Resumo em Inglês:

This paper presents the results of cytological observations on microsporogenesis in the self-sterile species Coffea canephora. It was found difficult to study chromosome structure in the first stages of meiosis because the chromosomes do not stain well with aceto carmine and could be seen only as long faintly threads with some heteropycnotic regions. In many observations of the pachytene stage it was possible to observe and study a chromosome attached to the nucleolus. This chromosome characteristically had a visible centromere which divided it into two arms of different sizes. The short arm was attached to the nucleolus and had several heteropycnotic regions. In the long arm the heteropycnotic regions were observed to be close to the centromere ; the distal portion of this arm was only faintly stained. Other chromosomes in the pachytene stage were found to have a conspicuous centromere located between two highly heteropycnotic regions. The heteropycnotic regions in some chromosomes were located near the centromere while in others they were observed to be scattered throughout the chromosome. In diakinesis the chiasmata were counted and there were found seven chromosomes with one chiasma, three chromosomes with two chiasmata and one chromosome with three chiasmata. The average number of chiasmata per cell was 15.88. In metaphase the average number of chiasmata per cell was found to be 14.57, which is less than the average per cell in diakinesis. Anaphase I appeared normal as did all subsequent phases of meiosis, that resulted finally in the development of four microspores with eleven chromosomes each. Very few pollen mother cells with abnormal numbers of chromosomes were observed. On the basis of this study, it is concluded that microsporogenesis in Coffea canephora is normal.

Resumo em Inglês:

A study has been made of the embryo sac in self-sterile Coffea canephora flowers of different ages. The process was observed to be normal and included the formation of two synergides and one egg cell in the micropilar region, three antipodals at the chalazal region and two polar nuclei lying in the middle of the sac. It is known that in the species C. arabica the embryo sac formation is complete at the time the flowers open. Embryo sac formation in C. canephora is slightly delayed and it is not complete until the day following opening of the flowers. It was also determined that in C. canephora shedding of pollen begins shortly after the flowers open and the pollen was functional at least for two days. Thus the results of the present study indicate that the self-sterility of C. canephora flowers is not due to the delay in formation or abnormal development of the embryo sac.