Sugar beets combinability analyzes throghut two cycles of recurrent breeding

Yield and sugar content genetic analyzes for hybrids developed engaging pollinating lines of the first and the second inbred generations throughout two cycles of recurrent breeding has underpinned the determination of regularities for combinability expression in crossing components and the change of their gene interaction types. This unveiled the lack of correlation between the parents descriptions as selected from groups that displayed contrast combining of productivity components and the lines combinability derived thereof. This provided a ground for correcting the breeding technology of the development of MS hybrids through the exclusion of individual polarization as phenotype based breeding method with replacing this by the assessment of economical value of the topcrossing components. The genetic value was determined for pollinator lines of І1 first hybrid generation by productivity components derived from multiple seed populations by Ulad breeding. 7 economically valuable lines were derived from U752 population by yield and 17 by sugar content, whereas 6 and 10 limes were derived from КМ2, respectively . This provided a ground for the development of synthetic varieties that displayed yield and sugar content characteristics improved, respectively, by 9,4 and 2,4% (U752 initial population ) and by 4,4 and 8,3% ( КМ2 initial population) compared to group standard. The structure of genetic variability of MS hybrids productivity as developed engaging І2 .first and second inbred generation. In the genotype variation of characteristics of hybrids derived from І1 pollinators of recurrent breeding first cycle the additive effects of both parental forms prevailed, and as regards the hybrids developed engaging І2 pollinators of the second cycle of recurrent breeding non-additive effects of the components interaction prevailed. In the second cycle of recurrent breeding 7 І2 lines valuable for combining were singled out, which had high general combinability by yield, and 8 were singled out by sugar content. 5 lines were singled out: U752/5/7, U752/84/3, КМ2/33/4, КМ2/34/7, КМ2/75/4, which combined high general combinability by yield and sugar content at once. Heterosis effect of hybrid combinations was subject to total fusion of additive and non-additive effects of the genes controlling quantitative characteristics of the productivity. The best hybrids yield engaging І2, pollinator lines selected out of U752 and КМ2 multi-seed populations ranged within 104...117,3%, sugar content – 102,4...106,0%, while that of synthetic varieties – 113,4 and 103,6% (U752) and 106,7 and 109,3% (КМ2), respectively, against the group standard.