Capsicum annuum (PROTA)

Capsicum annuum L.

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Fruit
Vegetable
Dye / tannin
Medicinal
Ornamental
Food security

Protologue: Sp. pl. 1: 188 (1753).

Family: Solanaceae

Chromosome number: 2n = 24

Synonyms

Capsicum frutescens L. (1753), Capsicum chinense Jacq. (1776).

Vernacular names

Capsicum, capsicum pepper; chilli, sweet pepper, bell pepper; bird pepper; chinense pepper, aromatic pepper, bonnet pepper (En). Piment; poivron, paprika; piment oiseau ; poivre de Cayenne; habanero, piment antillais (Fr). Pimentos; pimentão, pimento doce; jindungu, pimento, piri-piri, pimento de caiena; pimento chinês (Po). Mpilipili, mpilipili hoho (Sw).

Origin and geographic distribution

The genus Capsicum originated in Central and South America. The approximately 25 wild species all occur in this area. The cultivated forms were domesticated in prehistoric times; the main difference with the wild types is that the fruits are not easily dehiscent and hence less damaged by birds. Mexico was probably the centre of origin of the chilli and sweet pepper (Capsicum annuum in the narrow sense), while aromatic hot pepper (Capsicum chinense) originated in the Amazonian region and bird pepper (Capsicum frutescens) in the coastal regions of the southern part of tropical South America. In cultivation the 3 species have been crossed intensively and many intermediate forms occur. They are therefore treated here as one broad group of cultivars, although characteristic examples of the 3 original species can still be recognized. Shortly after Columbus’ discovery of America, the Spanish and Portuguese brought capsicum pepper (hot and sweet) to Europe, from where especially the hot pepper was widely dispersed to all tropical and subtropical areas of the world. By the end of the 17^th century it was grown as a popular vegetable and spice everywhere in the tropics and many very distinct types and landraces had been developed. The aromatic hot pepper was probably introduced in West Africa during a later period than the chilli and bird pepper, and African slaves brought it back from West Africa to the Caribbean and West Indies.

Capsicum annuum is cultivated so widely in Africa that African people consider hot pepper as a traditional African vegetable or spice, while the much less popular sweet pepper is seen as an exotic, newly introduced European vegetable. Sweet pepper, one of the most important glasshouse and summer vegetables in Western industrialised countries, is more adapted to temperate climates than hot pepper. Some hot pepper cultivars, including aromatic hot pepper, are adapted to a temperate climate, but the growth of bird pepper is too slow for outdoor cultivation in a temperate climate.

Two other domesticated species, Capsicum baccatum L. (aji) and Capsicum pubescens Ruiz & Pav. (rocoto), are commonly cultivated in Latin America. Commercial cultivars of Capsicum baccatum are occasionally found in Asian countries, whereas adapted cultivars of the rather cold-resistant Capsicum pubescens are extensively cultivated in highland regions of Java (Indonesia), but neither species has been recorded for Africa.

Uses

Capsicum fruits are consumed in fresh, dried or processed form. Non-pungent fruits, usually called sweet pepper, are eaten raw in salads, but more commonly cooked, fried or processed together with other foods. They are consumed in such quantity per serving that they constitute a real table vegetable contributing to the nutritional value of the meal. The most pungent types, including chillies, bird pepper and aromatic hot pepper, are consumed in very small quantities and are considered a condiment or spice for seasoning and stimulating appetite. As many intermediate forms exist, there is no strict borderline between the use of capsicum as spice and vegetable. Hot pepper is processed into ketchup or spice mixtures for flavouring all kinds of food. In Ethiopia dried hot pepper is a component of a mixed spice powder. Hot peppers are extensively pickled in salt and vinegar. In some regions (e.g. Sudan) they are used to make hot fresh sauces by crushing the green immature fruits or cutting them into small pieces and mix them with lime juice, salt and peanut butter. They are used industrially as an ingredient of many products, e.g. hot sauces, canned fish, ginger beer, as well as for some pharmaceutical products. In some regions (e.g. Gabon) shoot tips and young leaves are eaten as a vegetable. The red pigment extracted from ripe fruits is used as a natural colouring agent for food and cosmetics.

