Selection procedures with perennial, vegetatively propagated crops

Using tree fruit as an example the paper describes the procedures for the selection of mutants useful in commerce without further hybridization, from a mutagen-treated population. Similar considerations will apply to most other vegetatively propagated crops. The main points covered are the need for disease-free high-quality starting material and the choice of selection procedures at the MV2 (second vegetative generation after treatment). To display the slight mutations that tend to be the most useful it is necessary to ensure very uniform nursery growth of this selection population. Further selection is made in replicated trials, followed by an extra stage, not necessary in seed-propagated crops, to identify the periclinal chimaeras that produce unstable clones. These are identified by testing samples using a second radiation treatment. (author)