Yield stability in Coffea canephora from diallel mating designs monitored for 14 years.

The genetic parameters of several agronomic traits were estimated in Coffea canephora in a triangular diallel with six parents and in a partial diallel with 18 parents. The yield data came from harvests obtained over 14 years divided into an initial 6-year cycle, a second cycle of 5 years after cutting back and a third cycle of 3 years after topping. Risk incidence was also observed over several years. The general combining abilities (GCA) were the principal sources of variation for the various traits considered. Parents derived from the Yangambi selections (Democratic Republic of Congo) proved to be best for yields in the three cropping cycles. The rank correlations between the GCA of the various traits indicated that first-cycle production was still not enough to predict the GCA for yield over 14 years. Susceptibility to leaf anthracnose and to drought could lead to modifications in successive classifications, with a more significant impact on production during the first cycle. The differences in susceptibility to Coffee Berry Borers had an impact on yield, which increased in line with coffee tree age. There was a rather good relation between inherent values and values in parent combinations and it was thus possible to choose parents on their own performance.