Characterization of the Genetic Diversity of Timor Hybrids Based on Granulometric, Morphological, Agronomic, and Sensory Traits

Timor hybrids (HdT) are natural interspecific hybrids between Coffea arabica and Coffea canephora that are widely used in breeding programs. They are one of the main sources of genes for resistance to pathogens such as Hemileia vastatrix, Colletotrichum kahawae, Pseudomonas syringae pv. garçae, and nematodes such as M. exigua. The Federal University of Viçosa maintains one of the largest collections of HdT germplasm in Brazil. Expanding the molecular, morphoagronomic, sensory, and chemical characterization of these accessions is essential to maximize their use in coffee breeding programs. The objective of this study was to characterize the genetic diversity of HdT accessions belonging to the Active Germplasm Bank (BAG) of Coffea spp. at the Federal University of Viçosa (UFV) based on granulometric, morphoagronomic, and sensory characteristics of the beverage. Data from 55 HdT accessions were analyzed for the following traits:  percentage of beans retained on sieve size 16 or larger, percentage of peaberry beans, crown diameter (cm), length of the plagiotropic branch (cm), number of nodes on the plagiotropic branch, rust and cercosporiosis incidence (scores from 1 to 5), and the cup quality score obtained through sensory evaluation. The collected data were standardized and used to calculate the Euclidean distance matrix among the accessions. The genetic divergence was assessed using hierarchical cluster analysis via the UPGMA method. A principal component analysis was performed to identify the variables that contributed the most to the discrimination of accessions. Seven clusters were established by the dendrogram. The clusters comprised genotypes belonging to the same progeny, indicating that, as expected, genotypes sharing a common parental origin exhibit greater genetic similarity. The first two principal components explained 56.5% of the total variation. The traits that contributed most to the discrimination among accessions in components 1 and 2 were the percentage of beans retained on sieve size 16 or larger, cercosporiosis incidence, crown diameter, the length and number of nodes on the plagiotropic branch, and the percentage of peaberry beans, indicating that the divergence among accessions is concentrated in bean size, resistance to cercosporiosis, and traits related to plant architecture. The cup quality score did not contribute to genotype discrimination , as all accessions exhibited a specialty coffee profile, demonstrating the uniformity of the sensory quality of the HdT germplasm from UFV. Overall, the results confirm the existence of genetic diversity within the HdT collection, with most of the variation concentrated primarily in morphoagronomic and granulometric traits.