Morphological Basis for Identification of Cup Quality Characteristics in F₁ Hybrids Derived from Coffea arabica L. Crosses

Abstract

The coffee quality, either of arabica (C. arabica L. var. arabica) or robusta (C. canephora Frohener. var. robusta) is an outcome of genetic behaviours performed under various environmental conditions and post-harvest processing techniques. The combination of these factors in an appropriate proportion produces the coffee quality to the degree of merit. Therefore, to study the genotypic influence on beverage quality and its relationship with morphological traits, 15 F₁ arabica hybrids were experimented at Coffee Research Sub Station, Chettalli, Kodagu District, Karnataka, India. The morphological parameters were recorded and correlated with the coffee quality parameters assessed by the Coffee Board, Quality Control Division, Bangalore. Results indicated the superiority in cup quality of an interspecific hybrid progeny of an arabica variety ‘Cauvery’ (Catimor) × (CxR) a robusta cultivar among all the hybrids and graded as ‘specialty coffee’ by the tasters. Sln.5B × Sln.9 scored the second place in quality rating parameters. Though, the other crosses such as Sln.6 × Cauvery, Tafarikela × S.4179 (Catimor progeny) and Sln.5B × S.795 had good liquor aroma, body acidity and other components but indicated low flavour intensity. The progeny of Sln.9 × Sln.11 recorded the lowest rank among the F₁ progenies probably due to introgression of diploid genes from liberica coffee being one of the parents in evolution of Sln.11. An interesting finding revealed that the plants with thick stem produced low flavour, and the thick primary induced low acidity in the cup. Besides this, internodal length, leaf length and breadth and size of fruit cluster exhibited positive correlation with other quality parameters like mouthfeel, aftertaste, flavour and overall as well as with 100 bean weight. The F₁ hybrids derived from the parents with robusta genetic background expressed lower acidity in the liquor. The findings of the present study revealed that the coffee plant with its inherent quality characteristics could easily be identified based on its phenotypic parameters such as stem girth, thickness of the primary branches, internodal length, leaf size and tightness of the fruit cluster. Further, the study also widened the scope to use these traits as quality markers to produce coffee to the consumers’ choice through genetically blended arabica and robusta varieties rather than physical blends of beans of both the varieties.