CYTOKININ PULSE-MEDIATED SHOOT ORGANOGENESIS FROM COTYLEDONS OF SITKASPRUCE [PICEA-SITCHENSIS (BONG.) CARR.] AND HIGH-FREQUENCY IN-VITRO ROOTING OF SHOOTS

Shoot formation from cotyledons of Sitka spruce was induced by a 2 h i ncubation in an aqueous solution of 400 mu M benzyladenine, followed b y culture on medium lacking plant growth regulators. Several basal med ia were assessed. Murashige and Skoog (1962) based medium was found to be optimal on which, after 25 weeks, 62.5% of cotyledons produced sho ots with a mean of 10.7 shoots per cotyledon. Shoots, detached from co tyledons and propagated individually by axillary bud proliferation, ro oted with a frequency of 84% following culture in half-strength MS-bas ed medium lacking growth regulators under low illumination (1.5 mu mol m(-2)s(-1)). Rooted plants were successfully transferred to ex vitro conditions.