Spontaneous and induced mutations in the trees and shrubs of Serbia and their usability value

Mutations include the changes of the inherited material and they occur naturally, but very rarely. This paper presents the spontaneous and induced mutations, their frequency of occurrence and applicability for the needs of plant production in forestry. The initial material includes the trees and shrubs of Serbia, and the methods are the comparative morpho-physiological analysis, ionising radiation and chemical half-sib tests Spontaneous mutations in our country have been recorded more frequently since the sixties and the study of intra-variability of trees and shrubs in Serbia has been intensified. They include the changes of growth habit, character of increment, abnormalities in the structure of vegetative and generative organs. By selection and vegetative propagation, numerous ornamental tree and shrub varieties have been synthesised over a more or less long period. After the discovery of the vigour of triploid mutants trees, their mass production has been elaborated: by crossing triploid and diploid trees By the treatment of the reproductive material by ionising radiation (UV, gamma rays, terminal neutrons), and chemical materials, the frequency of mutations increased drastically, especially with higher doses up to 100% in the treated organisms. The mutants have, as a rule, reduced growth elements, reduced adaptation, and when selected and propagated vegetatively, they ensure a rich initial material for the synthesis of numerous ornamental cultivars of trees and shrubs. The method of radiation breeding is the most promising for the improvement of ornamental plants, while mass production of triploid mutants is the only method used in the improvement of forest trees.