Direct organogenesis and plantlet regeneration from mature zygotic embryos of masson pine (Pinus massoniana L.)

Mature zygotic embryos of masson pine were cultured as initial explants to investigate the process of direct organogenesis. Adventitious buds were initiated on DCR medium (Douglas-fir cotyledon revised medium) supplemented with 0.5 mg l(-1) N-6-benzyladenine (BA) and 0.05 mg l(-1) indolebutyric acid (IBA) or alpha-naphthaleneacetic acid (NAA). The highest induction frequency of adventitious buds was 99.3%. Subsequent transfer of buds to medium with lower concentrations of plant growth regulators in time was necessary for differentation of high quality adventitious buds. After culturing on elongating medium, in which the proportion of cytokinins to auxins was reduced, shoots higher than 2 cm were transferred for root induction to GD medium with half of the concentration of macro-salts (1/2 GD) and with 2 mg l(-1) IBA and 0.05 mg l(-1) BA. The average root frequency was over 70%. After adventitious roots had appeared, the shoots were transferred to 1/2 GD medium with a lower concentration of IBA (0.2 mg l(-1)) for further root development.