Assessment of polymorphism by growth of half-sibs Pinus sibirica Du Tour offspring of 19-year-old biological age

Relevance. Breeding studies on testing the seed offspring of valuable forest-forming breeds of the Russian Federation are of great practical importance and become even more relevant during the transition to intensive forest cultivation and the introduction of genetic methods in forestry. The purpose of this work was to assess the level of variability in the growth of the half-sibs offspring Pinus sibirica Du Tour at the age of 19 years. Methods. The growth of half-sibs offspring of Siberian cedar of 19-year-old biological age has been studied. Studies were carried out in experimental cultures of the educational and experimental forestry enterprise of Siberian State University named after M.F. Reshetnev. This territory, according to forestgrowing zoning, belongs to the Central Siberian sub-taiga-forest-steppe region. In half-sibs offspring obtained from free pollination of maternal plants of different geographical origin, the height and diameter of the trunk were studied 5 cm from the surface of the earth. An index score of offspring was used to assess overall combinational ability. Results. The results of the study showed manifestations of polymorphism in the growth rate of semiSiberian cedar offspring of Siberian 19-year-old biological age. It is obtained from the free pollination of mother plants of different geographical origin and forms growing in plantation crops. Significant differences in height and stem diameter at the root neck were noted, depending on the initial origin of the parent trees and the composition of pollinators. It is noted that, regardless of the combination of genes, the semi-hybrids of the mother trees of the Tisulsky, Cheremkhovsky, Tansybeysky, Altai, and local (Biryusinsky) genotypes maintain a high growth rate. The maternal trees of the Leninogorsk population (Republic of Kazakhstan) were distinguished by a weak general combinational ability. The conducted index assessment of the offspring over two years of observation allowed us to confirm the noted patterns in the manifestation of signs of maternal plants in terms of growth rate and to isolate some of them, characterized by high combinational ability. In general, there is a high polymorphism and differentiation of families in terms of growth rate.