EFFECT OF THE ANTHER DEVELOPMENT STAGE AN D A HEAT-SHOCK ON ANDROGENESIS IN COFFEA-ARABICA L VAR-GARNICA

Floral buds 3 to 4 mm in length were removed from Coffea arabica L. va r. Garnica, with a view to inducing callus and embryo formation from t he anthers ; these buds had pollen grains with a single nucleus (befor e initial mitosis), mitotic grains (during initial mitosis) or binucle ate grains (after initial mitosis) and were subjected to a temperature of 5-degrees-C for 24 and 48 hours and to 25-degrees-C for 24 and 48 hours. The anthers were removed aseptically and cultured on a medium c onsisting of Murashige and Skoog salts with sucrose, mio-inositol, thi amine, cistein, indolebutyric acid, indolacetic acid, benzyladenine, 2 -isopentyladenine and gelrite, and the pH was adjusted to 5.8. After t wo weeks, growth of white, friable calli with a dihaploid (2x = 22) ch romosome set was observed only on the pollen grains with a single nucl eus. The calli were transferred to a culture medium where embryogenesi s only occurred with the treatment that had received a temperature of 5-degrees-C applied for 24 and 48 hours, with more abundant results in the latter case. The embryos were subcultured in a growth medium ; of the plants that developed, 10 % were normal (4x = 44) and 74 % had sm all leaves (2x = 22) ; the other types of plants had purple, albino or narrow leaves, probably due to gametoclonal variation, and most of th em had a dihaploid number of chromosomes. The embryos that developed t heir first pair of leaves were grafted onto C canephora seedlings that had germinated a short time before, to then double the number of chro mosomes with colchicine, apart from those that were already tetraploid . The tetraploid plants obtained in this way were planted out in the f ield for assessment.