Matti Haapanen. (2024). Realised genetic gains from past Finnish silver birch seed orchards. Silva Fennica vol. 58 no. 1 article id 23072. https://doi.org/10.14214/sf.23072

Keywords: Betula pendula; seed orchards; genetic gain; forest reproductive materials

Highlights: Seed orchard materials generally outperformed unimproved trees in all growth and quality traits, but individual seed orchards showed substantial performance variability; Realised gains in stem volume and forking showed an increasing temporal trend, whereas gains in branch quality were positive and steady; Gains in stem volume and branch quality trade off slightly; The bi-clonal seed orchard variety “JR-2” emerged as the best overall performer across all the seed orchards, whereas the older variety “JR-1” was mediocre; An alternative statistical concept, D-value, was introduced to compare levels of genetic gains for different scaled, normally distributed traits.

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Genetic gains realised through silver birch (Betula pendula Roth) seed orchards were studied using data from common-garden trials established at 34 sites in southern and central Finland. The test materials include seedlots representing 19 commercial seed orchards that operated between 1972 and 2009, and 21 natural stands. All the trials were assessed for several growth and quality traits between the ages of 9 and 24. Realised gains were estimated based on univariate linear mixed models with corrections for latitudinal seed transfer effects. Overall, seed orchard materials outperformed unimproved reference materials in all the traits but results for individual seed orchards varied substantially. Stem volume gains ranged from 1.0% to 31.1%. Improved trees had, on average, 6.8% (up to 26.7%) fewer ramicorn branches and 16.2% (up to 57.6%) fewer forks than unimproved trees. Branch and overall quality showed consistently positive gains. More recently established seed orchards performed better than older ones, and seed orchards with fewer clones outperformed those with dozens of clones. "JR-1" and "JR-2" bi-clonal seed orchards fared differently, with "JR-1" showing modest genetic gains and "JR-2" emerging as the top overall performer across all seed orchards. An alternative statistical concept, the D-value, was utilised to assess the magnitude of genetic gain for different scaled, normally distributed traits. Average D-values implied a similar level of improvement for stem volume, branch quality, and forking, and a smaller gain for stem slenderness and the number of ramicorn branches. The results for individual seed orchards suggest a slight trade-off between stem volume growth and branch quality.

Haapanen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland https://orcid.org/0000-0003-3294-501X E-mail: matti.haapanen@luke.fi

article id 10534, category Research article

Matti Haapanen, Seppo Ruotsalainen. (2021). Adaptive performance of genetically improved and unimproved seedlings of Scots pine. Silva Fennica vol. 55 no. 5 article id 10534. https://doi.org/10.14214/sf.10534

Keywords: Pinus sylvestris; cold hardiness; growth rhythm; seed orchards; bud set; freezing test; reproductive materials

Highlights: We studied the variation in adaptive traits in one-year-old seedlings of Scots pine representing different levels of genetic gain and geographical origins; All the adaptive traits analyzed showed clinal co-variation with the latitude of origin; Differences in adaptive performance between genetically improved and unimproved reproductive materials were mostly small and insignificant when the effect of the latitudinal origin was considered; First-generation seed orchard materials implied slightly poorer autumn frost hardiness compared to other materials, but the results were ambiguous.

Abstract | Full text in HTML | Full text in PDF | Author Info

Our main objective was to determine whether various genetically improved reproductive materials of Scots pine (Pinus sylvestris L.) differ in growth rhythm, autumn cold acclimation and resilience from unimproved materials. The study consisted of two successive indoor experiments with Scots pine seedlings representing four levels of genetic gain (unimproved natural stands, first-generation seed orchards, 1.5-generation seed orchards and seed orchards established with freezing-tested parents) and a wide range of geographical origins within Finland. The seedlings were assessed for terminal shoot elongation, growth cessation, bud set, freezing injuries and bud flushing over the first growth period. All the adaptive traits showed a latitudinal trend regardless of the genetic level. Seed orchard progenies and natural stand progenies did not differ significantly in the timing of growth cessation, bud set, and the flushing rate of the frost-injured seedlings, after the trait variation was adjusted to the latitude of origin. The differences in autumn frost hardiness were insignificant, too, except for the somewhat higher injury rate displayed by the first-generation seed orchard materials. The finding was not conclusive due to ambiguous results from the two experiments. Overall, we did not find evidence of alarming compromises in the adaptive performance of genetically improved materials.

Haapanen, Natural Resources Institute Finland (Luke), Production systems, Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0003-3294-501X E-mail: matti.haapanen@luke.fi
Ruotsalainen, Natural Resources Institute Finland (Luke), Production systems, Vipusenkuja 5, FI-57200 Savonlinna, Finland https://orcid.org/0000-0002-2547-0282 E-mail: seppo.ruotsalainen@luke.fi

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