Plant Propagation Technique
Modern plant tissue culture techniques are carryed out under aseptic conditions using highly filtered air in an enclosed, sterile environment. The surfaces of living plant materials are naturally contaminated from the environment with microorganisms, so surface sterilization of starting materials, also known as explants, in chemical solutions is a critical preparation step.
Explants will then be placed on the surface of a solid culture medium, but are occasionally placed directly into a liquid medium, particularly when cell suspension cultures are desired. Solid and liquid media are generally composed of elemental salts plus a few organic nutrients, vitamins and plant hormones. Solid media are prepared from liquid media with the addition of a geling agent, usually purified agar. The composition of the medium, particularly the plant hormones and the nitrogen source have significant effects on the development of the tissues that grow from the initial explant.
As cultures develop and grow, pieces are typically peeled off and transferred to a new media (subcultured) to allow for continued growth or to alter the morphology of the culture. Tissue cultuarists require significant skill and experience when judging which pieces to culture and which to discard.
As growing plant shoots emerge from a culture, they may be sliced off and rooted with a rooting agent to produce plantlets which, when mature, can then be transplanted to potting soil for further growth in the greenhouse as normal plants.