Breeding of Fruit and Plantation Crops

Cocoa

• Cocoa: Theobroma cacao
• Family : Sterculiaceae (Malvaceae)
• Theobroma is the name given by Linnaeus meaning “Food of the Gods” (Greek name Theos = Gods and Broma = Food) to the chocolate tree cocoa. Theobroma bicolor and grandiflorum are other better known species. T. bicolor is typical with the inflorescence appearing in the axils of new leaves and the branches bent down as the pods reach maturity. Seeds of Theobroma bicolor are used as adulterant. Theobroma cacao is a diploid with 2n = 20. Theobroma cacao ssp.cacao includes Criolla populations of Central and South America and Theobroma cacao ssp. sphaerocarpum which includes other populations like Forastero and Trinitario.


Classification:

• The most accepted classification divides cultivated and wild cocoa into 3 groups, based on Venezuelan terminology namely Criollo, Forastero and Trinitario.

Criollo

• Pods yellow or red when ripe, usually deeply furrowed, often markedly warty, usually conspicuously pointed, pod wall thin in section so that pod compresses under hand pressure; seeds large, plumpy and almost round in cross-section; cotyledons white or pale-violet. Beans ferment quickly; comparatively low yield. It produces the best quality cocoa; but only small quantities are available in the world market. Criollos typically lack vigour and jorquette. They are reported to be extremely susceptible to bark canker, witche’s broom and cocoa swollen shoot virus. Two types are distinguished in criollo. Central American criollo, the unripe pod is green in colour and turns to yellow while ripening; Venezuelan criollos, this cultivar shows greater degrees of variation from tree-to-tree in colour, size and shape of pods. The unripe pod is usually red in colour.


Forastero

• This is a large group which consists of cultivated, semi-wild and wild populations. Of this, Amelonado population is the most extensively grown. Unripe pods are whitish or green and turn yellow on ripening, usually inconspicuously ridged and furrowed, surface often smooth, ends rounded or very bluntly pointed, pod walls relatively thick and often with a woody layer, difficult to cut, seeds flattened, fresh cotyledons deeply pigmented and dark violet cross-section; usually giving an astringent product. These are hardier, more vigorous and higher yielding than criollo types.


Trinitario

• These are hybrid populations result from natural crosses between criollo and forastero types. They are highly heterogeneous showing wide range of morphological and physiological characters. Colour of unripe pod may be whitish, green, red, variable in shape and wall thickness, surface ranging from smooth to warty; beans plump to flat; pigmentation of cotyledons white to nearly black. They are hardier and more productive than criollo, the best clones combine the vigour of Amazonian with much of quality of criollo, while other clones are very inferior.