or fodder purposes.

Cultivated ornamental pumpkins Cucurbita pepo, which have small fruits of diverse shapes and colors, are used for decoration.

Distinguishing features of species of the genus Pumpkin

Fruit stalks of four domesticated species of Cucurbita:

(A) Cucurbita pepo (center of domestication in Mississippi River Valley). (B) Cucurbita pepo (Mexican center of domestication). (C) Cucurbita maxima. (D) Cucurbita argyrosperma. (E) Cucurbita moschata. Note that fruit stalks of Cucurbita pepo are hard, star-shaped in cross-section, and do not expand at the base. Fruit stalks of Cucurbita maxima are large, smooth, and spongy. Fruit stalks of Cucurbita argyrosperma are similar to Cucurbita maxima but have hard ridges with spongy tissue filling the depressions. Fruit stalks of Cucurbita moschata are hard, pentagonal in cross-section, and flared at the base.

Species of pumpkin can be distinguished based on characteristics of peduncle, leaves, and seeds. The fruit stalk is especially characteristic for each of the domesticated species (Fig.).

Fodder large-fruited pumpkin (Cucurbita maxima)

Pumpkin ‘Golden Delicious’ of hubbard type Cucurbita maxima, used for processing and culinary seeds.

Some varieties of Cucurbita maxima produce the largest of all pumpkins. At giant pumpkin contests, the winning fruit in 2016 weighed 1,193 kg.

Fodder large-fruited pumpkin is distinguished by a cylindrical, hollow, creeping stem.

Leaves kidney-shaped, slightly notched, with coarse hairs.

Flowers large, orange-yellow.

Fruits spherical, flattened, or elongated, reaching 50–70 cm in diameter, color varied. Flesh loose, juicy, orange, sometimes white, sugar content 4–8%. Fruits of this species can be: orange, green, or gray; smooth or ribbed; smooth or warty; usually round or oval; and sometimes with a protrusion at the flower end. This reaches extreme limits in turban varieties, where about half of the ovary is exposed.

Fruit stalks in Cucurbita maxima varieties are usually large, round in cross-section, and spongy, initially soft but hardening during fruit storage. Although most varieties are used for growing winter squashes, some are eaten as an immature vegetable, and the seeds can be used as food. ‘Golden Delicious’ is a large variety with soft orange rind that is used both for processing flesh into puree and for producing large plump white edible seeds (Fig.).

Seeds large up to 2–3 cm, smooth, with an indistinct rim, white or brown, rough or smooth. Oil content 36–50%. Weight of 1,000 seeds 240–300 g.

Biological features

Pumpkin, unlike melon and watermelon, is less heat-loving and drought-resistant, and also light-loving.

Seeds germinate at 10–13°C. Seedlings are more resistant to low temperatures.

Optimal are loamy, cohesive, fertile soils.

Cultivation practices

Main page: Growing cucurbit crops

General recommendations for pumpkin cultivation practices are similar to recommendations for all cucurbit crops.

Fertilization

Under pumpkin, during deep autumn soil cultivation, 30–40 t/ha of manure is applied. Higher doses can delay fruit ripening and worsen their quality.

Sowing

The optimal time for sowing pumpkin seeds is when soil temperature at a depth of 10 cm is 9–10°C. Seedlings then appear after 6–7 days.

Recommended sowing schemes: 2.5×1.8–2.0 m or 2.8×1.5–1.8 m.

Seeding rate — 3–5 kg/ha (2.3–4.6 thousand/ha seeds). Seed sowing depth — 6–8 cm. 1–2 plants are planted per hill.

Harvesting

Pumpkin harvesting is carried out in one pass before frost. A light frost will not damage ripe fruits and may facilitate harvesting, as it will destroy vines and expose fruits, but prolonged exposure to temperatures below 10°C leads to fruit damage. If fruits can be harvested before heavy precipitation, their storage duration will increase.

When harvesting pumpkin, it is recommended to leave 2–3 cm of peduncle on the fruits for better keeping quality. When directly harvesting into large pallet containers, the peduncle length should be reduced or removed to avoid damaging other fruits.

Ripeness of pumpkin fruits is determined by color and firmness of the rind. In tropical countries, ripe fruits are harvested when the rind loses its gloss.

When harvesting pumpkin, mechanized collection of fruits into windrows using a UP V-8 windrower is economically justified, followed by picking up the windrows with a PBV-1 picker and gently placing them into vehicles. The technology reduces labor costs by 5–8 times compared with harvesting fruits with carrying to the field edge.

Pumpkin fruits are quite diverse in size, shape, and color, so it is difficult to obtain a uniform product from one harvest. Nevertheless, sorting for uniformity of appearance is important to meet market requirements. For selling pumpkin on the domestic market, there are three established size categories (small, medium, and large), based on fruit weight. Small pumpkins weigh from 1.4 to 3.2 kg, medium pumpkins weigh from 3.3 to 5.5 kg, and large pumpkins weigh 5.6 kg or more. Export markets accept fruits of different sizes, although preference is given to large fruits weighing 5.6 to 8 kg. Fruit shape can vary from round, oval to slightly flat. Rind color also varies from green, blue-green to tan. Striped pattern or mottling of the rind also varies, although stripes are usually white or cream. The rind may be smooth or wrinkled.