Hot pepper is widely used in local medicine. Pungent peppers cause strong salivation, aid digestion and are laxative. Capsaicin, the active ingredient, stimulates the mucous membrane of the mouth, stomach and bowels, causing strong peristalsis. Another effect is sweating of the body, which is a relief in hot climates as it has a cooling effect. It also causes tingling of the tongue and cheeks and secretion of nose, eyes and sinuses. People suffering from a flu experience relief by consuming hot pepper. It is said that regular consumption is beneficial for vascular conditions and against haemorrhoids, varicose veins, anorexia and liver congestion. An infusion of mature fruits is said to stop vomiting, and is used to treat dysentery, fever and yaws. In Ethiopia people consume hot pepper with raw meat, believing that the hot pepper kills dangerous pathogens. Hot pepper has often been ascribed antibiotic properties. It is recommended for people suffering from amoeba infection and intestinal worms. In pure or processed form it is applied externally as a rubefacient and analgesic in cases of back-pain, rheumatism, articular and muscular pains and swollen feet, and antidote in cases of poisoning. The leaves are used as a dressing for wounds and sores, and the leaf sap is squeezed into the eyes against headache (Ghana, Congo). The leaves are prepared as a potion to treat coughs and heart-pain. In East Africa the leaves are externally used against bubonic plague. In Gabon a leaf macerate with lemon juice is dropped into weeping ears. In Guinea a mixture including red pepper powder is used as a traditional insecticide to control kola weevil. Especially in Western countries bushy erect capsicum types with many small red or yellow fruits are popular as ornamental potplants. In recent years hot pepper is increasingly used in aerosol sprays replacing tear gas, for personal defence of police officials. Bird peppers specifically grown for this purpose in Kenya and Tanzania are exported in powder form to the United States.

Production and international trade

FAO statistics estimate world production of capsicum peppers in 2001 at 21.3 million t from a harvested area of 1.6 million ha (average yield 13.4 t/ha); China is the largest producer with 10 million t, followed by Mexico (1.9 million t) and Turkey (1.5 million t). India is probably erroneously represented with only 50,000 t. Production in tropical Africa is estimated at 1 million t, with Nigeria (715,000 t from 90,000 ha) and Ghana (270,000 t from 75,000 ha) as the largest producers. The FAO statistics, however, are incomplete or unreliable for African countries; production from intercropping and home gardens is often not included. Data are presented for only 13 out of the 47 countries of tropical Africa.

Hot peppers, fresh, dried or processed, are an important product in all local markets in Africa, more so in West Africa than in East Africa. In West Africa aromatic hot pepper (Capsicum chinense) is very popular, especially the most aromatic and less pungent cultivars. International trading of fresh or dried hot pepper occasionally occurs, but few data are available. Export from Africa (mainly dried hot pepper) is very limited, e.g. Ethiopia exports to Europe and the Middle East, Nigeria to the United Kingdom, Senegal to France. Ethiopia, Malawi, Zambia and Zimbabwe export oleoresin capsicum (pungent) and oleoresin paprika (not pungent) as food additives and colouring. Fresh hot pepper (mainly aromatic hot pepper) is exported from Uganda and West Africa to Europe (Paris, London, Brussels), mainly during winter months.

The cultivated area of sweet pepper in Africa is much smaller than that of hot pepper. Sweet pepper is becoming increasingly popular as an exotic vegetable, traded through supermarkets. Some sweet pepper is produced in Senegal and Côte d’Ivoire for export to France.

Properties

The approximate composition of fresh hot peppers per 100 g edible portion is: water 74 g, energy 395 kJ (94 kcal), protein 4.1 g, fat 2.3 g, carbohydrate 18 g, fibre 6.0 g, Ca 58 mg, P 101 mg, Fe 2.9 mg, β-carotene 7,140 μg, thiamin 0.25 mg, riboflavin 0.20 mg, niacin 2.4 mg and ascorbic acid 121 mg. The composition of dried hot peppers is given as: water 10 g, energy 1453 kJ (346 kcal), protein 12.5 g, fat 11.5 g, carbohydrate 61.5 g, fibre 23.3 g, Ca 187 mg, P 330 mg, Fe 16.7 mg, β-carotene 14,300 μg, thiamin 0.38 mg, riboflavin 0.68 mg, niacin 7.2 mg and ascorbic acid 12 mg. Fresh green sweet peppers contain per 100 g edible portion: water 86 g, energy 202 kJ (48 kcal), protein 2.0 g, fat 0.8 g, carbohydrate 10.3 g, fibre 2.6 g, Ca 29 mg, P 61 mg, Fe 2.6 mg, β-carotene 180 μg (red, mature fruits 2,760 μg), thiamin 0.12 mg, riboflavin 0.15 mg, niacin 2.2 mg and ascorbic acid 140 mg (Leung, W.-T.W., Busson, F. & Jardin, C., 1968). The content of ascorbic acid (vitamin C) in fresh capsicum and of vitamin A in mature red capsicum peppers is very high. Drying causes a considerable loss of carotene and thiamin, whereas vitamin C disappears almost completely. Differences in cultivar or in ecological and cultural conditions, harvest stage and post-harvest handling are responsible for a large variation in moisture content and chemical composition.

