Early selection: how early is early enough? Part 4

In the previous post we were able to screen trees for wood properties at 2 years of age, separating normal and compression wood by leaning the trees. We obtained genetic parameters, breeding values, etc. However, we also discovered that planting the trees directly in the ground was still subject to too much environmental variability. So, take a guess… we planted another trial.

This time we had 90 families and 10 clones, for a total of 3,000 trees growing in 75 litre bags, leaning, with slow-release fertiliser, an irrigation system. Not only that, but we tested 3 different populations: clonal (derived from trees selected at ‘traditional’ 8 years of age for growth and stiffness), seed orchard (derived from trees selected at ‘traditional’ 8 years of age for growth and basic density), and new selections (selected for a combination of traits).

As a start, heritabilities increased substantially (sometimes doubling it), which is not surprising considering that the trees were in bags. One cool thing was that we could observe differences between populations at 2 years of age; so selecting at ‘traditional’ 1/4-1/3 of rotation does actually pick up trees on different wood properties trajectories. This was 1- confirmation of something we hinted some years ago (coming post) and 2- guiding other work I am writing up at the moment.

This “bagged trial” was published Open Access as: Apiolaza LA and Sharma M. 2023. Selection history affects very early expression of wood properties in Pinus radiata. New Forests DOI: 10.1007/s11056-023-09997-3.