Testing of the narrow crowned Norway spruce ideotype (Picea abies f. pendula) and the hybrids with normal crown form (pyramidalis) in multisite comparative trials

Abstract The study aims to analyse the stability of the narrow crowned Norway spruce ( pendula form) compared to the normal spruce form ( pyramidalis form) and the hybrids of the two forms, in 5 field trials (Comandău, Lepsa 1&2, Ilva Mică and Voineasa) located in the Romanian Carpathians. Trees height (Th), breast height diameter (Dbh), height growth of the last year, crown diameter (Cd), number of branches per whorl (Nbw) and dominant branch diameter (Dbd) traits were measured and survival rate (Sr) was determined, at 20 years old. Also, branches finesse (Bf), trees volume (Tv) and trees slenderness (Ts) were calculated. In order to compare the wood density (Cwd) there were collected cores. In all trials ANOVA revealed significant (p  pendula trees present higher values for Sr, Dbh and Tv, and lower values for Ts, Cd, Nbw, Dbd and Bf, compared to pyramidalis spruce form, which showed a higher stability. Heritability was in generally low (h 2 pendula form in Lepsa trial, while in Comandău trial the pyramidalis registered a higher value (7%). In the new breeding programme, the selection strategy may be pursued with the pendula trees selection based on Ts and branches traits.