EFFECT OF EXPERIMENTAL CONDITIONS AND GENOTYPIC VARIABILITY ON SOMATIC EMBRYOGENESIS IN COFFEA-ARABICA

The somatic embryogenic potential of leaf explants from greenhouse-gro wn plants of eight Coffea arabica genotypes was investigated on three different gelose-gelled culture media (Dublin, Pierson, and Yasuda). F our of these genotypes were reactive. Optimal somatic embryogenesis wa s obtained when the explants were taken from microcutting and cultured on gelrite-gelled Yasuda's medium. Under these culture conditions, so matic embryos and plantlets were obtained in two previously recalcitra nt genotypes. The histocytological callus development was found to be identical in responsive or recalcitrant genotypes. Embryogenic cells f ormed at two successive points during callogenesis and their subsequen t development varied according to culture conditions. Cells initiated in 10- to 15-day-old calli either degenerated or developed directly in to embryos. Cells initiated in 60-day-old calli became isolated and de veloped into embryos or their development was arrested. Embryos obtain ed in these conditions were able to develop into plantlets.