Savina O. Theoretical foundation and practice of the breeding process with tobacco (Nicotiana tabacum L.)

The thesis presents theoretical foundation and experimental realization of new approaches to solving the problem of increasing productivity of new tobacco varieties, enlarging assortment of proposed products, improving technological properties and reducing their toxicity. The most impotant characters and properties which play a leading role in the formation of tobacco quality and in provision of adaptive potential are established; the possibility of their combination in hybridization is investigated. On the basis of detailed ecological investigations thresholds of potential productivity of new tobacco varieties and hybrids and ways of its realization are established. A new type of tobacco is created morphological characters of which significantly differ in drought and disease resistance; this type will serve as a source of valuable traits in breeding. Relationship among principal properties is scientifically proved which was laid as a foundation of a variety model within the limits of variety-types andprinciples of selection for productivity. On the basis of elaboration of principles of using induced apomixis, the breeding process is shortened, a method of heterosis fixation is worked out and a scheme of primary seed production with the aim of quick and qualitative introduction of new varieties and hybrids into production is improved. The novelty of methods of breeding elaborated by the author and of developed varieties is proved by 6 author's certificates for tobacco varieties and by 9 author's certificates for valuable samples which are registered in the National genetic fund of Ukraine.