Genetic-base broadening of Robusta coffee: Assessment of genetic variability for vigor and yield of introduced germplasm

Abstract

The genepool of Robusta coffee in Ghana has been shown to be narrow and this necessitates the introduction of germplasm from foreign sources which may be repositories of important alleles for key traits. This represents a key facet of Robusta coffee development approach of broadening the genepool to overcome possible yield stagnation of the crop. The present study was set out to determine the agronomic potential of some introduced Robusta coffee genotypes and estimate genetic parameters for important growth and yield traits to direct future improvement strategies of the crop. Following a randomized complete block design with four replications, sixty-seven genotypes including one standard clone were planted in the field in June 2013 and evaluated for three traits: stem diameter, span and yield. There was significant variation ( p < 0.001) among the genotypes for all the traits assessed. Cumulative yield ranged from 8.6 t ha −1 to 14.5 t ha −1 among the top 22 genotypes. Thirty-one percent of the genotypes assessed had a cumulative yield that was equal to or higher than that of the standard. Our results showed that selection based on average first three years’ yield could be as effective as selection based on cumulative yield. Our findings document the extent of genetic variation for highly valued growth and yield traits in the Robusta coffee germplasm collection and provide evidence of the potential to increase productivity through the use of introduced germplasm beyond local collections in future breeding efforts.