Cytological observations inCoffea. IV

VI. Summary

1. A short description is given of the main morphological characters of two interspecific triploid hybrids (C. arabica × C. canephora); their growth habit is normal and leaf and flower characters are intermediate in shape and size when compared with their parents.

2. The meiotic behaviour of the chromosomes at microsporogenesis is given in detail; the expected abnormalities were observed at the distribution of the chromosomes at first and second divisions, resulting in the formation of sterile pollen grains which are extremely variable in size.

3. The megasporogenesis in this triploid is believed to show the same abnormalities as observed in microsporogenesis.

4. The sterility of some interspecific hybrids grown in Java, as suggested in previous articles, is therefore confirmed and cleared up.

5. The intimate pairing of some chromosomes at early prophase up to metaphase suggests the possible autotetraploid origin ofCoffea arabica.

6. The occasional association of a third chromosome at prophase and metaphase to groups of two suggests that some of thecanephora chromosomes may have regions analogous to ones of somearabica elements; nothing can be stated, however, regarding a possible genetical relationship betweenC. arabica andC. canephora.

7. Two progeny plants of a triploid, obtained from open pollinated flowers, revealed to have 2n = 44; it is suggested that they derived from cross pollination, 22 chromosome pollen from normalarabica plants in the neighbourhood having fertilized two occasional 22 chromosome egg cells of the triploid.