Abstract

Increasing productivity is a main objective in Robusta coffee improvement in Ghana. A field trial was established in 1998 to evaluate the potential of ten Robusta coffee clones for optimal density planting, at the experimental field of the Cocoa Research Institute of Ghana sub-station, Afosu. The clones were evaluated at three planting densities (1667, 2222 and 2667 trees ha^-1) in a split plot design with three replicates, for yield and five vegetative traits namely: stem diameter, crown diameter, orthotropic internodes length, plagiotropic internodes length and number of bearing nodes per plagiotropic branch. Highly significant (P < 0.00) interaction effects were observed for all parameters measured. The highest yields (averaging 1289.5 kg ha^-1 year^-1) were obtained from the highest planting density with clones 197, A129, B191, 181, and A115. These clones also had a relatively compact growth habit (smaller stem diameter and shorter plagiotropic and orthotropic internode lengths) compared to the other five clones (E152, B96, E138, E139 and B36). The findings suggest that productivity increases in Robusta coffee could be achieved through the use of planting materials which combine compact growth habit and high harvest potential in close spacing planting scheme.

Keywords: High density planting, robusta coffee clones, vegetative vigour; yield potential.