Genetic analysis of the heartwood properties and Genotype x Environment Interaction effect in Castanopsis hystrix half-sib families

Heartwood are mainly used as Castanopsis hystrix valuable wood, which play a vital role in determining the quality of wood for sales, value assessment, and consumption. There are two defects in the heartwood produced by C. hystrix commercial forests: a low proportion of heartwood, reducing the output of high-value wood, and the uneven color of the heartwood from red to reddish-brown, affecting its visual appearance and decorative performance. As these two defects seriously influence the quality of C. hystrix heartwood, breeding of high-yield and high-quality heartwood varieties is critical. The present study examined 20-year-old C. hystrix forests in Yulin, Liuzhou, and Pingxiang counties in China. Through analysis of the proportion, density, brightness L* , chroma a* , and chroma b* of heartwood, genetic variation in each trait was described, genetic parameters were estimated, and the genotype by environment interaction effect was clarified. The average value of the above traits were 34.76%, 0.67 g/cm(3), 52.22, 13.90, and 17.25, respectively. The results of the joint three-site variance analysis reveal that heartwood proportion, density, chroma a* , chroma b* have significant (p < 0.05) or extremely significant (p < 0.01) genotype, environment, and their interaction effects, with family heritability values of 0.25, 0.23, 0.31, and 0.54, respectively. Based on the BLUP-GGE biplot of single and multiple traits, the families with strong adaptability and stable genetics were selected. The average genetic gains in heartwood proportion, density, chroma a* , and chroma b* from families 7, 8 and 9 were 5.83%, 0.02%, 1.04%, and 3.37%, respectively. The three families selected in this study were vital for promotion and utilization, providing a theoretical foundation for the innovation of C. hystrix germplasm and precise improvement of wood quality in South China.