Retrospective genetic testing ofPicea abiesunder controlled temperature and moisture regimes

A retrospective early test of Picea abies (L.) Karst. was conducted under two temperature ("high" and "low") and two irrigation ("well-watered" and "drought") regimes. Height, dry mass, and phenological traits were assessed for seedlings from 36 open-pollinated families grown in a growth chamber for two growth periods. The attributes measured were compared with the growth traits of three 24-year-old field progeny trials propagated from the same parents. Heritabilities for biomass and height were mainly moderate to strong (0.1–0.8) in the well-watered treatments, while they were weaker in the drought treatments (0.0–0.5). Juvenile-mature (J–M) genetic correlations for growth traits were generally weak. There were, on average, stronger J–M correlations in the drought treatments than in the well-watered treatments. Similarly, there were stronger J–M correlations in the high- than in the low-temperature treatment. The results suggest that genotype × environment (G×E) interaction between the juvenile and mature environment is one of the reasons for low J–M correlations. This supports the hypothesis that higher J–M correlations can be obtained by mimicking natural growth-limiting factors in the juveniles' growth chambers. We conclude that further development of more efficient early selection methods for P. abies should include periodic drought and the development of optimal temperature regimes.