Many hundreds of varieties and hybrids, both natural and artificial, which come in all shapes, colours, sizes and degrees of pungency make the classification of the domestic Capsicums and most notably that of C. annuum, all the more confusing. Most commercially grown and used capsicums belong to C. annuum, while the other three species are restricted in their occurrence and use and are little known outside the Latin American countries. Capsicum peppers belong to the family Solanaceae and like tomato and aubergine are warm-season, frost-sensitive, tropical perennials grown commercially as annuals, particularly in short-season areas. Fruits of domesticated species are variable in pungency and do not abscise. C. annuum is the most widely cultivated and economically important species and includes both sweet- and pungent-fruited cultivars of various shapes and sizes. Capsaicin is the chemical responsible for fruit pungency. Peppers are established by either direct sowing or transplanting, the latter being the standard method of establishing plants in short-season areas and where expensive F₁ hybrid seed is used. Direct sowing tends to be used for large-scale production of mechanically harvested peppers for processing. Peppers are also widely grown in greenhouses; protected cultivation relies heavily on grafted plants to increase plant vigour, uniformity and disease tolerance. Yields vary widely, from 1.5 to 18 t/ha, depending on cultural practices, growing conditions and cultivars. Harvested bell pepper fruits are largely destined for the fresh market, while drying and processing are used to produce chilli pepper products.

C. annuum is listed as a 'casual alien, cultivation escape, environmental weed, garden thug, naturalized, weed' in the Global Compendium of Weeds (Randall, 2012). The species spreads by seed, which it produces profusely, and it has been transported through human and animal consumption as well as economic trade for hundreds of years (Basu and De, 2003). While the species is not yet reported to be invasive, it is known to be a cultivation escape in Finland and Puerto Rico, and is labelled an agricultural weed in Portugal and western Europe (Liogier and Martorell, 2000; Randall, 2012). It has been widely cultivated around the world as a valuable food and medicinal plant (Basu and De, 2003; FAO EcoCrop, 2014). There have been major concerns of the species in international trade due to the plethora of associated pests and parasites that are unintentionally introduced by the species to non-native habitats (USDA-APHIS, 1996). Further evaluation of the risk of invasiveness for C. annuum is needed.

The genus Capsicum consists of all the ‘chilli pepper plants’, and the confusing terminology ‘chilli’ is often used frequently and interchangeably with other names including ‘chile’, ‘aji’, and ‘paprika’ to refer to multiple species (Basu and De, 2003). The genus name Capsicum derives from a Greek-based derivative of the latin word ‘kapto’, meaning ‘to bite’, in reference to the heat or pungency of the species’ fruit (Basu and De, 2003), although it has also been speculated to derive from the Latin word ‘capsa’, a box, referring to the shape of the fruit in forms of the typical species (Britton, 1918). The common name ‘chile’ is a variation of ‘chil’, derived from the Nahutal (Aztec) dialect (Basu and De, 2003).

The number of global species within the Capsicum genus has long been subject to debate, with various authors ascribing 25 species to the genus, 33 by Morrison in 1680, 27 by Tournefort in 1700, 2 by Linnaeus in 1753, and 5 by Smith and Heiser (Basu and De, 2003). There are presently considered to be five domesticated species of Capsicum from approximately 25 recognised species in the genus, the primary distinguishing characteristics being flower and seed colour, shape of the calyx, number of flowers per node and their orientation; these five species are C. annuum, C. frutescens, C. chinense, C. baccatum and C. pubescens (Hawkes et al., 1979; Basu and De, 2003; Aguilar-Melendez et al., 2009). Cultivated C. annuum is thought to have been domesticated from wild populations of C. annuum var. glabriusculum in Mexico, possibly multiple times from geographically separate wild populations (Aguilar-Melendez et al., 2009).

