Genetic improvement in cocoa

Abstract

Cocoa, Theobroma cacao L., is a perennial crop, originally from the South and Central America and normally cultivated in the tropics from latitude 18°N to 15S, mainly in small farms, under the shade of native trees. Although it has been explored by the Mayans and Aztecs since pre-Colombian times, only in the last 5060 years it has received some attention in respect to breeding. The cocoa beans are the major ingredient for the cocoa industry, for the manufacturing of chocolate and derivatives, cosmetics and medicines. Cocoa is cultivated commercially in South and Central Americas, Caribbean, Africa, Asia and in some Pacific Islands. But most of the cocoa currently produced in the world (around 70%) comes from West African countries, especially Ivory Coast, Ghana and Nigeria. The evidence of cocoa as a domesticated crop comes from archaeological findings in Costa Rica indicating that cocoa was already used as a drink by the Mayans as early as 400 BC. In the 14th century, the Aztecs regarded the cocoa as the food of the Gods, placing much emphasis on the sanctity of cocoa. The spread of cocoa around the world began during the Spanish colonialism (Bergman 1969). Christopher Columbus was the first European to come in contact with cocoa, who reached Nicaragua in 1502, searching for a sea route to India (Bergman 1969; Cheesman 1944). At that period, cocoa was already an important tree to the indigenous people. Cocoa beans were used as currency in some parts of Central America. It was Hernan Cortés, leader of an expedition in 1519 to the Aztec empire, who returned to Spain in 1528 bearing the Aztec recipe for xocoatl (chocolate drink) with him. The drink was initially received unenthusiastically and it was not until sugar was added that it became a popular drink in the Spanish courts. Its formula was kept as a secret to be enjoyed only by nobility. Eventually, the secret was revealed and the drinks fame spread to other lands (Purseglove 1968). As the cocoa drink had become so appreciated, the European demand for the product also increased at that time, as so the interest in other new lands for expanding cocoa plantings. The spreading of cocoa around the world is shown in Fig. 16.1 with the main routes taken by Spaniards, French and Dutch. There were attempts to satisfy Spanish domestic demand by planting cocoa in the Spanish colonies like the Dominican Republic, Trinidad and Haiti. In 1560, the cocoa from Caracas, Venezuela, was introduced in the Island of Sulawesi, in Indonesia. In 1600, the Spanish also introduced cocoa in Philippines. In 1615, the French became aware of the use of cocoa, a century after the first discovery of the chocolate drink by the Spanish court. By the mid-1600s, the chocolate drink had gained widespread popularity in France. The Spanish princess Anna of Austria married French King Louis XIII who introduced, among other Spanish customs, the drinking of chocolate at the French court. There was increasing interest by the Europeans for new lands for the cultivation of cocoa. The French introduced cocoa in many locations, such as the islands of Martinique and St Lucia in 1660, Dominican Republic in 1665, Guyanas in 1684 and Grenada in 1714. The Caribbean Islands of Martinique became one of the major cocoa producers by 1680. The English took this crop to Jamaica by 1670; and, the Dutch took over plantations in the Curaçao islands in 1620 and introduced cocoa from Philippines to Indonesia and Malaysia in 1778. Cocoa was introduced to Bahia, in 1746, with seeds coming from Para, a northern State of Brazil. With the increase in demand for chocolate in Europe, more areas were required for expanding the cocoa plantings. Thus, the cocoa was taken to Africa in the beginning of the eighteenth century with the introduction of the Amelonado cocoa from Brazil to the islands of Príncipe (1822), São Tomé (1830) and Fernando Pó (1854). Later on, cocoa was introduced in the African continent, when it was taken from the Island of Fernando Pó to Nigeria (1874) and Ghana (1879) and, in 1905 cocoa arrived to the Ivory Coast, presently the worlds largest cocoa producer. In Cameroon, cocoa was introduced during the colonial period of 19251939 (Paulin and Eskes 1995). There are also reports on two introductions of Trinitario cocoa from Trinidad to Sri Lanka in 1834 and 1880. And later, this variety was introduced to Singapore, Fiji, Samoa, Tanzania and Madagascar, from Sri Lanka. In Java, the failure of the coffee crop in 1880 encouraged the farmers to grow cocoa (Paulin and Eskes 1995; Purseglove 1968). Cocoa occurs naturally in the South of Mexico to Bolivia and also in the Brazilian Amazon Forest. Due to the large genetic diversity of species observed, it was suggested that the cocoa tree originated in the Upper Amazon, in the zones of the confluence of the rivers Solimões, Putumayo and Caquetá. In spontaneous distribution, the cocoa tree is found in the lower stratum of the forests, in glades and on the banks of the great rivers, where high temperature and high humidity prevail (Cheesman 1944; Cuatrecasas 1964; Bartley 2005).