Genetic and Phenotypic Diversity of Robusta Coffee (Coffea canephora L.)

Abstract Tree morphological characters have a direct relationship with bean physical qualities that ultimately determine the market and price of coffee. This work assessed tree and roast bean phenotypic variability in the Robusta coffee so as to be able to inform markets the appropriate selection criteria for these two traits. Two hundred and six C. canephora genotypes from 21 traditional growing districts and three on station germplasm collections were evaluated using nine quantitative coffee descriptors for morphological traits and four roasted bean physical characteristics. Girth diameter increased with age, vigor was closely associated with production capacity and all the leaf characters with the exception of number of stems were also closely associated. Hybrids with a significant Mahalanobis distance ( D 2 ) were distantly unrelated to nganda and erecta whereas, commercial types, nganda and erecta types with insignificant D 2 values were closely related to each other. About 80% of the beans were of screen size 15 (>) while 61% were of the average size, 15. Denser beans of screen sizes 15, 15(>), and 18 had longer roast time but lesser weight decrease. The Robusta local landraces in Uganda are endowed with tremendous, genetic variability, and present opportunities for selection of yield, abiotic, and biotic stresses and cup quality.