An advanced-generation seed orchards for Silver fir

Abstract

In Romania, there are 700.9 ha broad - leaved and coniferous seed orchards 92.1 ha of themare Silver fir seed orchards. These are 25 – 30 years old plantations of untested plus trees that requirea testing process of their genetic value in order to advance to the second generation of seed orchards.The most advanced generation seed orchards are based on selections made in full-sib families aftercrosses among members in the first - generation clone seed orchards.This paper presents the results of the researche carried on in Silver fir seed orchards settledon forest districts Adancata, in 1982. Seed orchard consists of 46 Silver fir clones grafted with scionsfrom plus trees selected in 6 regions of provenance. Research focused on the assessment of interclonalgenetic variability, correlations between studied traits, broad – sense heritability, expected genetic gainand full – sib pollination in first - generation seed orchard of Silver fir. Total height, diameter at 1,30m,branches characters, stem straightness and fructification in the year 2007 were the investigated traits.Variance analysis shows a great interclonal genetic variability for all studied traits. Thephenotypic correlations prove the possibility of selection in accordance with many characters. Broad– sense heritability coefficients are 69 % for total height and 67% for diameter at 1,30m and between39 – 62 % for qualitative traits which means high genetic control. Expected genetic gain was estimatedfor two selection methods: direct (by total height, diameter at 1,30m and stem straightness) andindirect selection (by branches characters). An important genetic gain can be obtained by directselection both for growth characters (15%) and stem straightness (13%). Full-sib pollination amongthe best 11 clones, in system half-diallel, was done in order to test genetic value of the clones. Firstgeneration seed orchards are a large genetic base for future selections and have an important role inlong time breeding.