Capsicum annuum, the genus type species, is often grouped with C. frutescens (chillies, hot or tabasco pepper) as species C. annuum sensu lato. In the literature, the rich variation of C. annuum sensu stricto has mainly been classified according to fruit shape, but there is no satisfactory cultivar group classification. Zhigila et al. (2014) recently described fruit morphology of five varieties of C. annuum. A common grouping of cultivar groups for C. annuum is as follows:

A very variable, normally annual herb or subshrub, 0.5-1.5 m tall, erect, much branched, grown as an annual. Taproot strong, lateral roots numerous. Stem irregularly angular to subterete, up to 1 cm in diameter, much branched, often tomentose near branchings, green to brown-green, often with purplish spots near nodes. Leaves alternate, simple, very variable; petiole up to 10 cm long; leaf-blade ovate, up to 10(-16) cm x 5(-8) cm, acuminate at apex, margin usually entire, subglabrous, light to dark green. Flowers usually borne singly, terminal; pedicel up to 3 cm long in flower, up to 8 cm long in fruit; calyx cup-shaped, persistent and enlarging in fruit, usually with 5 conspicuous teeth; corolla campanulate to rotate with five to seven lobes, 8-15 mm in diameter, usually white; five to seven stamens with pale blue to purplish anthers; ovary 2(-4)-locular, style filiform, white or purplish, stigma capitate. Fruit a non-pulpy berry, very variable in size, shape, colour and degree of pungency, usually more or less conical, up to 30 cm long, green, yellow, cream or purplish when immature, red, orange, yellow, brown when mature. Seed orbicular, flattened, 3-4.5 mm in diameter, approximately 1 mm thick, pale yellow.

The genus Capsicum is of New World origin. It comprises five domesticated and about 25 wild species. Mexico is believed to be the centre of origin of C. annuum, whereas C. frutescens and the other cultivated species (C. baccatum var. pendulum, C. chinense and C. pubescens) originated in South America. Capsicum peppers were introduced to Asia in the sixteenth century by Portuguese and Spanish explorers via trade routes from South America. Widespread geographic distribution of C. annuum and C. frutescens has occurred on all continents, whereas the others are uncommon outside South America.

The species C. annuum is native to the Americas (Acevedo-Rodriguez and Strong, 2012) but its exact origin is uncertain. It has been speculated to originate from a district of Central America (Basu and De, 2003), or to have been domesticated in Mexico (Aguilar-Melendez et al., 2009). It has been suggested by Pickersgill that C. annuum var. glabriusculum in central Mexico is the wild progenitor of cultivated C. annuum var. annuum (Aguilar-Melendez et al., 2009. As one of the first domesticated plants of Mesoamerica, Capsicum has been known since the beginning of civilization in the Western hemisphere and has been part of the human diet since 7500 BC. It was either Christopher Columbus or his accompanying physician Chanca who first reported the use of Capsicum in the Americas around 1493-1494 and certainly Columbus who introduced it to Europe; by the mid-17^th century Capsicum was being cultivated throughout southern and middle Europe as a spice and medicinal drug, with introductions of one species to Japan and five to India (for mass cultivation in the colonies, from the Portuguese) around this time (Basu and De, 2003).

Capsicum had been introduced to Jamaica by 1871, as Macfadyen observed the use of Capsicum fruit by Caribbean natives as a food and drink condiment, but the plant is not mentioned by species (Macfadyen, 1871).

Likewise in Puerto Rico, Bello Espinosa (1881) did not report the species in his Flora of Puerto Rico, although C. baccatum was included. The species was observed in Bermuda by Britton in 1918, who reported it also present in tropical America and cited HB Small that it was “occasionally seen outside of plantations”. The species can now be found across the West Indies, Lesser and Greater Antilles, Puerto Rico, and the Virgin Islands (Acevedo-Rodriguez and Strong, 2012).

In Asia the species had been introduced to the Philippines by 1888 as it was observed on Taal Volcano near the capital-city Manila; by 1888 it also had Japanese and Chinese local names, indicating that its introduction to those countries would have been sometime before 1888 as well (Tenison-Woods, 1888).

C. annuum is listed as a ‘casual alien, cultivation escape, environmental weed, garden thug, naturalized, weed’ in the Global Compendium of Weeds (Randall, 2012). It is known to have escaped cultivation in Finland and is an agricultural weed in western Europe (Randall, 2012). C. annuum possesses invasive traits which could post threat to native flora, including high production of seeds dispersed through human and animal consumption of the fruits, and widespread distribution outside its native range. Risk of introduction for C. annuum has also been reported as very high due to the serious pests associated with the species; these pests are described further in the ‘Natural Enemies’ section. According to a 1996 risk assessment report, because of the serious risk of introducing associated root pests, the species had been rejected for import from Chile to several countries, including Columbia, Honduras, Panama, Chile, Ecuador, Costa Rica, Nicaragua, and Venezuela (USDA-APHIS, 1996). 

