In vitro selection is used to screen large numbers of plants or cells for a
certain characteristic, for example, salt tolerance [before growing them in the
field or in glasshouses].
Plants, tissue or isolated cells can be cultured on substrate. If a breeder
wants to select plants for tolerance to a certain substance, that substance (for
example, salt) is added to the substrate.
The breeder then simply waits to see which plants or cells continue to grow
well. The plants that pass this test can then be propagated in vitro. When they
have grown roots and are hardened off, they are ready to be moved to the
glasshouse or open field, where subsequent selection takes place.