The pungent principle of hot pepper is capsaicin, a complex of capsaicinoid alkaloids found in variable quantities (0.01–1.0% of dry weight) concentrated in the placental tissue and cross-walls of the fruits, but in very pungent types in all fleshy parts. Capsaicin (C₁₈H₂₇NO₃) is odourless, colourless and flavourless. The heat sensation results from irritation of pain receptor cells and differs between individual persons. The content of capsaicinoids can be determined chemically, but in practice (e.g. for testing varieties or differences between samples) the organoleptic method is more practical, using a dilution of one part per million. Referring to pungency three main categories of capsicum fruits are distinguished: (1) non-pungent sweet peppers, (2) moderately pungent or ‘normal’ hot peppers, and (3) very pungent hot pepper types, mostly bird pepper and aromatic hot pepper. However, several cultivars are intermediate. Taste and flavour of peppers depend on other compounds. Glucose and fructose sugars give the sweetness to sweet pepper. A volatile compound, 2-methoxy-3-isobutyl-pyrazine (C₉H₁₄N₂O), causes the typical taste and smell of sweet pepper. Capsicum fruits contain more than 100 compounds contributing to flavour and aroma. The flavour of the aromatic hot pepper is quite different from common hot pepper or bird pepper. Mature fruits are rich in pigments such as carotenoids and xanthophylls, the major pigment being the carotenoids called capsanthin (C₄₀H₅₆O₃) and capsorubin (C₄₀H₅₆O₄)(E 160c).

Capsaicin showed anti-oxidant, antimutagenic, anticarcinogenic and immunosuppressive activities. It also inhibits bacterial growth and platelet aggregation. Hypocholesterolaemic effects have been recorded for the oleoresin. In a double-blind, placebo-controlled clinical test using 30 patients with functional dyspepsia capsicum powder was effective in decreasing the intensity of dyspeptic symptoms, capsaicin being the active ingredient.

The weight of seed, largely depending on cultivar, may be considerable, normally 10–20% of the dry weight of the fruit. The smaller the fruit, the higher the weight percentage of seed, reaching 50% in small dried hot peppers. The seed contains 12–25% oil, mainly composed of linoleic acid, an unsaturated fatty acid, and further mainly of carbohydrates, proteins and fibre.

Adulterations and substitutes

As a spice, hot pepper may be replaced by Aframomum melegueta (Roscoe) K.Schum.

Description

Erect herb or subshrub, up to 2.5 m tall, much-branched, grown as an annual but in home gardens sometimes a short-term perennial; taproot strong, lateral roots numerous; stem irregularly angular to subterete, up to 1 cm in diameter, green to brown-green, often softly hairy and with purplish spots near nodes. Leaves alternate, simple, very variable; stipules absent; petiole up to 10 cm long; blade ovate, up to 10(–16) cm × 5(–8) cm, acuminate at apex, margin usually entire, almost glabrous, pale to dark green. Flowers usually solitary, sometimes 2 or more per node, terminal, bisexual, usually 5-merous; pedicel up to 3 cm long, but elongating up to 8 cm in fruit, usually pending; calyx cup-shaped, persistent and enlarging in fruit, usually with conspicuous teeth; corolla campanulate to rotate, 8–15 mm in diameter, white or greenish, rarely purple, tube short, lobes ovate; stamens adnate at base to corolla tube, with pale blue to purplish anthers; ovary superior, 2(–4)-celled, style filiform, white or purplish, stigma capitate. Fruit a 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 or brown when mature, many-seeded. Seeds orbicular, flattened, 3–5.5 mm in diameter, pale yellow. Seedling with epigeal germination.

Other botanical information

Capsicum annuum, Capsicum frutescens and Capsicum chinense are mostly considered as three different species, based on a combination of fruit and flower characters. They are, however, closely related and it is doubtful whether the distinction is taxonomically justified as it is based on only a few overlapping morphological characters. Many intermediate forms occur, which are difficult to identify and assign to one of the three. Apparently there has been a gene flow between these taxa, and it is likely that they share a common ancestral gene pool. Also DNA finger printing and gene mapping point to a close relation of the three taxa, with clusters of similar genes within each taxon. A certain degree of crossability under field conditions exists. Cytogenetic studies show aberrant chromosome pairing between Capsicum chinense and the two other taxa, yet hand crosses often result in viable and fertile hybrids. At present more and more commercial cultivars are released that have resulted from crosses between these three taxa.

