Resumo:
The Coffea arabica L. variety rugosa has been characterized as having rugose or roughened leaves. However, progenies of this variety obtained from selfed and open pollinated flowers have not, as observed to date, produced plants with characteristic rugose or definitely roughened leaves. This lack of rugose leaves in the seedling progeny of the variety rugosa led to the present cytological investigation to determine whether rugose leaves might be due to differences in the polyploid nature of the component leaf layers. Chromosome counts were made in cells of tissue obtained from root tips of seedlings and from root tips from stem cuttings, and from very young leaf buds. Chromosomes were also counted in the microsporocytes and in the microspores. The results of the cytological observations indicate that in the plant tissues examined there was an average number of 44 chromosomes. The counting of chromosomes in the coffee leaf buds was difficult due to the small size of the chromosomes. Observations also showed that microsporogenesis in the variety rugosa was normal and that the microspores contained 22 chromosomes. The results of this investigation show that Coffea arabica L. var. rugosa is a tetraploid plant, as are several other varieties of C. arabica that have been studied. The cytological observations also show that the rugose or rough condition of the leaves is not due to the presence of tissue layers of different polyploid nature.
