Efficiency of different cycles of multiple individual-family selection in the breeding of multi-sprout sugar beet pollinators

Abstract

Purpose. To create multi-sprout sugar beet pollinators with a narrowed genetic basis, to assess their productivity and combining ability over time at different stages of multiple individual-family selection.

Materials and methods. The studies were conducted at the Tobacco Experimental Station of the National Research Center «Institute of Agriculture of NAAS» in the Laboratory of Sugar Beet Breeding in 2009–2020. Seven diploid multi-sprout sugar beet populations bred in Ukraine were taken as starting material. New multi-sprout pollinators were obtained by multiple individual-family selection. Breeding accessions were tested by the method developed by scientists of the Institute of Bioenergy Crops and Sugar Beet of NAAS. The GCA was evaluated using unidirectional cyclic crosses on the basis of three CMS-testers.

Results and discussion. The results demonstrated a high efficiency of two and three cycles of individual-family selection for increasing the root yields of the multi-sprout sugar beet pollinators. The root yields increased by 11.7% and 13.5% after two and three selection cycles, respectively, related to the original populations. Subsequent selection cycles (four and five) were less effective due to inbreeding depression. The yields of the multi-sprout pollinators was 106.3% and 98.2% after four and five selection cycles, respectively, related to the original populations. The multi-sprout pollinators from selection cycles four and five had the highest sugar content in roots: 121.6% and 119.5%, respectively, related to the original populations.

As to the compound trait of «sugar collection», the highest productivity in the multi-sprout pollinators was observed after three selection cycles (119.5%). In subsequent cycles of selection, this parameter decreased.

The yield and sugar content in roots of the best diploid multi-sprout sugar beet pollinators varied between 108.2–116.3% and 98.6–105.5%, respectively, related to the group reference. As to the sugar collection and output, they exceeded the group reference by 9.2–19.2% and 9.5–21.8%, respectively.

Conclusions. In the 2009–2020 studies, the changes in the performance characteristics of the multi-sprout sugar beet pollinators from different cycles of multiple individual-family selection were investigated over time. The highest basic productivity was seen in the multi-sprout pollinators from selection cycle 3, which should be used both as sources of valuable genotypes – ancestors of lines and directly as parents of hybrids. Ten highly productive multi-sprout sugar beet pollinators with the optimal combinations of the most significant breeding-genetic traits have been created.