Since for capsicum research in tropical Africa the distinction of Capsicum annuum, Capsicum chinense and Capsicum frutescens on species level is unpractical and unfeasible, they are treated here as belonging to a single species Capsicum annuum. They can, however, be distinguished as cultivar-groups. In the past several horticultural cultivar groupings for capsicum based on fruit shapes have been made. These groups are overlapping and refer mainly to the American situation. For tropical Africa the cultivars can be classified in the following 4 types:

– Sweet pepper (also named paprika, bell pepper); fast-growing annual herb, flowers solitary, white, pending, fruits large, 3–12 cm in diameter, inflated, red, orange, yellow, purple, white, blue or brown when mature, with mild, sweet aroma and taste. Sweet pepper is not very common in Africa, but increasingly important in urban markets.

– Chilli (also spelled chili); fast-growing annual herb, flowers solitary, white, pending, fruits variable, but mostly elongate or ovoid, 2–16 cm long, or globose, mostly red, sometimes orange or yellow at maturity, fruit wall smooth or slightly wrinkled, taste mild to very pungent. This is the most common hot pepper type, for fresh consumption or for drying.

– Bird pepper (Capsicum frutescens); slow-growing short-term perennial or perennial subshrub, flowers in clusters of 2 or more, waxy greenish white, usually erect, fruits elongate, usually upright, usually small and narrow, up to 5 cm × 1 cm, green to cream or yellow when immature, orange to red when mature, fruit wall smooth, extremely pungent. Bird pepper is very common in fields for home consumption, but it is less popular than chillies as a commercial crop because of high labour costs.

– Aromatic pepper (Capsicum chinense also named chinense pepper); fairly slow-growing annual to perennial herb, flowers in clusters of 2 or more, sometimes solitary, waxy greenish (rarely white or purple), usually pending, fruits usually globose to cylindrical, 2–5 cm × 1.5–3 cm, wrinkled, usually pending, red to orange or yellow when mature. Aromatic pepper has a typical flavour and aroma and its pungency can range from extremely hot to very mild. Aromatic hot pepper is fairly common in West Africa, preferred by farmers during the rainy season because it is stronger and more resistant to anthracnose and viruses than chillies.

Most of the numerous African cultivars and landraces can be categorized into these 4 categories, but some are intermediary. Practically all farmers use local cultivars, appropriate for the local market. African countries use their own classification of local cultivars, e.g. the Sudanese classification of the local hot peppers into two groups: ‘Gabaniet’ with small and very hot fruits, and ‘Zalengi’ with medium- and big-sized fruits that are usually mildly pungent. Popular chilli cultivars in Ethiopia are ‘Santaka’, ‘Bakolocal’ and ‘Marekofana’, in Nigeria ‘Dan Mayere’ and ‘Dan Tsiga’. Although international cultivars of chillies (‘Anaheim’), bird pepper (‘Tabasco’, ‘Cayenne’) and aromatic hot pepper (‘Habanero’, ‘Scotch Bonnet’) appear in the market, they are less adapted to the ecological and market requirements of African countries. This situation is different for sweet peppers, for which few, if any, African cultivars exist. Farmers use imported seed, mostly F₁ hybrids, from international seed companies. Some well-known cultivars are ‘Yolo Wonder’, ‘California Wonder’ and ‘Bell Boy’. Farmers growing oleoresin paprika use South African cultivars.

Growth and development

Seeds germinate 6–21 days after sowing. Continuous flowering starts 60–90 days after sowing. Flowers open 3 hours after sunrise and are open for 1–3 days. Although normally self-pollinated, 2–90% cross-pollination may occur, depending on activity of bees and thrips collecting nectar and pollen; on average, cross-pollination is about 15%. Certain cultivars show strong heterostyly causing a high level of cross-pollination. In the bud stage the stigma is receptive, but the pollen is not yet mature, so hand pollination is easy. Under normal circumstances 40–50% of the flowers set fruit. Fruits begin to mature 4–5 weeks after flowering, and can be picked every 5–7 days. The peak harvest period is 4–7 months after sowing. In the absence of frost and diseases growth continues and plants may become perennial.

Ecology

Capsicum annuum is a tropical species, but adapted to cultivation in temperate regions during the summer or, in protected cultivation, year-round. Optimal temperatures for growth and production are between 18°C and 30°C. Seeds germinate best at 25–30°C. Flowering is delayed if day temperatures drop below 25°C. Flower buds abort if night temperatures are too high (above 32°C). Pollen viability is significantly reduced at temperatures above 30°C and below 15°C. Cool nights down to 15°C favour fruit setting. Sweet pepper needs cooler nights and is clearly more adapted to cooler growing conditions than hot peppers. Sweet pepper cultivation is difficult in the hot and humid tropical lowland. Capsicum is day-neutral, but certain forms may show a photoperiodic reaction; long days may slightly delay the first flowering. It tolerates shade up to 45% of solar radiation, although shade may delay flowering. Capsicum grows at a wide range of altitudes, from lowland up to 2000 m, in Ethiopia even up to 3000 m. If not irrigated, an annual rainfall of at least 600 mm is required. Capsicum grows on almost all soil types, but is most suited to well-drained sandy or loamy soils, rich in lime, with a pH of 5.5–6.8 and a high water retention capacity. Severe flooding or drought is injurious. Waterlogging causes poor fruit setting, diseases and fruit rotting. Capsicum is moderately sensitive to soil salinity.

