Farm Forestry New ZealandEvaluation of genetic gain trials in Douglas-fir
By Jaroslav Klapste, Toby Stovold, Peter Bird, Kane Fleet, March 2023.
Download SWP-T162 (pdf)
Executive summary
The field experiments for the evaluation of realised genetic gain were established in 2012 and 2013 across New Zealand and measured for productivity and stem-form attributes in 2022. We have performed a statistical evaluation to compare the performance of seed sources that are commercially available in New Zealand. The experiments were designed to evaluate not only the differences in genetic quality of the seed lots but also the impact of silvicultural treatments in terms of initial stocking. The data exploration did not find any impact of silvicultural treatments on the investigated traits, most likely due to the young age of the trees. We would recommend re- evaluation of this experiment at a later age.
In terms of productivity, the seed sourced from the Fort Bragg provenance performed best in the North Island, while the California and Washington provenances performed poorly, presumably due to a short growth season in Washington or susceptibility to Swiss needle casting in the California provenance. On the other hand, seed sources from Fort Bragg provenances performed poorly in the south of the South Island, which might be attributed to a mismatch between phenology and climatic conditions, which may cause late frost damage. The seed sources based on selections from Oregon and Washington provenances showed superior performance in the south of the South Island, while seed sources based on selections from California and Washington provenances worked best in the north of the South Island. The material from the Washington seed stand performed the poorest.
In stem form traits, the seed sources based on selections from Ashley, Oregon, and Fort Bragg showed superior performance for stem form attributes in the North Island, while the seed sources based on selections from California showed the worst. Even in northern South Island (Blenheim), the seed sources based on Ashley provenance were excellent. Similar to productivity, seed sources based on selections from California provenances were superior in stem form attributes due to the lack of Swiss needle casting. The seed sources from Tyrell SO and Washington seed stands performed the worst in South Island stem form traits.
In terms of acceptability, the seed sources based on selections from Fort Bragg, Oregon, and Ashley provenances had the highest general acceptance on the North Island, while the selections from Tramway and Californian provenances had the lowest. In the South Island, the seed sources based on selections from Ashley, Fort Bragg, and California provenances had the highest acceptability in the north, and the seed sources based on selections from Fort Bragg and Washington provenances had the highest acceptability in the south. The seed sources from Washington Seed Stand and Tyrell SO had the lowest acceptability on the South Island.
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