C. annuum is spread by movement of seeds, which are produced in large quantities and remain viable for over a year. In the wild, the seeds are distributed primarily by birds; they drop seeds while eating the fruits, or seeds pass through the digestive tract unharmed (Aguilar-Melendez et al., 2009). Chillies are a favorite food of many birds living in the natural range. The species is also intentionally spread by humans for use of its fruits and leaves as a food, spice, ornamental, and medicine (Basu and De, 2003; FAO EcoCrop, 2014). It is known to have unintentionally escaped cultivation in Puerto Rico and Finland (Liogier and Martorell, 2000; Randall, 2012), and can be spread by both biotic and abiotic vectors, as the species can grow in sandy, coastal areas (Vascular Plants of Ecuador, 2014).

C. annuum can grow across a range of dry, sub-arid, sub-humid and humid forests at 0-1000 m altitudes in Madagascar (Madagascar Catalogue, 2014) and in similar forest conditions in Antioquia, Colombia to altitudes of 1500 m (Vascular Plants of Antioquia, 2014);  in Panama in is found at 0-2000 m (Panama Checklist, 2014). In Peru, the species is also found at altitudes of 0-2000 m, in disturbed areas, forests and rocky slopes (Peru Checklist, 2014). The species is cultivated in plains, lower hills and valleys in India, at a wider range of altitudes, 0-2100 m (Basu and De, 2003). In Bolivia the species grows in rain forests, dry valleys, and mountain lowlands, and has been found at varying ranges of altitudes, 0-500, 1000–1500, 2000–2500, 3500–4000 m (Bolivia Checklist, 2014), while in Ecuador, the species grows in a variety of habitats in the Galapagos, Coastal, Andean, and Amazonian regions, at even higher altitudes of up to 3000 m (Vascular Plants of Ecuador, 2014). 

Viruses cause the most serious damage. The most obvious method of control is to use resistant cultivars. Unfortunately, only few cultivars with virus resistances are known. Cucumber mosaic virus (CMV), Chilli veinal mottle virus (ChiVMV), Potato Y virus (PVY) and a complex of the tobamovirus group are the most important in Asia. Anthracnose caused by Colletotrichum spp. is a major problem of ripened fruits and is best controlled by proper crop management to minimize the source of inoculum via seeds or host debris. Partial resistance has been found. Phytophthora blight and crown rot (P. capsici), Cercospora leaf spot (C. capsici), bacterial spot (Xanthomonas vesicatoria) and bacterial wilt (Ralstonia solanacearum) are other important diseases and are best controlled by integrated pest management, including resistant cultivars that may be available. The major pests are thrips (Frankliniella occidentalis), aphids (Myzus persicae), mites, bollworms (Heliothis spp.), and fruit flies (Dacus spp.). As most of these are polyphagous pests, control is difficult. Resistances are not yet available, but field tolerance is observed in some cultivars and landraces. Inappropriate pesticides and over-use of pesticides often augment the pest problems on Capsicum peppers. Integrated crop management is suggested to overcome multiple pest and disease problems.

For peppers to grow optimally, they need a suitable temperature, good nutrition, and the absence of stress factors. Abiotic disorders, which occur in the absence of biological organisms, are associated with plant stress. Some abiotic disorders can be caused by lack of a major nutrient (e.g. nitrogen or potassium) as well as by an excessive abundance of some elements (e.g. aluminium, boron or copper). The symptoms of some abiotic disorders may be similar to those of a biotic disease, and then very careful investigation may be needed to identify the cause of the problem. Air pollution and salt injury are two abiotic disorders that are becoming more prevalent in pepper-growing regions. Some abiotic disorders can be controlled by avoiding extreme temperatures, inferior soils and air pollutants. Various improperly employed agricultural practices may cause damage to pepper plants, including too deep cultivation, the application of too much fertilizer or pesticide, and the application of a chemical at an incorrect time.