Propagation and planting

Seeds should be harvested from mature fruits after some weeks of post-harvest ripening. Seed extraction of pungent peppers is an unpleasant work that can be alleviated by mechanical dust collection. The 1000-seed weight is about 3.3 g for bird pepper to 7 g for types with large fruits. Seed remains viable for 2–3 years without special conservation methods if kept dry at room temperature, but it rapidly loses viability if stored at high temperatures or humidity. Seed dormancy may occur to a limited extent during some months after harvest, especially if seed is harvested from immature fruits. Seed priming treatments are sometimes effective in invigorating germination and are sometimes applied for sweet peppers in Western countries but they are not used in Africa. Storage of primed (pre-germinated) seed is difficult. To plant one ha, 200–800 g of seed is needed, depending on plant density and provided adequate nursery technology is applied. In fact, the better the seed quality and nursery technology, the lower the seed requirement. The extreme is shown by sweet pepper under protected cultivation; growers use only 150 g/ha of expensive hybrid seed. The hot pepper seed used by most African farmers is from own production or is cheap seed of uncertain quality and origin from local seed dealers. The germination capacity being doubtful, farmers use several kg seed per ha.

The seed is sown shallowly in nursery beds or flats, broadcast or in rows 20 cm apart. Direct seeding is rarely practised. Seedbeds should be protected against rain and direct sun. They are usually covered with straw, palm leaves or plastic. For better production, seedlings may be transferred to seedling pots (soil blocks, plastic pots, paper cups, banana leaf-rolls) when the cotyledons are fully expanded. In the nursery, starter fertilizer is recommended at 2-week intervals. Transplants are planted out in the field when they have 8–10 leaves, usually 30–40 days after sowing. Restriction of watering and removal of shade protection, starting a week before transplanting, is recommended to produce hardy transplants. Transplanting should be done during cloudy days or in the late afternoon; when planted in dry soil irrigation should be applied. Capsicum is suitable for intercropping and is then sometimes sown directly in the field. A normal spacing is 50–80 cm between the rows and 20–40 cm in the rows, with densities of 50,000–80,000 plants per ha. In Ethiopia, farmers transplant in beds 1.2 m wide without rows, at a density of 5–15 plants per m² with an optimum of 10 plants/m². In Mauritius, a spacing of 60 cm × 30 cm (55,000 pl/ha) gave the highest yield (6.2 t/ha); in Zimbabwe, the recommended number of plants per ha is 30,000–55,000 for chillies, 20,000–55,000 for sweet peppers, and 55,000–70,000 for paprika powder production.

Management

In Africa capsicum production is usually practised on small-scale farms on plots of 0.1–0.5 ha. If properly managed, it is labour intensive, especially planting, weed control and the repeated harvests. The greatest part of the hot pepper area in tropical Africa, however, is cultivated in an extensive way as a low input system. Capsicum thrives best if supplied with liberal quantities of organic matter supplemented with balanced mineral fertilizers. Nutrient availability is subject to soil type and environmental conditions, so local recommendations for fertilizer application vary greatly. A reasonable recommendation is to supply 10–20 t/ha of organic fertilizer (e.g. manure). General nutrient requirements are 130 kg/ha of N, 80 kg/ha of P and 110 kg/ha of K, split into a basal dressing plus some side dressings at intervals of 3–4 weeks, beginning at first flowering. Boron at the rate of 10 kg/ha is also recommended. Capsicum is very sensitive to blossom-end rot caused by calcium deficiency and irregular irrigation.

Capsicum is grown under rainfed (rainy season) or irrigated (dry season) conditions; it requires at least 600 mm water during its growing period. During flowering and fruit setting it is sensitive to moisture stress, causing flower and fruit dropping, and more than normal pungency of the fruits. Irrigation is needed when plants show wilting in the afternoon.

In Africa, manual weeding is the common practice for weed control. Organic (usually straw) or plastic mulches are also effective. Staking is not common in most of Africa, but may help to minimize lodging and fruit rotting in the rainy season.

Capsicum is often relay-cropped with tomatoes, onions, garlic, okra, Brassica species, cucurbits and pulses. It also grows well among newly established perennial crops. To avoid soilborne diseases, capsicum should not be planted after other solanaceous crops.

