Physical mutagens, particularly gamma and X-rays, are well established in plant mutation breeding. Although gamma irradiation has been predominant, it involves the use of radioactive isotopes and requires specialist facilities (gamma cells, gamma houses and gamma fields). X-ray machines are more abundant and easier to use, and so are becoming more popular as they do not involve radioactive isotopes and therefore are not governed by the same stringent regulations as gamma emitters. A brief description and comparison of gamma and X-ray irradiation is given. Physical irradiation services are available at the international, regional and national levels. Other non-physical mutagens are discussed in relation to plant breeding and functional genomics.

A brief and general description of mutation breeding is provided. Mutation has been a successful strategy in producing over 3000 mutant cultivars in over 200 crop species worldwide. Oil palm is one of the few major crop species, and the only oil crop not to have been improved by mutation breeding. However, pioneering work in mutation breeding in oil palm did take place in Ghana in the 1970s. This produced the first M1 population in oil palm and has only recently been progressed by developing M2 populations and in discovering mutants for crop improvement.