According to National Forest Inventory data forest land area has increased by 1.9% (125.000 ha) in Lithuania. Softwood deciduous forest land increased most, especially areas of birch species, followed by aspen and black alder. Scots pine stands occupy 35.3%, birch – 22.2%, black alder – 6.8% (statistics year 2011). It is pointed out in the National Forestry Sector Development Programme that up to 70 percent of all forest reproductive material has to be raised using seeds from second generation or higher-level seed orchards. Intense use of established field test trials of forest tree species for breeding purposes becomes very important in this context. Scots pine, silver birch and black alder halfsib families of plus trees were tested for wood hardness in the series field trials at ages 30, 13 and 13, accordingly. The trials consist of 7 populations and 140 families of Scots pine, 24 populations and 100 families of silver birch, 17 populations and 85 families of black alder. Wood hardness was tested by using Pilodyn 6J. Mean value of Pilodyn pin penetration for pine families was 19.3 mm, for silver birch – 23.4, for black alder – 22.0. The average difference between family mean estimates for pine was 4.5 mm, for silver birch – 4.0, for black alder – 4.2. The same complex selection index was used for each species, including wood hardness, height, diameter, stem straightness, branch quality and survival estimates. Height was given an economic weight of 1.5 and wood hardness – 1.3. Such index and selection of the best 15 families and 30 trees in selected families for the higher-level seed orchards are typically used in practical breeding work in Lithuania. Wood hardness and tree height traits were the most heritable. Individual heritability for Scots pine wood hardness was 0.30 and family heritability was 0.65. For silver birch similar estimates were 0.61 and 0.75, for black alder – 0.78 and 0.86. The average genetic gain from all provenance regions in wood hardness (when selecting 15 best families) was estimated for Scots pine 0.5%, silver birch – 3.1%, black alder – 4.8%. The same estimates of genetic gain when selecting 30 best trees in selected families were: 1.6%, 5.7% and 7.4%. If only height and wood hardness were used in calculation of breeding values, then genetic gain for the last trait would be 1.5-2.0 times higher.
Gene resources conservation and forest tree breeding is joint in Lithuania. Study results indicate that it is economically adjusted to start diversified breeding in some widespread conifers and broadleaves.
Keywords: Wood hardness, Genetic gain, Breeding
Authors
Baliuckas V.
Lithuanian Research Centre for Agriculture and Forestry, Institute of Forestry, Department of Forest Tree Genetics and
Breeding, Girionys, Lithuania
Login to download the PDF