C. annuum is susceptible to a large number of pests and diseases. Viruses cause the most serious damage. The most obvious method of control where the plant is grown as a crop is to use resistant cultivars. Unfortunately only few cultivars with virus resistances are known. Cucumber mosaic cucumovirus (CMV), Chilli veinal mottle potyvirus (ChiVMV), Potato Y potyvirus (PVY) and a complex of the tobamovirus group are the most important in Asia. Anthracnose caused by Colletotrichum spp. is a major problem of ripened fruits and is best controlled by proper crop management to minimize the source of inoculum via seeds or host debris. Partial resistance has been found. Phytophthora blight and crown rot (P. capsici), Cercospora leaf-spot (C. capsici), bacterial spot (Xanthomonas vesicatoria) and bacterial wilt (Ralstonia solanacearum) are other important diseases and are best controlled by integrated pest management, including resistant cultivars that may be available. The major pests are thrips (Frankliniella occidentalis), aphids (Myzus persicae), mites, bollworms (Heliothis spp.), and fruit flies (Dacus spp.). As most of these are polyphagous pests, control is difficult. Resistances are not yet available, but field tolerance is observed in some cultivars and landraces. Inappropriate pesticides and over-use of pesticides often augment the pest problems on capsicum peppers. Integrated crop management is suggested to overcome multiple pest and disease problems.

Ceratitis capitata is a serious parasite associated with C. annuum which has caused countries to reject C. annuum for import to several countries in the past (USDA-APHIS, 1996). 

C. annuum has a positive economic and health impact. It is one of the oldest domesticated crops in the Western Hemisphere and is a major ingredient in most global cuisines with reported health benefits; in addition to being the most widely grown spice in the world, the species has also been used for pharmaceuticals, natural colouring agents and cosmetics, as an ornamental plant and as the active ingredient in self defence repellents (Kim et al., 2014). The top 20 pepper-producing countries grew 33.3 million tons of hot pepper in 2011, and within the last decade, world production of hot pepper has increased by 40% (FAO Statistics, 2014; Kim et al., 2014).

Production for home consumption and production for dried fruits constitute a significant part of the production in Asia. China and Mexico have the largest area harvested. Thailand has historically been a major supplier of capsicum peppers in South-East Asia, although its imports tend to exceed exports. Malaysia exports a large volume of fresh peppers to Singapore, but also imports dried peppers from India, China and Korea. Mexico and the USA are major producers in the Americas, and Nigeria and Egypt in Africa. In Europe, Spain, Hungary and Bulgaria are major producers, but Dutch crops under glass now produce as much as Egypt, indicating the high value of this crop.

The species is classified as an agricultural weed and garden thug by the Global Compendium of Weeds (Randall, 2012), indicating its potential threat to the environment and, in agricultural settings, competition with other crops as well as soil contamination and disease by associated root parasites, increasing vulnerability to invasions and infestations.

As a culinary commodity, C. annuum is known, in dried form, as both chilli pepper and paprika (Basu and De, 2003), and fruits are used in salads, are stuffed or baked, added to soups and stews, dried and used as culinary seasoning, or pickled, while leaves make a good spinach dish (FAO EcoCrop, 2014). Capsicum pepper is the most popular and most widely used condiment all over the world. Capsicum peppers are extensively pickled in salt and vinegar. Colour and flavour extracts are used in both the food and feed industries, for example, ginger beer, hot sauces and poultry feed, as well as for some pharmaceutical products. Sweet, non-pungent peppers are widely used in the immature, green-mature or mature-mixed-colours stage as a vegetable, especially in the temperate zones. Capsicum extracts show promise against some crop pests.

In addition to uses as food and food additives, the fruits of C. annuum also have been grown on a large scale and used as medicine for the digestive system, blood system, muscular/skeletal, and skin applications (FAO EcoCrop, 2014). It has also been reportedly used in arrow poisons by some tribal peoples, such as the Dyaks of Borneo and Youri Tabocas of Brazil (De, 1994). The commercial use of the species in skin cosmetic products was recently reviewed in a toxicological risk assessment and found to be safe to humans within the ingredient formulae (Anon, 2007).

