Plasticity and stability of hybrid aspen clones in 14 field trials over Sweden, Finland and north-west Russia

The study aimed at estimating the genotype × environment (G × E) interaction, stability and plasticity parameters for height growth and survival of hybrid aspen (Populus tremula L. × Populus tremuloides Michx.) clones. A set of 17 hybrid aspen clones were studied at age four in 11 field trials (series 1) and a set of 12 clones were studied at age 12 in three field trials (series 2) in Sweden, Finland and north-west Russia. There was an intermediate and significant correlation between height ranks at four and 12 years, showing modest G × E interaction for tree height. The corresponding correlation for survival was weak and insignificant, indicating a stronger G × E interaction than for height. The stability parameter (S) for height showed large differences among clones. The plasticity index (PI) values for height ranged from 0.6 to 0.8 among clones, demonstrating high levels of phenotypic plasticity.