PROBLEMS OF SOIL ADAPTATION IN PLANTLETS OF COFFEA ARABICA L. OBTAINED VIA SOMATIC EMBRYOGENESIS

Clonal propagation of Coffea arabica L. can be achieved by induced somatic embryogenesis in vitro cultures of mature leaf explants. The protocol for obtaining perfect embryos bearing a bipolarity (shoot and root poles) consisted of a primary culture on a "conditioning medium" followed by culture on an "induction medium" as described by Söndahl and Sharp (1977). Afterwards we have used, instead of a solid medium, liquid media for further growth of these embryos. Experiments were conducted in order to see the effects of various plant growth regulators: benzylaminopurine (BAP); gibberellic acid (GA₃); indole acetic acid (IAA) and naphtalene acetic acid (NAA) on the morphology of the derived plantlets. It was found that GA₃ gives a good development of the hypocotyl but reduces cotyledonary leaves; BAP at optimal concentration (1.5 mg/l) gives a drastic increase of the cotyledonary area; IAA and NAA promote root development. In the selected medium (1.5 mg/l BAP; 1.0 mg/l GA₃ and 1.0 mg/l IAA) plantlets grown under illumination at 25°C mimic normal seedlings. Only plantlets that have a good development of the cotyledonary leaves survive when transferred directly from the liquid media into the soil.