Qualitative Traits of Norway Spruce [Picea abies (L.) Karst.] Depending on First-Order Branches: Evaluation in Comparative Trials
Notulae Botanicae Horti Agrobotanici Cluj-Napoca
To establish the most important Norway spruce Romanian populations in order to improve the genetic value of future forests, open-pollinated progeny of ten plus trees originating from 33 Norway spruce seed sources were evaluated at the age of 30 years in two field trials established in different site conditions: outside (Avrig trial) versus natural range (Breţcu trial) of Norway spruce in Romania. Evaluations have been made concerning the most important branches characteristics, influencing wood
... quality: Number of branches per whorl, dominant branch insertion angle, dominant branch diameter and branch finesse. Highly significant differences (p<0.001) were found among seed sources in both sites for all of the analyzed traits. The strong populations × localities interaction show the high spruce ability to react to the changing environmental conditions. Near-sites populations were placed in the first half of ranking. Smaller values were recorded in the Avrig trial than in the Breţcu trial for the number of branches per whorl (4.5%) and branches finesse (5.1%). The populations from the Eastern Carpathians stand out by showing sustained growth and superior wood quality, while the populations from the Western Romanian Carpathians generally have smaller differences between the mean values of analysed traits in both field trials. Simultaneous improvement of the spruce following quantitative and qualitative traits pending on the number of branches per whorl and branches diameter is contraindicated. The two-stage selection strategy seems to be applicable in this case.