Ornamental peppers reach 25 to 50 cm in height and are grown as annuals or pot plants, producing colourful fruits. In warmer climates, ornamental peppers are perennial and a good bedding plant for hot weather conditions, performing well as a ground cover in mixed flower borders, as an edging, or in containers. Most varieties that are bred for ornamental use hold their peppers in a upright position above the foliage.
 

Capsicum peppers are propagated by seed. Seeds should be harvested from mature fresh fruits after 2 weeks of post-harvest ripening. Seeds remain viable for 2-3 years without special conservation methods if kept dry, but they rapidly lose viability if improperly stored at high temperature or humidity. Seed dormancy may occur to a limited extent, especially if seed is harvested from under-ripe fruits. Seed priming treatments are sometimes effective in stimulating germination. Some 200-800 g of seed is required per ha, depending on plant density. In Asia, seeds are usually sown shallow in nursery beds or flats, and transplanted bare-rooted to the field. Seed-beds are usually covered with straw, leaves or protective tunnels. For better production, seedlings should be transferred to seedling pots (plastic pots, paper cups, banana leaf-rolls, etc.) when the cotyledons are fully expanded. In the nursery, starter fertilizer is recommended at 2-week intervals. Transplants are planted out in the field at the 8-10 true leaf stage, usually 30-40 days after sowing. Hardy transplants can be produced by restricting water and removing shade protection, starting 4-7 days before transplanting. Transplanting should be done during cloudy days or in the late afternoon, and should be followed immediately by irrigation. Direct sowing in the field is practised to a limited extent. Plant populations may range from 10,000-130,000 plants per ha, depending on the region, management practices, and cultivar. Capsicum peppers are well adapted to sole cropping and intercropping systems. In Asia, production is usually practised on small-scale farms on plots of 0.1-0.5 ha, although total acreage may be substantial. Capsicum peppers are often relay-cropped with tomatoes, shallots, onions, garlic, okra, Brassica spp. and pulses. They also grow well among newly established perennial crops.

Husbandry

Capsicum peppers thrive best if supplied with liberal quantities of organic matter and a balance of mineral fertilizers. A reasonable recommendation is to supply 10-20 t/ha of organic amendments. General nutrient requirements are 130 kg/ha of N, 80 kg/ha of P and 110 kg/ha of K, split into basal plus side dressings at 3-4-week intervals, beginning at first flowering. Boron at the rate of 10 kg/ha is also recommended. Nutrient availability is subject to soil type and environmental conditions, so local recommendations vary. In Asia, manual weeding is the common practice for weed control. It is most critical at the reproductive phase. Organic or plastic mulches are very effective for weed control, and reflective mulches help to minimize insect vectors of plant viruses. Staking can help minimize lodging. Capsicum peppers may be grown under rainfed or irrigated conditions. To avoid certain diseases, pests or allelopathic damage, Capsicum peppers should not be planted after other solanaceous crops, sweet potato or jute.

Harvesting

Capsicum peppers are ready for harvest 3-6 weeks after flowering depending on the fruit maturity desired. Green fruits are mature when firm; if gently squeezed they make a characteristic popping sound. Harvesting is done by hand or with the aid of a small knife. Sweet Capsicum peppers are often harvested at the green mature stage, although sometimes they are harvested red. Assorted fruit colours such as yellow, orange, chocolate and purple are also available in specialized markets. Hot Capsicum peppers are harvested green or red depending on their utilization. For the fresh market, fruits are harvested mature but firm, whereas capsicum peppers sold as dried pods may be left to partially dry on the plants before harvesting. Capsicum pepper yields vary widely from 1.5-18 t/ha, particularly in Asia. Maximum dry weight recovery of hot capsicum peppers is near 25-30%. Yields under irrigated conditions tend to be higher than for rainfed production, but vary with other management practices. Unless sold for the fresh market, hot capsicum peppers are sun-dried in most of Asia. Sun-drying usually takes place in a vacant field or roadside, on mats or a well-swept area. In the sun, capsicum peppers will dry adequately in 10-20 days, with frequent turning of fruits. Steaming of hot capsicum pepper before being sun-dried is normally practised in southern Thailand. It tends to improve the appearance, making dried fruits look glossy. Marketing is usually conducted from wholesale to retail markets, but there are also many informal marketing channels. Dried Capsicum peppers may be stored for months in wholesale warehouses to supply year-round demands. Fresh fruits can be stored for up to 5 weeks at 4°C and 95% RH.