All fruits should be inspected for external signs of maturity, and only ripe pumpkins should be packed. Fruits should not have noticeable spots on the rind. The rind should not be discolored or have superficial mold growths. Fruits should not have insects or mechanical damage, and any partially decomposed fruits should be rejected. Fruits should have a closed peduncle end and no cracks to avoid serious rotting problems. The flesh should be firm and dark orange, since many pumpkins are sold on the market cut. Randomly selected fruits should sometimes be opened to evaluate internal color.

Intact fruits are suitable for storage. Pumpkins not intended for immediate sale should be stored in a cool, dry, well-ventilated room. The optimal temperature for storing pumpkin is 10–12°C and relative humidity 70–75%. At this temperature, fruits can be stored up to 3 months without significant loss of quality. Storage at ambient temperature will lead to excessive weight loss, loss of surface color intensity, and reduced culinary qualities. Green-skinned varieties at high temperature gradually turn yellow, and the flesh becomes dry and fibrous. The storage life of pumpkin at ambient temperature is limited to several weeks. On the other hand, fruits should not be stored at low temperatures. Pumpkins are susceptible to chilling injury and should never be stored below 10°C.

In warm and dry rooms, fruits can be stored all winter.

Packaging used for selling pumpkin depends on the market destination. Fruits sold on the domestic market and nearby Caribbean export points are usually packed in mesh bags. Bags usually contain three to seven fruits, and their weight is about 23 kg. However, mesh bags provide virtually no protection against bruising and physical injury. Variability in fruit size also leads to problems with bulging of the mesh bag. Smaller pumpkins intended for more distant export markets should be packed in sturdy, well-ventilated cardboard boxes containing 19 kg of fruit. Cardboard boxes should have minimum tear strength, and internal dividers should be used to separate and protect fruits. Large wooden bulk containers holding 360 to 410 kg of fruit can be used for sea transport to export market destinations. Pumpkins packed in cardboard boxes and transported in sea containers should include an additional 5% weight to account for moisture and weight loss from respiration that will occur during transport.

Varieties

Table pumpkin varieties: Almond 35 (1950), Mozoleevskaya 49 (1943), Dietetic, Spanish 73, Kherson, Don Sweet (1985), Marble, Dachnaya (2002), Medicinal (1994), Altai 47 (1955), Gribovskaya Bush (1964), Khutoryanka (1990), Bush Orange (1995), Winter Sweet (1995).

Fodder large-fruited pumpkin varieties: Stofuntovaya (1947), Vitamin, Biryuchekutskaya 27, Large-fruited 1 (1950), Hybrid 72, Ufimskaya (1981).

Butternut pumpkin varieties: Prikubanskaya (1998), Zhemchuzhina (2000).

Breeding

One of the main and relatively recent directions of many squash breeding programs is disease resistance. Compared with other major cucurbit crops, squash is very vulnerable to attacks by viruses, fungi, and bacteria. In addition to traditional plant breeding methods, including interspecific hybridizations to transfer disease resistance alleles from wild Cucurbita species to cultivated ones, virus coat protein genes have been incorporated to provide additional resistance. Seminis (a Bayer subsidiary) released several summer squash varieties (Cucurbita pepo) with resistance to watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV) using virus coat protein. Varieties carrying this trait are usually designated by the symbol “II” or “III” after the variety name.

Breeders continue to improve the flesh quality of winter squashes, including deeper orange color and provitamin A carotene content. Breeding is also conducted for taste, texture, consistency, and absence of bitterness.

Oved Shifriss transferred the bicolor fruit gene (B) from ornamental pumpkin Cucurbita pepo into summer squash. In the genetic background of pumpkin, this allele leads to the formation of bicolored fruits, each fruit on the plant having a variable proportion of green and yellow rind color. Through breeding for B and corresponding modifiers, it was possible to develop summer squash varieties with fully yellow fruits that have high vitamin A content compared with most summer squash varieties. Symptoms of WMV can be masked on these varieties; infected fruits do not develop the unsightly green rings created by the virus on other yellow-fruited squashes, and therefore they can be sold. ‘MultiPik’ and other hybrid varieties with B have become commercially important.

Although bush varieties of Cucurbita pepo (e.g., zucchini) and Cucurbita maxima (e.g., ‘Emerald’) have been cultivated for many years, until recently only a few varieties of Cucurbita moschata with short internodes were available, such as ‘Burpee Butter Bush’. The variety ‘Burpee Butter Bush’ served as a source of semi-bush habit found in varieties ‘El Dorado’ and ‘La Estrella’, developed by the University of Florida in 2002, and ‘Tama Dorada’, developed by the University of Puerto Rico Experiment Station in 2013.

List of sources

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