Protected cultivation using plastic tunnels is rarely used in Africa; it is practised for sweet pepper in the highlands, and at lower elevations on seedbeds as roofing against heavy rains.

Diseases and pests

Capsicum suffers from numerous diseases and pests. Many sweet pepper producers in Western countries use integrated pest management (IPM) technology, especially in greenhouses, to keep the crop healthy with a minimum application of toxic chemicals. Many kinds of biological products or natural enemies for the control of capsicum diseases and pests are available, but these are less appropriate for tropical African conditions. Because of the high costs, the majority of the capsicum producers in Africa do not apply chemical spraying. However, the combination of intercropping and refraining from using pesticides maintains a high population density of natural predators of pests and a low infection level. Consequently, crop losses are generally within reasonable proportions. A crop will be more healthy if the farmer uses healthy seed and respects a crop rotation with at least two years without any solanaceous crop to minimize soilborne diseases, applies proper plant spacing for good ventilation against foliar diseases, and good drainage (raised beds in the rainy season). With the intensification of the cropping system, e.g. high doses of fertilizer, the potential yield will rise considerably, but so will the risk of high crop losses. The first control method is to choose a local cultivar with resistance to the most important diseases and pests. However, in tropical African countries improved local cultivars with resistance genes are rarely available. A broad general field tolerance is observed in some landraces.

The most troublesome diseases and pests, reported for tropical Africa, are:

– Virus diseases. Aphid-transmitted viruses are cucumber mosaic virus (CMV), alfalfa mosaic virus (AMV), pepper veinal mottle virus (PVMV), potato virus Y (PVY), pepper mottle virus (PeMV) and a complex of tobamoviruses. Mechanically transmitted viruses are tobacco mosaic virus (TMV) and pepper leaf curl virus (PLCV). Geminiviruses are transmitted by white flies, tomato spotted wilt virus (TSWV) by thrips. Resistance to most viruses occurring in Nigeria was found in local as well as imported hot and sweet pepper accessions; hence prospects for breeding cultivars combining resistance genes are hopeful. Chinense pepper is a source of virus resistance. Reflective aluminium-coated plastic mulches minimize insect vectors (aphids, thrips); this has become common practice in South-East Asia. Mineral oil spraying can be applied against aphids. Several viruses, e.g. TMV, are seedborne; hence the need for healthy seed.

– Fungal diseases. Anthracnose or fruit rot caused by Colletotrichum gloeosporioides and–to a lesser degree– Colletotrichum capsici is a major problem of ripe fruits especially in humid lowland, causing crop losses of up to 90%. Proper crop management to minimize the source of inoculum via seeds or host debris is the best control. Local West African aromatic pepper cultivars are fairly resistant. Cercospora leaf spot (Cercospora capsici) and velvet spot (Cercospora unamunoi) may cause complete defoliation. A major problem in the rainy season, affecting all plant parts, is Phytophthora blight. It is also called crown rot or basal stem rot and is caused by Phytophthora capsici. The Nigerian hot pepper ‘U-Kimba’ is resistant. Damping off in the seedbed is caused by Pythium, Fusarium and Sclerotinia, wilting by white rot (Sclerotium rolfsii) and Verticillium dahliae. Powdery mildew (Leveillula taurica) is reported from Sudan and East Africa during the cool season. General control methods are the use of healthy seed, seedbed disinfection, good ventilation (not too dense planting), and good soil drainage. Many fungicides are available for chemical control.

– Bacterial diseases. Bacterial wilt (Ralstonia solanacearum) causes heavy plant losses. Some sweet pepper cultivars such as the popular ‘Yolo Wonder’ are very susceptible, other cultivars such as ‘Narval’ from Guadeloupe are medium resistant. Chillies are less susceptible and aromatic pepper and bird pepper are almost completely resistant. Bacterial wilt is partially controlled by a good drainage, e.g. raised beds during the rainy season. Bacterial spot (Xanthomonas campestris pv. vesicatoria) is controlled by the use of healthy seed. Other bacterial diseases are bacterial canker (Corynebacterium michiganense) and bacterial softrot (Erwinia carotovora).

– Nematodes (Meloidogyne, Xiphinema). Damage may be avoided by crop rotation with cereals, pulses or vegetables that are not host plants, and the application of much organic manure. Resistance to Meloidogyne incognita was found in the aromatic hot pepper cultivar ‘Scotch Bonnet’.

– Insects and mites. The mite Polyphagotarsonemus latus causes virus-like deformations of leaves and shoot tips. Thrips, the main problem in protected cultivation of sweet pepper, sometimes cause heavy damage in hot pepper fields during the dry season. Irrigation by overhead sprinkling reduces thrip damage. Other pests are caterpillars (Heliothis, Spodoptera), aphids, whiteflies, fruit flies (Atherigona orientalis) and termites (Microtermes). Since most of these are polyphagous, control is difficult. Inappropriate pesticides and over-use of pesticides often worsen pest problems, especially by thrips and mites. Control of caterpillars with Bt (Bacillus thuringiensis) or neem (Azadirachta indica A.Juss.) products spare natural predators.

