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Theobroma cacao

AuthorityL.
FamilyMagnoliopsida:Dilleniidae:Malvales:Sterculiaceae
Synonyms
Common namescocoa, cacao, koko, Kakao
Editor
Ecocrop code2074



Notes
DESCRIPTION: A small semi-deciduous cauliflorous tree 5-10 m high with a foliage canopy of 4-5 m in diameter when about 10 years old. When fully developed the taproot is 0.8-2 m deep. Lateral roots arise along its entire length but only develop to any great extent in the upper portion, usually from the collar to 15-20 cm down. Up to 10 branched lateral roots may develop in the topsoil covering a 5-6 m radius and with a mass of root hairs. The main trunk is short; branches in whorls of 5, dimorphic; vertical chupons growing from the trunk have leaves arranged in 5/8 phyllotaxy. The lateral branches (fans) have 1/2 phyllotaxy. Stems initially develop orthotropically then in successive elongation phases up to 18 months with a 1-1.5 m trunk. Further growth is interrupted by the degeneration of the terminal bud, below which the first 3-5 branch meristems develop simultaneously, in the form of a whorl growing horizontally. These fan branches form the framework of the tree and are refereed to as a 'jorquette'. The young leaves, which appear either as the trunk develops or during the flushes, are very often pigmented. They appear in accordance with a 3/8 phyllotaxy arrangement. Their colour may vary, depending on the tree type, from pale green, to pink, to deep purple. The young leaves are limp and pendant; as they mature, they become dark green and rigid. The leaves are coriaceous or chartaceous, alternate, and distichous on normal branches. The petiole has 2 joined pulvini, one at the base and the other at the point of insertion of the leaf. Stipules 2, deciduous. Lamina elliptical-oblong or obovate-oblong, simple, 10-45 cm long; generally smooth, sometimes hairy, rounded and obtuse at the base, pointed apex. The inflorescence is dichasial; primary peduncle very short, often thick and lignified. Flower peduncle 1-4 cm long. Sepals 5, triangular, whitish or reddish in colour. Petals 5, joined at the base into a cuplike structure, whitish-yellow with dark purple bands adaxially; ligules spathulate, yellowish. Stamens 5, fertile, alternating with 5 staminodes, the 2 whorls uniting to form a tube. Anthers 2, stamens fused. Ovary superior with a single style terminating in 5 sticky stigmatic surfaces. The fruit is 10-15 cm long and yellow or purplish and is variable in shape, ovoid, oblong; sometimes pointed and constricted at the base or almost spherical, with 10 furrows of which 5 are prominent. Axial placentation, the seeds (embedded in mucilage) flat or round with white or purple cotyledons. The fruit is attached to the branch or trunk by a woody stalk which was originally the stalk of the flower but which thickens as the pod develops. The pericarp or cortex of the pod consists of three distinct layers; the hairy and thick epicarp, which is more or less hard (the epidermis of which may be pigmented); the mesocarp, which is thin and hard and more or less woody; and the hairy endocarp, which is of varying thickness. Pods generally contain an average of thirty to forty seeds, an estimate which is convenient for a rough evaluation of yield in the plantation. However, the number of seeds per pod varies enormously. The cocoa seed or fresh bean is shaped rather like a plump almond, and is surrounded by a white mucilaginous pulp; which is both sweet and rather sour. The average dimensions of the seed are 20-30 mm in length, 12-16 wide and 7-12 thick. Cocoa seeds readily germinate when sown and do not pass through a dormancy period. They lose viability within 5-7 days of extraction from the pod unless specially treated, and germinate within 7-10 days. The plant can easily be propagated vegetatively by leaf-bud cutting, multiple-bud cutting, marcotting, budding, grafting and layering. USES: Food: The cocoa bean, with up to 50% fat, is a valuable source of vegetable fat: cocoa butter. The residual cocoa powder is used in cakes, biscuits, chocolate, drinking chocolate and other confectioneries. Fodder: The cocoa-pod husk has a low alkaloid content, while tannin is practically absent and husks are used as stock feed. The crude fibre content is low; it is completely unlignified and compares favourably with Panicum maximum and Centrosema pubescens. Fuel: The cocoa bean testa has a calorific value of 16 000-19 000 BTU/kg, a little higher than that for wood. Lipids: The ash from pod husks contains potassium oxide, which can be extracted in the form of potassium hydroxide, a useful alkaline in the saponification process. Cocoa-bean fat from unfermented cocoa beans can be extracted and used in soap making. Alcohol: The cocoa-pod husk can be hydrolysed under pressure for fermentation into alcoholic drinks. Medicine: Cacao butter can be used