BREEDING OF COCOA TREES (THEOBROMA CACAO L.) RESISTANTTO PHYTOPHTHORA MEGAKARYA, AGENT OF BLACK POD DISEASE IN COTE DIVOIRE

Backgrownd : Black pod disease is the cause of significant production losses of cocoa trees. This work aims to select tolerant and resistant genotypes to Phytoththoramegakarya within the main collection of cocoa trees of the National Center for Agronomic Research. Methods : The artificial inoculation test on leaf discs, was used in this study to assess the susceptibility of 52 clones of high-producing cocoa trees resistant in the field to black podcausing by P. megakarya. Results : Three groups of susceptibility to P. megakarya were demonstrated according to the reference controls. The first group is composed of two clones (IFC 1035 and CC 39) qualified as susceptible to black pod. These genotypes have respective sensitivity scores (NS) of 3 and 3.06 which are lower than those of the sensitive control NA32 (NS = 3.31). The second group is composed of 43 clones qualified as moderately resistant with sensitivity scores higher than 2.59 (PA150, moderately resistant control) and lower than 3.31 (NA32). The third group is composed of four clones qualified on the one hand as resistant (IFC 1041 and IFC 1027) with sensitivity scores higher than 1.73 (SCA6) and lower than 2.59 (PA 150) and on the other of very resistant to P. megakarya (NS> 1.73), with sensitivity scores greater than 1.73 Conclusion : These genotypes resistant to P. megakarya thus selected could constitute parents to be included in a variety improvement program with a view to the selection of plant material resistant to black pod disease.