Improved somatic embryo production from embryogenic tissue of Pinus patula

Embryogenic tissue from six genotypes of Pinus patula (Schiede et Deppe) wa s subjected to a number of treatments to improve both somatic embryo matura tion and germination protocols. The use of a slightly modified 240 medium s upplemented with polyethylene glycol (PEG) significantly improved both the number and quality of embryos produced, especially at the 7.5 and 10% level . Various pre-germination treatments were tested to enhance embryo germinat ion. A partial drying treatment (PDT) at high relative humidity, lasting ap proximately 4 wk, gave the best germination results. Despite the beneficial effects of the PDT, embryos that had been harvested from the 240 maturatio n treatment containing no PEG gave the best germination responses when comp ared to the PEG-treated cultures. Plantlets were acclimatized ex vitrum, bu t success rates were low. Latent PEG effects were observed in acclimatized somatic seedlings.