Desarrollo del vástago vegetativo en Coffea arabica L. cv. bourbon Choussy. I Ontogenia del ápice de la plántula

Abstract

This paper discusses the ontogeny of the vegetative shoot apex In Coffea arabica I. c. bourbon Choussy. The shoot apices of mature embryos, of seedlings in various developmental stages, and of adult plants were studied. With the initiation of the first leaf pair (35-40 days after planting) the cells of the peripheral region of the apex display a high cytoplasmic staining, which contrasts with the lightly stained cells of the axial zone. This is partially due to a low cytoplasmic concentration of R N A. It appears that the shoot apex of a young coffee seedling consists of two cytohistological and histochemical zones: I, the axial zone, which includes the axial cel1s of the tunica, corpus initials and rib meristem and II, the peripheral zone which consists of the peripheral cells of the tunica and corpus derivatives. The apices of young seedlings become zonate at the stage of maximal area in the first platochrons; however, no significant zonation was observed in the shoot apices of older plants. The competition among celIs for certain metabolites is suggested as one of the possible causes of the zonate appearance of the apices of young seedlings.