2024 journal article
Age Affects Genetic Gain Estimates in <i>Pinus taeda</i> L. Progeny Tests
SILVAE GENETICA, 73(1), 149–159.
author keywords: Loblolly pine; tree improvement; breeding value; age effect; gain adjustment; family deployment
open access via doi.org (publisher)
Source: Web Of Science
Added: November 12, 2024
Abstract In forest tree breeding, genetic gain is often estimated from progeny tests at juvenile ages comparing the performance of specific families against a non-improved checklot. This study evaluated the effects of progeny test age on genetic gain estimates in Pinus taeda L. Growth, disease, and stem quality traits were assessed at ages 4, 6, 8, and 12 years across 103 trials planted in the southeastern United States. Results showed that heritability estimates generally increased with age, particularly for growth traits and stem straightness. Breeding values for height and volume increased over time, with stable rankings, while fusiform rust disease incidence (caused by the fungus Cronartium quercuum f. sp. fusiforme ) remained consistent. Stem straightness exhibited less stability. Mean age-to-age correlations of breeding values were high for height (0.81-0.95), volume (0.76-0.96), and rust (0.81-0.95) but were slightly lower for straightness (0.67-0.89). Genetic gain for volume and straightness showed a significant upward trend over ages for a large number of parents. For height, about half of the parents showed a positive change in gain, whereas for fusiform rust disease, more than half showed a decrease in gain over time. The study underscores the importance of considering measurement age in progeny tests, as it impacts genetic gain estimates and selection decisions. Findings suggest that while early measurements accelerate gain per year in breeding cycles, older measurements for growth and stem quality traits provide more reliable estimates of gain for deployment. The linear relationship between gain estimates from older ages can be used to rescale gains at younger ages.