ABSTRACT

A high degree of yield variation is a general characteristic of cacao plantations worldwide, due in part to the predominant use of seed propagation in this mostly self-incompatible and highly heterozygous tree crop (Figueira and Janick 1995). Some of the earliest studies on individual tree yield in cacao-producing fields and experimental plots demonstrated that only 7-20% of the trees propagated from seed produce the majority of the yield measured in dry weight of cocoa beans per ha (Freeman 1929; Cheesman and Pound 1932; Anonymous 1933, 1934, 1937; Shephard 1936; Pound 1945). Additionally, a study of the early yield of five high-producing cacao families grown in full sun in Puerto Rico reported that only 2-3% of the trees in the population produced more than 60% of the yield (Irizarry and Rivera 1999). Genetic improvements made by plant breeders are often rapidly lost as farmers propagate plants through seeds, and segregation results in highly

The potential of somatic embryogenesis for commercial-scale propagation of elite cacao varieties

The potential of somatic embryogenesis for commercial-scale propagation of elite cacao varieties

heterozygous populations of plants. Vegetative propagation systems provide a means to capture genetic gain and are commonly used for cocoa (grafting and rooted cutting techniques); however, these methods suffer from low multiplication rates and require several years to establish a nursery with sufficient numbers of individuals to support a large-scale propagation programme.