Harvesting

Capsicum peppers are ready for harvest 2–3 months after transplanting, 3–6 weeks after flowering, depending on the fruit maturity desired. Sweet peppers as well as hot peppers are harvested at the green mature stage or at full maturity, depending on demand and utilization. Green harvesting stimulates fruit setting and gives a higher yield than harvesting at full maturity. Green fruits are sufficiently mature for harvest when firm; sweet peppers, if gently squeezed, make a characteristic popping sound. Harvesting is done by hand, except for big fruits and sweet peppers that are harvested with a small knife. The picking of small-fruited types like bird peppers is very labour intensive. Chillies or sweet pepper destined for trade as dried fruits, powder or oleoresin are left to dry on the plant before harvesting.

Yield

Hot pepper yields vary widely from 1.5–18 t/ha fresh product. Sweet pepper may yield up to 30 t/ha in the field and up to 100 t/ha in protected cultivation. The yield level in African countries is generally very low as a consequence of extensive cultivation technology. In Ethiopia the average yield of dried fruits is 400 kg/ha in sole cropping (equalling about 1600 kg/ha fresh product); the maximum yield is 2 t/ha of dried fruits (8 t/ha fresh).

Handling after harvest

Capsicum is handled for fresh consumption or processed into canned, pickled, frozen, fermented, dehydrated or extracted products. Usually the fresh fruits are sold in the market. Marketing in big cities is conducted through wholesale to retail markets, but much is also sold in small street markets through more informal marketing channels. If the price is low, harvested fruits may be sun-dried. This takes place in a vacant field or along roadsides, on mats or a well-swept area. The fruits are put in layers 2–3 fruits thick in the sun and are turned frequently; they will dry adequately in 10–20 days. The weight loss during drying is 60–80%. Dried fruits are used for preparation of powder or in ketchups and mixed spices. Handling of dry hot peppers for processing or seed extraction is very unpleasant because of the dust containing capsaicin, and precautions for protection of the skin and eyes are needed. Fresh fruits can be stored for up to 5 weeks at 4°C and 95% humidity. Dried capsicum may be stored for many months to supply year-round demands.

Genetic resources

An extensive germplasm collection of over 3000 accessions is held in the United States Plant Germplasm System, and another global collection is present at the Asian Vegetable Research and Development Center (AVRDC) in Taiwan. Other collections are held at the Centro Agronómico Tropical de Investigatión y Enseñanza (CATIE), Turrialba, Costa Rica, at the Centre for Genetic Resources (CGN), Wageningen, Netherlands, and at the Central Institute for Genetics and Germplasm, Gatersleben, Germany. There are many working collections of Capsicum germplasm. In Africa collections are held at Bako Research Centre in Ethiopia, and at the Institute for Agricultural Research, Ahmadu Bello University, Zaria, Nigeria. Other collections of landraces and traditional cultivars are present in several African countries, e.g. Kenya, Sudan and Zambia.

The genetic diversity available within Capsicum has been little exploited. The fairly high degree of cross-pollination is responsible for much of the heterogeneity in collected accessions. The wild species are potentially important as genitors of valuable disease resistance genes. In Africa most farmers still save and use their own seed. In the future, many landraces and local cultivars are likely to disappear as African growers will switch to improved cultivars, and hence there is a need for collecting the traditional capsicum material and conserving it in genebanks.

Breeding

Much breeding work has been performed on sweet pepper in temperate regions. Many cultivars, at present mostly F₁ hybrids, are commercially available for glasshouse and field production. Capsicum shows rather strong heterosis effects for plant growth traits and yield. The use of molecular markers and doubled haploids is quite common. Capsicum is very appropriate for the development of F₁ hybrids, with cultivars superior in yield, uniformity and disease resistance. Hybrid seed is produced by hand emasculation and pollination of the right inbred lines, a very labour-intensive method. The use of cytoplasmic male sterility is advancing but still rather unreliable. Sweet pepper cultivars bred especially for tropical African conditions are scarce. Seed company Technisem supplies seed of cultivar ‘Capela’ resistant to high temperature, TMV and PVY, F₁ cultivar ‘Stella’ resistant to TMV, and ‘Arika’ resistant to TMV and PVY. The South African seed company Hygrotech has paprika cultivars grown in Zimbabwe for oleoresin production, e.g. the popular cultivar ‘Papri Queen’, which is an erect subshrub, resistant to powdery mildew, taking 95–105 days to fruit maturity, with elongated, thin-walled, red fruits c. 17 cm × 3 cm.

