Inheritance of height growth and autumn cold hardiness based on two generations of full-sib and half-sib families of Pinus sylvestris

Abstract

The genetic variability in height growth and autumn cold hardiness were evaluated in a full-sib family of Scots pine (Pinus sylvestris (L.)) in a field trial in northern Sweden and 358 open pollinated families generated from the progeny of the full-sib cross. Height and autumn cold hardiness were assessed in the progeny of the full-sib cross at 9–19 years of age and on 3995 open pollinated progenies at three years of age. The autumn cold hardiness [critical temperature (CT)] of trees and progenies was tested by artificial freeze testing of detached needles at various temperatures. Significant genetic variation was found among progenies in both height growth and cold hardiness with a narrow sense heritability of 0.16 and 0.37, respectively. There was also a significant positive genetic correlation (r _a =0.39) between height growth and CT with taller trees showing later autumn cold acclimation. It was concluded that there is significant additive genetic variance for height and CT which warrants a potential for mapping quantitative trait loci. Furthermore, the low heritability for height growth shows the importance of removing the environmental influence by using additive genetic predictions instead of phenotypic measurements thereby improving the accuracy of genetic associations.

Keywords:

• Cold hardiness
• freeze testing
• full-sib family
• genetic variation
• height growth
• Scots pine

Acknowledgements

We are indebted to the staff at Skogforsk in Sävar who has established the field trials. We are also grateful to Ken Keefover-Ring for his linguistic help. The work was supported by the Knowledge Foundation, the Kempe Foundation and The Swedish Tree Breeding Association through the Research School Forest Genetics and Breeding at The Swedish University of Agricultural Sciences.