in cosmetics and has medical properties. The rural people in Amazonas State, Brazil, rub cocoa butter on bruises. Soil improver: There is considerable nutrient cycling through the development of a deep leaf litter under the cocoa canopy. Intercropping: Cocoa has traditionally been established in thinned forest following logging and 1-3 years of food-crop production before the canopy closes. Crops such as maize, cocoyam, yams and plantain are commonly intercropped with cocoa in Ecuador, Jamaica and West Africa. KILLING T.: Temperatures of about 5oC, even for a short period, may damage cacao but it is grown in Sao Paulo, Brazil, where normal winter temperatures reach 4-6oC. The tree is damaged by frost. GROWING PERIOD: Perennial tree, that begins fruiting after 3-5 years and bears well up to an age of 30-40 years, or even 60 years in the best soils before yields begin to decline. Fruit and seed require 180-300 days to mature. COMMON NAMES: (Burmese): kokoe, (English): cacao, chocolate tree, cocoa, Nicaraguan cocoa shade, (French): cacao, cacaotier, cacaoyer, (German): Kakaobaum, (Indonesian): coklat, (Khmer): kakaaw, (Malay): pokok coklat, (Sinhala): maikona gaha, (Spanish): cacao amarillo, cacao criollo, cacao forastero, (Tamil): kona maram, (Thai): kho kho. FURTHER INF.: The generic name comes from the Greek ?theos? (god), and ?broma? (food) and means the ?food of the gods?. In its natural habitat it is an under-storey plant of forest in the wet humid tropics. In most of the producing countries of America, Asia or Oceania, permanent shading is provided by specially-planted trees, most commonly Leucaena leucocephala, Gliricidia sepium, various Erythrinae or even Albizia species. Finally, other industrial crops are often used as permanent shading for the cocoa tree, the coconut palm in particular. Of other crops there have been several attempts to intercrop cocoa trees with rubber, oil palm, areca palm (Areca catechu) or even with nutmeg (Myristica fragrans). When planted at their normal density, all these plants produce too much shade for the cocoa trees, which develop as far as vegetation is concerned, but produce very few pods. Cacao originated in the Upper Amazon region in South America. It can be grown between 20°N and S, but the bulk of the crop is grown within 10°N and S, usually below 300 m in elevation but it can be found up to 700 m, and exceptionally up to 1500 m in equatorial regions. The photosynthesis pathway is C3. Cacao is best adapted to 75-86% relative humidity at 09.0 hours, and 51-72% at 15.0 hours, above this humidity level the risk of diseases is increased. Young seedlings have a shade requirement for optimal growth, but for the mature crop optimal yield can only be obtained under full sunlight. Situations where the temperature frequently falls below 18.8 C, or rises above 32.2 C are said to be unfavourable. Cacao is sensitive to strong winds. The amount of nutrients removed in the harvest is not very high if the fruit shells are brought back to the plantation and used as mulch. One ton of cacao beans remove about 20 kg N, 4 kg P, and 10 kg K from the field. Optimum yield of dry beans is more than 2.0 t/ha, while average yields in Africa vary between 0.2-1.0 t/ha. It takes 16-30 kg of pods to produce 1 kg of dry cacao. Cacao is naturally out-breeding, and various insects are associated with its pollination, the main ones being thrips, midges, ants and aphids. It has a complex system of self-incompatibility. After successful pollination, fertilization takes place within 36 hours; the sepals, petals and staminodes drop away and the stamens and pistil wither. The young pod, known as the cherelle, begins to develop by longitudinal elongation, followed by increase in width. The period between fertilization and pod maturation varies from 150 to 180 days, depending on the variety. The pod turns light yellow when ripe and is ready for harvesting at this stage. Fermented seeds are roasted, cracked and ground to give a powdery mass from which fat is expressed. Cacao has the distinction of being a birthplace of IPM and over the last 30 years cocoa has increasingly become a smallholder cash crop. An estimated 80% of the world's cocoa is now produced by smallholders.
Sources
Genetic Improvement of Cacao (FAO)
Purdue NewCROP
Wikipedia
Sims D (pers. comm.)
Eswaran 1986
Rehm S 1991 pp 258-262 [TEMP, RAIN, LIG, DEP, DRA, PH]
Roecklein J 1987 pp 14 [USE]
Kozlowski T 1977 pp 280
Williams C 1979 pp 97-112 [LIG, RAIN, TEMP, TEXT, FER, PH]
Williams C 1979a pp 51-60 [TEMP, KTMP, RAIN, FER, LIG, PH]
Kernick M 1961 pp 400
Nair P 1980 pp 193-200 [RAIN, TEMP, TEXT, FER, DRA, USE]
Onwueme I 1991 pp 447-453 [DRA, RAIN, TEMP, LIG, DEP, PH]
Hensleigh T 1988 pp 330-336 [DEP, DRA, FER, PH, TEMP, KTMP, RAIN, LIMITS]
Martin F 1984 pp 264-266 [TEMP, RAIN, PHO, DEP, DRA, FER, PH, LIG, USE]
Westphal E 1989 pp 265-270 [RAIN, TEMP, DRA, DEP, FER, PH]