Care of plant material

Abstract

Two sorts of plant material can be used for in vitro isolation: plants grown under controlled conditions in a greenhouse (or growth room), and those grown outside (grown in the open field). In practice, if an expiant is isolated from a plant that has been grown outside, there is a much greater chance of infection taking place. Exceptions to this are tissues which are isolated from inside the plant: e.g. from the cambial zone of a shrub or tree, or from storage organs such as bulbs, tubers, rootstocks, etc. (Gautheret, 1959). If, despite the disadvantages material grown outside has to be used, then the following should be taken into account:

• 1. Buds should be used with bud scales, which are no longer dormant, although they have not yet burst.

• 2. Branches can also be used which have been held back (stored), and then forced in water inside.

• 3. Branches which have been grown outside can be enclosed in plastic, and only those parts which are subsequently formed used for isolation.

• 4. The youngest shoots formed outside should be used.