EFFECT OF ABSCISIC-ACID, OSMOLARITY AND PARTIAL DESICCATION ON THE DEVELOPMENT OF RECALCITRANT MANGO SOMATIC EMBRYOS

Inhibition of mango somatic embryo growth was induced in vitro by trea tments for 4 or more weeks with abscisic acid (0-100 mu M ABA) with an d without high osmolarity provided by mannitol (0-10%). High osmolarit y and ABA significantly affected somatic embryo length, precocious ger mination and the production of good quality secondary somatic embryos. High osmolarity also affected root elongation. Abscisic acid was more effective in suppressing growth and development of greater than or eq ual to 0.5 cm-length somatic embryos than smaller somatic embryos. Dev elopment beyond the heart stage was significantly inhibited by both AB A and mannitol treatments. The recovery of good quality somatic embryo s was enhanced by high levels of ABA (100 mu M) with and without manni tol (0-5%). Somatic embryos that had been pulsed with ABA were partial ly desiccated at different relative humidities. Weight loss was affect ed only by relative humidity; and ABA did not enhance desiccation tole rance.