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Soil drought is among the serious problems in agriculture leading to considerable losses of crop production. Tobacco is important industrial crop, which is relatively sensitive to water deficit, and the selection of drought resistant varieties is of particular interest. In line with this, we examined the drought tolerance of three genotypes of flue-cured Virginia tobacco-cv. Coker 254 (American origin), line L 825 (Czech origin), which are introduced in Bulgaria, and their hybrid cv. Virzhinia 0514, which is certified as Bulgarian standard. The content of stress biomarkers malondialdehyde, hydrogen peroxide and free proline as well as some morphometric traits were assessed in plants subjected to three levels of drought. The results showed that the three tested tobacco genotypes were moderately tolerant to drought. These data can be used for selection and development of new genotypes with improved tolerance to soil drought. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the impact of morphological traits on the yield of Virginia tobacco lines with consolidated complex resistance to economically important viral diseases, Tobacco mosaic virus and Potato virus Y. The effect of the change in the height of the plant, the number of leaves, the sizes of the sixth and twelfth leaves on the yield is studied. Correlation analysis, regression analysis and Path analysis were applied. The direct and indirect influence of the studied traits on the yields is determined. The calculated correlation coefficients show a very strong, positive correlation between the yield and the length of the sixth leaf (0.985 **), the width of the sixth leaf (0.949 **), the number of leaves (0.934 **), the length (0.970 **) and the width of the twelfth leaf (0.966 **). In L 5, the length of the sixth leaf and the width of the twelfth leaf have a very strong direct effect on the yield. In L 6.3.3, the number of leaves and the length of the sixth leaf have the highest direct effect on the yield. [ABSTRACT FROM AUTHOR]