Harvested pepper fruits are susceptible to mechanical injury and may be easily damaged during shipment. After harvest, fruits for fresh market should be rapidly cooled to about 10°C to remove field heat. They are then washed in ambient or warm water. In some regions, the wash water is chlorinated to reduce postharvest diseases before storage or shipment, although chlorine washes will not reduce disease development in fruit infected prior to harvest. Bell peppers in particular are chilling sensitive, which causes off-flavours, reduced storage life, pitting, decay, discoloration of the seed cavity, and excessive softening. As a general rule, bell peppers should not be stored below 10-13°C for extended periods. Chili peppers are not as chilling sensitive as bell peppers. Chili peppers stored above 7.5°C suffer more water loss, shrivel, colour change and decay. Storage at 7.5°C is considered the best for maximum shelf-life of 3-5 weeks. Chilies can be stored at 5°C for at least 2 weeks without visible signs of injury. Storage at 5°C reduces water loss and shrivel, but after 2–3 weeks, chilling injury is mostly detected as discoloration of the seeds. Ripe or coloured chilies are less chilling sensitive than mature green ones.

Bell peppers derive a slight benefit from controlled and modified atmosphere storage; there are increasing numbers of peppers stored under modified atmospheres for distribution to long-distance markets. Peppers have been classified as a low respiration rate commodity (5-10 ml CO₂ kg h^-1 at 5°C); O₂ levels of 2-5% slow ripening and respiration during transit and storage, and less than 5% CO₂ with optimum conditions of temperature and RH are beneficial for maintaining bell pepper fruit quality. However, little or no improvement has been reported from using controlled atmosphere storage. Levels of CO₂ higher than 5% can cause injury, particularly if peppers are stored below 10°C, inducing calyx discoloration, skin pitting and discoloration, and softening. A 3% O₂ + 5% CO₂ atmosphere is more beneficial for red than green peppers stored at 5-10°C for 3 to 4 weeks. Red peppers also appear to tolerate high CO₂ atmospheres better than green peppers.

In most of Asia, unless sold for the fresh market hot capsicum peppers are sun-dried. Sun-drying usually takes place in a vacant field or roadside, on mats or a well-swept area. In the sun, capsicum peppers will dry adequately in 10-20 days with frequent turning of fruits. Steaming of hot capsicum pepper before being sun-dried is normally practised in southern Thailand. It tends to improve appearance, making dried fruits look glossy. Marketing is usually conducted from wholesale to retail markets, but there are also many informal marketing channels. Dried capsicum peppers may be stored for months in wholesale warehouses to supply year-round demands. Fresh fruits can be stored for up to 5 weeks at 4°C and 95% RH.

Principal sources: Welbaum (2015); Bosland and Votava (2012)

There are more than 20 Capsicum species; however, all of the cultivated varieties belong to five species: C. annuum, C. frutescens, C. chinense, C. baccatum and C. pubescens. C. annuum, the non-pungent form being the one known as bell pepper or sweet pepper, and C. frutescens, also called red pepper, tabasco or chilli, are the main species. In general, it can be said that most of the cultivated C. annuum cultivars taste mild and sweet, and most of the C. frutescens cultivars taste pungent and hot. Sweet peppers are used fresh or dried. Fresh peppers are used as a vegetable or in salads, they can be cooked and used in stews and other dishes, and they are sometimes sliced and pickled. Dried sweet pepper is mostly ground and sold as a powdered product known as paprika, the Hungarian word for Capsicum.

Historically, the large, blocky, four-lobed bell peppers are the most important type grown in the USA and Europe accounting for the largest percentage of commercial fresh market volume. Fruit colours are highly variable: green, yellow or even purple when young and later turning to red, orange, yellow, or a mixture of these colours with advancing age. Green colour is due to chlorophyll, red and purple due to carotenoids, and purple is due to the pigment anthocyanin. As with colour, fruit shapes vary greatly and may be blocky, conical, round, pencil-shaped or combinations. Fruits may also have thick or thin walls and range from 1 cm to more than 30 cm in length and from 1 cm to about 15 cm in diameter.

