Ecology and Development Series No. 10, 2003 - ZEF

Current state of knowledgecultivars growing elsewhere, since the natural pollinating agents that evolved with thespecies are found in the natural habitats. Meyer (1965) observed 40-60% self-fertility in thewild coffee plants in SW Ethiopia, which indicates the possibility of a higher out-crossingrate.It takes 7-9 months for coffee fruits to mature. A matured fruit is about 1.5 cmlong, oval-elliptic in shape, and has a short pedicel. Immature fruits are green and turnyellow on ripening, and then red when fully ripened. The fruit consists of a smooth, toughouter-skin or exocarp, soft yellowish pulp or mesocarp and greyish-green, fibrous endocarp(= parchment) surrounding the two seeds. The seeds are 8.5-12.5 mm long at maturity;ellipsoidal in shape, pressed together with a flattened surface on the inside that has a deepgroove, and a convex outer surface. A thin, silvery testa (= silver skin) follows the outlineof the endosperm, so that fragments are often found in the ventral groove after preparation.Seeds consist mainly of green corneous endosperm, folded in a peculiar manner, and asmall embryo near the base. Polyembryony has been recorded (Purseglove 1968).The main means of propagation of cultivated coffee in commercial plantations isplanting seedlings raised from seeds. There is no seed dormancy, but the seeds are shortlivedand their viability decreases rapidly after six months when stored at ambienttemperatures. It is advisable to plant within 2 months of harvesting (Purseglove 1968).Vegetative propagation is sometimes used for multiplying clones and for top-workinginferior plantations. Top-working is the process of changing the top of an established treefrom one cultivar to another, or to multiple cultivars, by budding or grafting (Purseglove1968).2.3 Geographical distribution of wild populations of Coffea arabicaThe genus Coffea occurs in the tropical regions of the African continent and thesurrounding islands in the Indian Ocean. All economically important species of the genus,i.e., C. arabica, C. canephora, and C. liberica are restricted to African continent. Thediploid taxa occur mostly in the rain forest areas of Uganda, Kenya, Tanzania, Congo andWest Africa and as far north as Sierra Leone (Meyer 1968). Moreover, the diploid coffeespecies often have overlapping ecological distribution in eastern and central Africa, and19