Often the comment on mutation induction of vivo material is that the plant material after treatment does not grow. Quite understandable. The tissue is damaged so much that root formation or germination takes too much time and the treated material dies due to environmental factors.
For the generation of mutants tissue culture material is the ideal source. For either chemical or radiation treatment the material is small, soft and uniform which makes it easy to treat.
A second advantage of tissue culture material is the fact that after the treatment the meristems are given time to recover from the treatment in the sterile environment. Often treated shoots or axillairy buds do not root but after a growing period in the lab the newly formed plantlets can be rooted easily.