COMBINATION ABILITY OF SOYBEAN VARIETIES BY PRODUCTIVITY IN TOPCROSS CROSSES

Two-tester analysis of topcross crossings of soybean varieties, which differ in valuable economic traits and ecological and geographical origin, was used in the research. According to the indicators of combining ability, the value of soybean varieties was determined by the elements of the crop structure. In hybrid populations, the degree and frequency of positive transgressions have been determined, which is a selection material for the creation of new varieties by hybridization. High effects of ZKZ on plant height and attachment of lower beans were established in Sawyer 2-95 variety and KiVin tester; by the number of productive nodes - in the varieties Sawyer 2-95, Medea, Kyivska 97 and tester KyVin; according to the number of beans per plant - in varieties Ustya, Kyivska 97 and tester KyVin; according to the number of seeds on the plant - in the Medea, Kyivska 97 and Hoverla tester varieties; by the weight of 1000 seeds - in varieties Sawyer 2-95, Kyivska 97 and Hoverla tester; according to the mass of grain from the plant - in the varieties Medea, Kyivska 97 and tester Hoverla; in terms of productivity - in Medea, Kyivska 97 and tester Hoverla varieties. It was established that additive effects of genes were dominant in the genetic control of plant height traits and attachment of lower beans, elements of crop structure and productivity, but there was also a significant non-additive effect. According to the number of beans per plant, the number of seeds per plant, and the weight of seeds per plant, in the vast majority of hybrid populations, inheritance by the type of overdominance and dominance of the parental form with a higher manifestation of the trait was noted. The analysis of dominance indicators made it possible to identify crossbreeding combinations that are distinguished by the overdominance of the specified traits and have significant breeding value: Sawyer 2-95 × Hoverla, Kyivska 97 × Hoverla, Kharkivska precocious × Hoverla, Sawyer 2-95 × KiVin, Kharkivska precocious × KiVin.