COMBINING ABILITY OF DOUBLED HAPLOIDS IN COFFEA-CANEPHORA P

Fifty-five doubled haploids (DH) of Coffea canephora were crossed with either heterozygous genotypes or DH in order to study their combining ability. Three agronomic trials were established. Marked hybrid vigou r was observed for all characters analyzed including yield. Large diff erences were evident among top-crosses involving different DH produced from the same parental clone reflecting the high level of heterozygos ity of clones. Factorial mating design analysis indicated that all gen etic variance was attributable to additive effects in estimates of yie ld as well as plant height and leaf characteristics. The general combi ning ability variance component was also predominant for stem girth an d susceptibility to leaf rust, although effects due to interaction wer e detected. Some hybrid combinations had yield comparable to standard clonal varieties. The implications of such results for breeding of Cof fea canephora are discussed. Particularly, the development of F1 hybri d varieties is envisaged.