Unravelling the link between tree architecture and production potential in Theobroma cacao: implications for pruning strategies

Abstract

Current pruning recommendations for clonal cacao ( Theobroma cacao ) lack scientific support regarding tree architectural development. This study investigates the relationship between tree architecture and production potential using data from a long-term trial in Bolivia. We measured architectural and production traits on 331 seventeen-year-old grafted trees across five cropping systems, ranging from conventional monocultures to input-free dynamic agroforestry, and four genotypes. We differentiated the productive “leafless zone” from the “leafy crown,” measuring branch orders, diameters, lengths in the former, and crown geometry traits in the latter. Results demonstrate that, while cropping systems and genotypes significantly influence vegetative biomass, the structural drivers of pod production remain consistent. Production was strongly related to the vigor (diameter) and number of low-order scaffold branches (orders 1 and 2) after accounting for cropping system type and genotype. Modelling confirmed that trees with complex scaffold structures and thicker 1st-order branches produced significantly more pods and beans than those with simple structures, with crown projected surface and foliage height further enhancing production potential. These findings challenge standard pruning recommendations focusing mainly on leafy crown management. We conclude that production potential is determined by the development of scaffold branches in combination with effective crown management. Consequently, pruning strategies should evolve from simple canopy control toward preserving vigorous scaffold branches and optimizing the tree’s physiological capacity for fruit production. To support this shift, we propose an architectural typology based on the branching structure of the leafless zone in grafted cacao trees to assess production potential and guide pruning decisions.