Browsing by Author "Tahi, G.M."

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    Resistance to Phytophthorapalmivora (Butler) Butler Assessed on Leaf Discs of Cacao (Theobroma cacao L.) Hybrid Trees
    (2009) N'Guetta, S-P.A.; N'Goran, J.A.K.; Akaza, M.J.; Kebe, B.I.; Tahi, G.M.; Sangare, A.
    To select resistant cacao genotypes to Phytophthora palmivora and better understand the genetic determinism of resistance to this pathogen, the individual resistance of 133 and 105 two ways cocoa hybrids trees of two related progenies, Fl andF7, respectively, was evaluated by leaf discs test. The Fl andF7 derived from crosses (P7 x ICS100) x Cl (P7 x ICS95) x Cl, respectively. P7 is a resistant heterozygous Upper Amazon Forastero clone; ICS100 and ICS95 are less susceptible genetically close Tnnitario clones. The common male parent, Cl, is a completely homozygous susceptible Lower Amazon Forastero clone Amelonado type. Three series of inoculations were conducted per family and one-hundred and twenty leaf discs taken from each tree were inoculated. The results showed additivity of transmission of resistance to P. palmivora, the presence of a transgression for this character and the involvement of several recessive alleles in resistance to Phytophthora. Significant differences in levels of resistance were observed between the genotypes of each progeny. The average levels of resistance of Fl and F7 are intermediate between those of both resistant controls SCA6 and PA150 and that of NA79, the susceptible control. In the Fl and F7, respectively, 24 and 05 cocoa trees were more resistant than SCA6 and PA150. These trees may be selected and may serve as potential new genitor clones in Phytophthora sp., genetic resistance breeding programs. They may also provide budwoods for replacements in fields.