Abstract:
In the present paper the authors present the results of a genetic study concerning the erecta type of growth of the lateral branches of Coffea arabica L. The erecta mutant, which probably originated in Java, differs from normal coffee plants by having upright growing lateral branches instead of plagiotropic ones. However, in spite of the fact that both, the main shoot and the lateral branches grow in the same direction, the dimorphic nature of the branches still persists. The genetic studies carried out since 1933, which included the study of progenies of F1, F2 generations and backcrosses, have revealed that the erecta character is conditioned by one pair of dominant genes Er Er. It is not yet known whether all erecta plants, of different origins, have the same dominant gene, but investigations already in progress are expected to yield information on this matter. Of all genes so far studied in C. arabica, Er is the most completely dominant, the heterozygote being indistinguishable from the homozygote. The erecta gene has been found to show complete penetrance and a constant expressivity.