Examples of bell pepper cultivars for greenhouse cultivation based on mature fruit colour include:

Red: Lorca, Mazurka, Torkal, Triple 4 and Zambra;

Yellow: Bossanova, Fiesta, Kelvin, Neibla, Pekin and Taranto;

Orange: Boogie, Eagle, Emily, Lion and Paramo.

Other types of C. annuum include Cayenne, Banana, Jalapeño, Cherry and Tepin peppers, each with their own distinctive cultivars. Cayenne, named for the city of Cayenne in French Guiana, is also called Guinea spice or the cow-horn pepper because of its elongated curved shape. Cayenne is a red, hot chili pepper that is often dried and made into powder for flavouring and for medicinal purposes, e.g. cv. Long Red Cayenne.

Banana pepper, with a shape and immature colour similar to a banana, is an elongated type of ‘wax’ pepper that turns red at maturity. Wax pepper is a general term for any cultivar that produces yellow fruit. Wax peppers may be either pungent or sweet. For some cultivars, yellow is the immature colour but for others it may be the mature colour. Cultivars of banana peppers can be either mild or slightly pungent (0–500 Scoville units). They are often processed by pickling, e.g. cultivars Hungarian and Anaheim.

Jalapeño peppers are bullet-shaped, 5–9 cm long, very dark green when immature, red at maturity, and somewhat pungent. The name is derived from Xalapa in Veracruz, Mexico where it is traditionally grown. Jalapeños have a wide range of uses including fresh, grilling, baking, stuffing and processing into green sauce. Mild cultivars, such as TAM Mild Jalapeno II, have been developed for the distinctive flavour without the pungency.

Cherry peppers, named for their resemblance to the tree fruit, are green when immature, turning intense red at maturity. Cherry peppers are small and round and may be pungent or sweet depending on the cultivar. They are consumed fresh or pickled in vinegar.

Tepin, also called chiltepin, chiltepe or chile tepin, is the botanical variety glabriusculum of C. annuum that is native to southern North America and northern South America. The name tepin is derived from a Nahuatl word meaning “flea”. The plant is a shrub that attains a height of approximately 1 m, but sometimes reaches 3 m. The tiny fruits are extremely pungent, red to orange-red, round or slightly ellipsoidal, and about 0.8 cm in diameter. When tepin fruits are dried for preserving, they become round even if they were slightly ellipsoidal when fresh.

Some cultivars have been developed to be grown as ornamentals, for their unusual fruit shapes and their wide range of fruit colours.

Principal sources: Russo (2012); Welbaum (2015); Elzebroek and Wind (2008)

Grafting is a common practice in Asian countries (China, Korea, Japan, Taiwan) and the Mediterranean area (Spain, Italy, Israel, Tunisia, Turkey). The protected cultivation of pepper relies heavily on grafted plants in many parts of the world. However, the demand for grafted transplants is anticipated to increase worldwide due to loss of methyl bromide fumigant and the adoption of more sustainable production practices. The primary reason for grafting pepper scions on special rootstocks is to increase plant vigour, uniformity and disease tolerance. Several commercial pepper rootstocks show resistance to major soilborne pathogens such as Phytophthora capsici, Verticillium dahliae, Fusarium oxysporum and Meloidogyne spp. In addition, grafted plants may have higher tolerance to abiotic stresses such as salinity, root hypoxia and extreme temperatures. Cleft, approach, micro- and tube grafting are all techniques that can reliably join pepper scions with compatible rootstocks. Unlike some other species where dissimilar rootstocks give the best performance, pepper scions are most compatible with rootstocks from the same genus. In Taiwan, several lines of C. baccatum, C. frutescens and C. chacoense were identified as suitable rootstocks for sweet pepper production during hot-wet (summer) and hot-dry (autumn) seasons.

