EFFECTS OF SEVERAL AUXINS ON SOMATIC EMBRYOGENESIS AND PLANT REGENERATION IN CASSAVA

Primary somatic embryogenesis could be directly induced from immature leaves of cassava (Manihot esculenta Crantz) on the MS solidified medium supplemented with higher concentration of 2,4-D (1-16 mg I/') or NAA (40 mg I/1), but IBA and IAA (40 mg L1) could not induce it. When the somatic embryo fragments were used as expiants, the need of auxin activity and concentration for the induction of secondary somatic embryogenesis decreased. The decrease of the concentration or activity of the auxins in the induction media could enhance somatic embryogenesis and root formation, and result in the increase of plant regeneration frequency. It was observed that somatic embryos could not develop shoot meristem on the induction medium containing 4 mg L"' 2,4-D. The experiments showed that the auxins stimulated the induction of cassava somatic embryogenesis but inhibited the development of somatic embryos and decrease plant regeneration in cassava.