Breeding for hot pepper is far less developed than for sweet pepper. Resistance breeding for fungal, bacterial and virus diseases is promising. At Plant Research International, Wageningen University and Research Centre, Netherlands, resistance genes for anthracnose were found in chillies, bird pepper and aromatic pepper, as well as in Capsicum baccatum. Many African accessions with resistance genes against the important viruses have been reported. Some commercial cultivars, including superior F₁ hybrids for the tropics, are available from Korea, Japan, India, Taiwan, Thailand and Indonesia. Resistance breeding with local hot pepper cultivars in Indonesia (East-West Seed Company) resulted in hybrid cultivars with a certain degree of resistance to anthracnose, bacterial wilt and fruit fly. Breeding work has been reported from Nigeria (Zaria, Ilorin, Ibadan) and Ethiopia. In Africa F₁ hybrids are still rarely used because the seed is expensive and few F₁ cultivars bred for local African conditions are available. Technisem seed company selected cultivars for tropical Africa, such as the aromatic hot pepper cultivars ‘Safi’, ‘Antillais Caribbean’, ‘Jaune du Burkina’ and ‘Big Sun’, the chilli cultivars ‘Jalapeno’ and F₁ ‘Sunny’, and the bird peppers ‘Salmon’, ‘Soudanais’, ‘Thailande’ and ‘Pili Pili’. Breeding for disease resistance takes precedence in most programmes, although yield, abiotic stress tolerance (heavy rainfall, fruit setting during hot weather), earliness and market quality concerning fruit shape, pungency, flavour and colour are overall objectives for capsicum improvement in the tropics. An intertropical network for plant breeding known as LIRA was initiated since 1992 as a collaboration between the Institut National de la Recherche Agronomique (INRA) in France and the Ministry of Agriculture in Cuba. The objective is the breeding for durable resistance against worldwide potyviruses. Since 1994 Guadeloupe, Tanzania, Sudan and Senegal have joined this programme. In several African countries, national programmes and private seed companies play a role in supplying seed of improved cultivars. Heterogeneous local cultivars are better suited for homegardens and small scale farming because of the prolonged harvest period, but less for large-scale market production. A good seed yield of open pollinated cultivars is 500 kg/ha, for hybrid hot pepper 200 kg and hybrid sweet pepper 150 kg.

Research institutes and seed companies in Western countries are using more and more advanced biotechnology, such as isozymes for selection. At present they use molecular biotechnology, mainly Restriction Fragment Length Polymorphisms (RFLP), Randomly Amplified Polymorphic DNA (RAPD) and Amplified Fragment Length Polymorphism (AFLP) markers and double haploids derived from anther culture, for mapping the genome. Molecular markers are used for efficient screening on disease resistances and speeding up the breeding period. Crossings can be made with all cultivated and most wild Capsicum species using embryo rescue.

Prospects

Capsicum peppers have a high nutritional and economic value, but the average yield in Africa is still very low. With improved cultivars, especially hybrid cultivars, and higher input use and intensification of cultural practices, the yield level can be increased considerably. Sweet pepper cultivation should be extended to supply urban markets and in some countries for export. In West Africa the mild forms of the aromatic hot pepper merit attention. There is a need for heat-tolerant sweet pepper cultivars suitable for lowland cultivation. Breeding of hot pepper (chillies and aromatic hot pepper) and seed production based on local cultivars, with emphasis on resistance to pests and diseases, merits high priority. Practical knowledge on integrated pest management for capsicum in the tropics is lacking and requires much research as well as training of farmers.

Major references

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• Messiaen, C.-M., 1989. Le potager tropical. 2nd Edition. Presses Universitaires de France, Paris, France. 580 pp.

• Poulos, J.M., 1993. Capsicum L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 136–140.

• Poulos, J.M., 1994. Pepper breeding (Capsicum spp.): achievements, challenges and possibilities. Plant Breeding Abstracts 64(2): 143–155.

Other references

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Sources of illustration

• Poulos, J.M., 1993. Capsicum L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 136–140.

Author(s)

• G.J.H. Grubben

Boeckweijdt Consult, Prins Hendriklaan 24, 1401 AT Bussum, Netherlands

• I.M. El Tahir

Plant Genetic Resources Unit, Agricultural Research Corporation, P.O. Box 126, Wad Medani, Sudan

Correct citation of this article

Grubben, G.J.H. & El Tahir Ibrahim Mohamed, 2004. Capsicum annuum L. [Internet] Record from PROTA4U. Grubben, G.J.H. & Denton, O.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 22 December 2024.

• See the Prota4U database.