Effectiveness of juvenile tree growth rate as an index for selecting high yielding cocoa families

Understanding the relationship between vegetative vigor and productivity in cocoa is critical to maximizing yield per unit area in cocoa plantations. Three trials established from either progenies of self mating of 24 clones of Upper Amazon origin, or from progenies of mating among clones recommended as parents for production (Seed Garden clones) or from progenies of inter- and intra-group mating of selected clones were analyzed for their vigor and yield relationships over a period of 10 years. The rate of increase in tree trunk cross-sectional area (TCSA) prior to bearing was an effective parameter in identifying families with large cumulative yields over the first five or six production years. Families with slow increase in juvenile TCSA were particularly of low bean yields. Though girth of adult trees was generally correlated with cumulative yields, a consistent relationship between tree girth at the end of the 10th year and yield efficiency was not observed. Yield efficiency was significantly correlated with cumulative yield, and showed predominantly additive gene action. The combined selection for rapid increase in juvenile tree TCSA and precocity have the potential of identifying high yielding families early in a cocoa breeding program. (C) 2012 Elsevier B.V. All rights reserved.