No abstract

No abstract

Genetic variation in nitrogen (N) and phosphorus (P) utilization (amount of total biomass produced per unit nutrient in the needles) and growth traits in seedlings from 30 open-pollinated families of Picea abies (L.) Karst. was estimated. Seedlings were grown under two nutrient regimens: free access to nutrients and restricted access. There was a strong treatment effect on most growth traits. With free access, families allocated relatively more biomass to the stem and less to the roots than they did with restricted access. Heritabilities for growth traits were higher with free access treatment (0.33-0.81) than with restricted access treatment (0.20-0.45). Family variance components for N and P utilization were significant (p < 0.05) with restricted access but not with free access. Genetic correlation between nutrient utilization and height traits with restricted access ranged from none to moderate ( -0.31 to 0.56). Genetic correlations between the same trait assessed in the two treatments were strong for height and moderate for biomass.

No abstract

One of the aims of retrospective early tests in growth chambers is to find juvenile traits that can be used as predictors of future growth. As growth is a complex trait it has been difficult to find a relationship between results from field tests and single juvenile traits measured in the growth chamber. The objective of this study was to analyse whether using a combination of juvenile traits measured in the growth chamber would improve the relationship with traits measured in field trials. Data from four growthchamber experiments and three field trials were used in the analysis. In total 13 different treatments and 134 different traits were studied. The growth-chamber experiments included different temperature, nutrient availability, and watering regimes. The genetic relationships between stem volume in the field trials and a combination of juvenile traits in the growth-chamber experiments were weak, and only a small part of the variation in the field trials could be explained by a combination of juvenile traits from the growth-chamber experiments. In some cases strong relationships were found, but they occurred randomly and appeared to have little biological relevance. The genetic correlations between the same traits measured in nonlimiting treatments in the four growth-chamber experiments were also weak. No strong, consistent juvenile-mature relationships were detected, despite the inclusion of a combination of traits in the analysis. One possible reason for this is that different sets of genes regulate growth at different ages.