The dissertation presents the results of research into the nature of inheritance and variability of growth and reproduction characteristics of clones of Scots pine superior trees and their offspring, and identification of best individuals to ensure forest plantations with seed material of improved genetic properties.
Influence of a superior tree (ST) clone ramet nutrition area on the ramet cone production was studied on 2 clonal seed orchards. Clones with a nutrition area of 120 m2 per ramet had on average 1.7 times more cones than clones with a nutrition area of 64 m2 per ramet.
Long-term observations have shown that the phenological development of early and late Scots pine clones on a forest seed orchard depends on the dynamics of accumulation of effective temperatures in a particular year. The shortest difference between the beginning of bud development in early and late clones is 3 days, the longest one is 8, and the average is 5. Variation of the average sums of effective temperatures for the beginning, peak and end of the pollen release is bigger in early clones (CV=10.0 %; 9.4 %; 10.5 %, respectively) and less in late ones (Cv=8.4 %; 7.2 %; 9.7 %). For each next subsequent phase, the difference between early and late clones decreases due to higher effective daily air temperatures. Clones with high and medium intensity of growth, a high and medium intensity of "blooming" and yield of cones are the most promising for seed orchards establishment. According to our long-term data, 60.4 % of the studied clones belong to this category.
Progeny tests (PTs) of the superior trees showed that in the PT-1981 at the age of 22 years, on average, 94.7 % of the offsprings have faster height growth than the standard variant; in the PT-1989, at the age of 20, 50.0 % and 68.2 % of the offsprings grow faster than the standards 1 and 2 respectively; and in the PT-1990, at the age of 19, 76.9 % of the offsprings in the first section and 94.1 % ones in the second section were growing fasten that their standards. For diameter, all progenies were growing faster than the standard variant in the PT-1981; 9.1 % and 63.6 % offsprings performed better than the standards 1 and 2 respectively in the PT-1989; and in the PT-1990, only 1 offspring performed better than the standard in the section 1, and 94.1 % of progenies were better in the section 2. On the basis of the progeny testing, 18 out of 43 STs (41.9 %) were selected as candidates for the elite in terms of general combining ability (GCA).
In all the progeny tests, the crown projection diameter had the highest variability (СV=35.0-44.8 %); the tree height had the lowest variability (СV=12.3-24.8 %). The h2 inheritance coefficients for height in 19-, 20-, and 22-year-old progenies were 0.402, 0.391, and 0.145, respectively, which may reflect the increasing competition in the stand at the pole stage. The h2 coefficients for diameter were insignificant: 0.002, 0.002 and 0.053, respectively. The sib progenies of clones №№ 22, 36, and 54 had on average 14.9 % higher trunk quality than half-sib ones, and 2.4 times more trees of the I and II breeding categories, which may be due to the influence of male parents on the trunk straightness in the offspring; this effect may enable selection for the trunk quality traits in controlled crossings.
In clones with yellow and yellow-pink microstrobili, descendants with yellow microstrobili predominate (89.2 % and 80.8 %, respectively), descendants with yellow-pink ones composed 10.8 % and 15.4 %, respectively. The pink color appeared in half-sib progenies of clones with yellow-pink microstrobili (3.8 %). All sib and half-sib progenies of clones №№ 22, 36 and 54 inherited the yellow color of the maternal clones (100 %).
