DOUBLED HAPLOIDS OF COFFEA-CANEPHORA - DEVELOPMENT, FERTILITY AND AGRONOMIC CHARACTERISTICS

Doubled haploids (DH) of Coffea canephora Pierre were developed using haploid embryos which occur spontaneously in association with polyembr yony. The frequencies of polyembryonic seeds and haploid embryos varie d according to the parental genotypes. However, production of a large number of DH seemed possible from all genotypes. More than 750 DHs pro duced from various genotypes were grown under field conditions and eva luated for different characters of agronomic importance. Approximately half of DH genotypes did not survive, suggesting a strong, negative e ffect of homozygosity. Inbreeding depression is particularly severe on general vigor and reproductive aspects. For several characters studie d such as leaf shape, leaf rust resistance and hundred bean weight, co nsiderable genetic variations were observed within and between groups of DHs constituted by the DHs produced from the same clone. Despite th eir low vigor and reduced fertility, the DHs of C. canephora offer new possibilities in genetic research and coffee breeding.