Kawuki et al. 2026; UCDA 2019; Tree Genetics & Genomes 2025 (title)

Because canephora does not fertilize itself, no lineage can be fixed by sowing as with arabica: every seed is a hybrid between two trees. Breeders have therefore tried five routes. Java's mass selection and progeny tests (1907-1930) keep the best mothers and sow their seed: simple, cheap, but the offspring segregate and part of the gain is lost with each generation; this is still the principle of the Ugandan “Elite” (1995), given at 2,000 kg/ha. Clonal selection, made possible in Java by cuttings and grafting and then generalized (BP and SA series 1920-1940, Emcapa 1993, KR 2009-2017, Vietnamese TR), copies a superior individual identically: doubled yield (3,000 to 4,000 kg/ha of marketable coffee in Uganda against 1,500 for seed), grouped ripening, sure resistances, but the obligation to plant several compatible clones, a narrow genetic base and costly nurseries. The reciprocal recurrent selection of Côte d'Ivoire (1980s and 1990s) crosses the Guinean and Congolese groups and exploits heterosis, +16 to +140% in Leroy (1997), at the price of long cycles. Seed varieties derived from intercrossed clones, TRS1 in Vietnam or Conquista (2019) in Brazil, seek to make genetic progress accessible to small farms that cannot buy cuttings. Genomic selection, finally, tested since 2025 to guide the pairing of parents and take advantage of hybrid vigor, promises to shorten cycles that Kawuki estimates at more than twenty years per variety. The Nestlé program (clones Roubi 1-10) illustrates the private route, with unpublished parentage.

Kawuki et al. 2026, § 2.1 to 2.6 and 2.8; UCDA 2019, § 3.1.7 and 3.2, p. 23 and 27, table 1; Tree Genetics & Genomes, 2025, “Genomic-assisted selection to guide mate allocation and leverage hybrid vigor in Coffea canephora” (title as recorded); WCR 2024, poster, p. 3 (Roubi)