SYSTEMATIZATION OF NICOTIANA RUSTICA L. VARIETAL DIVERSITY FOR OPTIMIZATION OF THE BREEDING PROCESS AND CLASSIFICATION OF VARIETAL TYPES

Abstract

The aim of the study is to systematize the varietal diversity of Nicotiana rustica L. in order to enhance the efficiency of the breeding process, preserve the genetic resources of the crop, and create a unified classification to facilitate the selection of parental pairs and the introduction of new varieties into production. A comprehensive approach was used, including morphological evaluation of collection samples of rustic tobacco from different regions (Ukraine, Northern Black Sea region, Europe, Africa, Asia), analysis of economically valuable traits (plant height, leaf shape and size, stem structure, vegetation period duration, yield, and raw material quality), identification of ecotypes, and grouping of varieties by varietal types. The classification by Goodspeed and an ecological-geographical approach were applied for typification. Methods of comparative morphology, statistical data processing, and expert assessment were used. It was found that most modern varieties of rustic tobacco are selected forms of local populations that have high adaptability to regional growing conditions. Foreign varieties have limited practical value for production in Ukraine but are valuable donors for hybridization. For the first time, two main ecotypes of N. rustica L. – northern and southern – are systematically described, which differ significantly in morphological and biological traits as well as in the type of raw material. The northern ecotype is characterized by a short vegetation period, a tendency to produce side shoots, and the use of both leaves and stems, whereas in the southern ecotype, the main product is leaves. A classification of varietal types is proposed based on morphological features, vegetation period, yield, raw material quality, and adaptation to growing conditions. Seven main groups of varietal types are identified, reflecting the geographical and historical formation of the crop’s diversity: Northern Black Sea region, Ukrainian, Western European, Northern European, African, Eastern, and Indian. Analysis of morphological indicators (number of leaves, plant height, vegetation period duration) revealed significant variability among varieties, which creates broad opportunities for targeted selection of parental pairs and the creation of new high-yielding and stress-resistant varieties of rustic tobacco. Of particular value are varieties with the trait of low side-shoot formation, which was obtained through hybridization of local and foreign forms and does not occur in natural populations of N. rustica. Systematization of the varietal diversity of Nicotiana rustica L. by ecotypes and varietal types is an effective tool for improving the efficiency of breeding work, ensuring stable yield and product quality, and preserving the unique genetic pool of the crop. The proposed classification simplifies the procedure for selecting varieties for breeding, increases the efficiency of introducing new varieties into production, and promotes the further development of rustic tobacco cultivation in Ukraine.