Improved Norway spruce somatic embryo development through the use of abscisic acid combined with activated carbon

The combination of abscisic acid (ABA) and activated carbon increased Norway spruce (Picea abies L., Karst.) cotyledonary somatic embryo yields, increased the number of genotypes forming cotyledonary embryos, caused embryos to form that exhibited improved maturation characteristics, and reduced embryo production costs. Somatic embryos increased in size, showed larger apical regions, became more zygotic-like in shape, and showed higher percentages of epicotyl development upon germination. Analyses of medium for free ABA in the presence of activated charcoal showed a rapid decrease within a few hours followed by a gradual decline over the next few days with little change from 2 to 6 weeks. Gelling agents strongly affected ABA adsorption, with agar decreasing the adsorption of ABA compared to gellan gum (Gelrite, Phytagel). Over 4,000 somatic seedlings from 20 clones were produced and established in a greenhouse using the methods discussed, and approximately 1,250 seedlings representing seven clones were established in a field setting.