Influence of the direction of crossing on heterosis and transgression events in relation to the length of the vegetative period of Burley tobaccos variety group

Y. Dyulgerski2, T. Radoukova2*, L. Dospatliev3

1Tobacco and Tobacco Products Institute, Markovo, 4108 Plovdiv, Bulgaria
2Department of Botany and MOB, Faculty of Biology, Plovdiv University “Paisii Hilendarski”, 24 Tzar Assen, 4000 Plovdiv, Bulgaria
3Department of Pharmacology, Animal Physiology and Physiological Chemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria

Abstract. Investigated are manifestations of real and hypothetical heterosis in terms of the length of vegetative period in ten hybrid combinations involving indigenous and introduced varieties of Burley tobacco. Each of them is represented by forward and reverse cross. The results show that more than half of the Burley tobacco hybrid combinations observed significant negative heterosis. Heterozis effect is influenced positively by distance of parents used for hybridization, and the participation of a variety Burley 1344, regardless of whether maternal or paternal component. The direction of crossing influences manifestations of heterosis effect in terms of length of the vegetative period at cross examined Burley tobacco. Heterosis effect is more pronounced when a local variety or line is used as a mother component and an imported variety is used as a father component. Transgressive manifestations in the studied hybrids in the second generation in terms of length of the vegetative period presented by degree and frequency are relatively low presented and do not have great importance for the selection practice. The direction of crossing influences the degree and to a lesser extent the frequency of transgressive events. Strong relationship between manifestations of heterosis and transgression has not been observed.

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Correlations between morphological and productive parameters in Burley tobacco

Y. Dyulgerski1, T. Radoukova2*

Abstract. The dependencies are investigated between important morphological and productive signs of Burley tobacco. Five important Burley tobacco varieties – Burley 1000, Burley 1317, Burley 21, Burley 420 and Pliskaare tested. Strong positive correlation between plant height and number of leaves is established. The number of leaves is positively correlated with yield but negatively with the size of the leaves. The size of the leaves is positively correlated with yield and percentage of classes. The length of the vegetative period is positively correlated with all studied morphological parameters and yield, but negatively with the percentage of first class. The increase in yield is related to the percentage of first class. The results obtained can be used successfully to optimize the selection process in Burley tobacco.

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Comparative morphological study of new burley tobacco lines

T. Radoukova, Y.Dyulgerski
Abstract. The variation degree of the basic morphological characteristics in 15 new perspective lines of the Burley tobacco variety group was established and analyzed. Detailed morphological characteristic of the studied tobacco samples was developed. For the plant height, leaf number and size, the differences between the studied lines are in statistical error, which is an indication of breeding success. The highest variability of the descriptive characteristics was established for the flower panicle width and the size of the leaf auricle). Referring to descriptive characteristics, the greatest diversity in the studied lines was reported for the shape and surface of the leaf blade, as well as for the angle of leaf divergence from the stem. The developed morphological characteristics showed that all the studied lines had optimal quantitative and qualitative characteristics complying with the requirements to Burley tobacco variety group.

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