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Evaluation of Douglas-fir progeny test FR508/1 and FR508/2

By Jaroslav Klápste, Toby Stovold, Kane Fleet, Peter Bird, March 2023.

Download SWP-T161 (pdf)

Executive summary

Scion’s Douglas-fir breeding program is continuing in genetic improvement of traits related to productivity and stem form by establishment of new generation of progeny trial. The latest generation of progeny test was established in 2011 and recently measured for standard traits at age of 10 years on two sites (Kaingaroa and Gowan Hill). Kaingaroa shows higher level of plant survival compared to Gowan Hill site. Due to extreme weather in 2016 (heavy snowstorm), it has more stem form issues, such as multiple stems. We assume this extreme weather event enhanced stress at this site, reducing additive genetic variance and heritability. California (including Fort Bragg) and Washington had the most affected provenances, whereas NZ Ashley had the least.

Gowan Hill has greater mean diameter at breast height (DBH), stem straightness (STR), stem malformation (MAL), and acceptability (ACC) but also branching quality (BRH) which is undesirable, compared to Kaingaroa. The ability to estimate larger additive genetic variation and heritability allowed for more accurate breeding value, which can lead to more precise expected genetic gain. Surprisingly, spatial analysis by first-order autoregression did not increase genetic parameters, and we may infer that the experimental design is adequate to capture environmental variability at this time (age of 10 years).

Phenotypic data correlation analysis showed two clusters of connected traits: DBH, HT, and BRH, and STR, MAL, and ACC. The patterns in genetic corelations verified these groups. Due of limited genetic components in Kaingaroa, this validation was only done for Gowan Hill trials. STR and DBH are connected with separate clusters, although they can be improved simultaneously due to a 0.27 genetic corelation.

The most productive families at Gowan Hill were from California, Ashly, and Fort Bragg. The unfavourable genetic correlation between DBH and BRH will require selection of correlation breakers to select individuals with above-average DBH and below-average BRH. In stem straightness and malformation, the top families were from Washington and Oregon. Best- performing families in Kaingaroa were from California, NZ Ashley, and Fort Bragg. Again, search for correlation breakers will be required to make genetic improvement in both DBH and BRH simultaneously. Stem straightness was highest in Fort Bragg, Washington, and Oregon, whereas malformation was best in California.


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