La sélection générative du cafeier Robusta au Cameroun; analyse des résultats d'un essai d'hybrides dialléle partiel implanté en 1973

Vegetative breeding of Robusta coffee tree in Cameroon led to the choice of selected clones, which are distributed in the form of cuttings in the cultivation areas. Generative breeding should result in the choice of selected hybrids which will be distributed in the form of seeds produced in bi- or polyclonal seed gardens. The generative breeding programme consists of nineteen comparative trials, comprising: six illegitimate progenies trials in the East of the country, two legitimate progenies trials in the East, and two trials in the West, two legitimate hybrids trials in partial dialled tables in the East and three others in the West, two legitimate hybrids trials in almost complete dialles tables in the East of the country and two in the West. The result of one of these trials, the 1973 hybrids trial in partial diallel tables carried out at the Barombi-Kang station, are analyzed. Eight parents, clones C6, B4, B5, B11, B15, B18, B31 and B40 were used. Each was involved in five combinations. Twenty hybrids were compared in this trial, which was carried out with five replications. The selection criteria were the following: productivity, tree vigour (rate of growth of stems and branches, diameter of stems and branches), grain size charateristics of the coffee produced and its caffeine content, susceptibility of the trees to parasites (leaf anthracnosis, berry borer). In the very large majority of the parameters studied, a highly significant different was revealed between the general combining ability of clones, whereas the specific combining ability was almost never significat. Among the eight parents use, C6 was the clone whose progeny was made of the most vigorous and most productive coffee trees. B40 is the clone whose progeny produced coffee with the most appreciated grain characteristics. The most productive hybrid is believed to be the cross between C6 and B5 clones