CUCUMBER SOMATIC EMBRYO DEVELOPMENT ON VARIOUS GELLING AGENTS AND CARBOHYDRATE SOURCES

Somatic embryos were induced on cotyledonary explants of cucumber (Cucumis sativus, L. cv. Clinton). The somatic embryo tissue was induced and multiplied on a semisolid medium. The greatest vitrification and expansion of explants were observed when 0.15% Gelrite was the gelling agent. At the induction stage, explants on a medium gelled with 0.7% agar yielded more somatic embryo tissue, uncontaminated by callus, than explants on either Gelrite (0.15%, 0.3%, and 0.6%) or on 1.4% or 0.35% agar. In contrast to the induction stage, there was no effect of gelling agent on the fresh weight of putative somatic embryo tissue produced during the multiplication stage. When sucrose, glucose, or fructose was the sugar source in the multiplication medium, similar weights of tissue were produced. However, when sucrose was compared with fructose in the presence of either agar or Gelrite as gelling agent, the subsequent germination of the somatic embryos was higher when the tissue was multiplied on Gelrite in the presence of 3% sucrose. Maltose (3%) severely inhibited tissue multiplication.