Principal sources: Welbaum (2015)

Capsaicin, an odourless, colourless and flavourless chemical, is responsible for the pungency in peppers. Capsaicin stimulates chemoreceptor nerve endings in the skin and especially mucous membranes. Human taste buds can detect as little capsaicin as 10 ppm. A single drop diluted in 100,000 drops of water will produce a persistent burning of the tongue. Biting into a pepper stimulates nerve receptors in the mouth, sending a pain signal to the brain, inducing sweating, salivation and gastric flow in an attempt to rid the body of the irritation. Capsaicin is a stable alkaloid (C₁₈H₂₇NO₃). Scoville heat units (SHU) indicate the amount of capsaicin present in peppers and are therefore a quantitation of the spicy heat or pungency; the greater number of SHU the more pungent a pepper will taste. Purified capsaicin has its own commercial uses. It induces a warm feeling when applied in concentrated form to the skin and is used medicinally in sore-muscle remedies. It is also used to give the “bite” to some commercial ginger ale brands and is the powerful irritant in some “pepper” sprays.

Bell pepper is the only Capsicum not to produce capsaicin. Red bell peppers are, however, one of the very best sources of vitamin A. Vitamin A content increases dramatically as the fruits ripen and turn red. Vitamin C and sugar content increase with colour change as well. Cultivars that turn yellow when mature do not contain as much vitamin A as red peppers.

As Capsicum consumption is increasing, it may represent an important source of vitamins for world populations. The antioxidant vitamins C and E and provitamin A are present in high concentrations in various pepper types. Peppers are also good sources of carotenoids and xanthophylls and may contain high amounts of vitamins P (citrin), B₁ (thiamine), B₂ (riboflavin) and B₃ (niacin). Peppers are richer in vitamins C and A than the usually recommended food sources. Considerable research has focused on antioxidants in foods, as protection against cancer, anaemia, diabetes and cardiovascular diseases. As an excellent source of these antioxidants, which counter the oxidation of lipids via scavenging oxygen free radicals, a great deal of attention has been paid to peppers. One medium green bell pepper (weighing 148 g) has 30 calories, 7 g total carbohydrates (i.e. 2% of the recommended daily allowance (RDA) for adults), 2 g dietary fibre (8% of the adult RDA), 4 g sugar and 1 g protein, plus, respectively, 8%, 180% 2%, and 2% of the adult RDA for vitamin A, vitamin C, calcium and iron.

Principal sources: Welbaum (2015); Bosland and Votava (2012)

Sudan I, II, III and IV are non-ionic, fat-soluble dyes used as additives in gasoline, grease, oils and plastics and are classified by IARC as Category 3 carcinogens. Chemically the Sudan colours belong to the azo dyes, a class of synthetic organic colorants. Their widespread usage is due to their colourfastness and low price. However, azo colorants are biologically active through their metabolites and have in general been associated with increased occurrence of bladder cancer. In 2004, UK food inspections found that a number of food products such as Worcestershire sauce contained Sudan colours. This was traced back to chillies and chilli products imported from India, chillies making up a part of the recipe of this traditional English product. Further investigations disclosed that the chilli products had had Sudan III added to improve their colour. A subsequent investigation showed that a number of products on the shelves in Europe had contents of Sudan III; these were withdrawn from the market. The addition of Sudan III was at that time not illegal in the countries where the chilli products were produced.

Principal sources: Brimer (2011)

World production of chillies and green peppers in 2013 was estimated by FAO at about 31.1 million tonnes, with Asia producing 68.6% of this total. Production for home consumption and production for dried fruits constitute a significant part of the production in Asia. 

The top five producers were mainland China (15.8 million tonnes), Mexico (2.3 million tonnes), Turkey (2.2 million tonnes), Indonesia (1.7 million tonnes) and Spain (1 million tonnes).

Thailand has historically been a major supplier of Capsicum peppers in South-East Asia, although its imports tend to exceed exports. Malaysia exports a large volume of fresh peppers to Singapore, but also imports dried peppers from India, China and Korea. Mexico and the USA are major producers in the Americas, and Nigeria and Egypt in Africa. In Europe, Spain, Hungary and Bulgaria are major producers, but Dutch crops under glass now produce as much as Egypt, indicating the high value of this crop.

For current information on crop production, see FAO Statistics.

Further research of the species is recommended to evaluate the extent of its invasiveness, especially considering its widespread distribution range and popularity as a food, medicinal and ornamental plant. 

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