关键词: 湿加松, 测交系, 生长性状, 遗传变异, 遗传参数

Abstract:

Objective: Based on the progeny determination data from genetic design trials involving cross-breeding between Pinus elliottii and P. caribaea, this study analyzed the genetic variation patterns of growth traits in the hybrid pine. The superior parents with high combining ability and hybrid combinations with heterosis were screened, aiming to provide a reliable theoretical basis and material foundation for developing hybrid breeding programs and selecting elite families in P. elliottii × P. caribaea. Method: A total of 27 P. elliottii × P. caribaea families (6 × 5 testcrossing design, with missing 3 combinations) were used as research materials, and the tree height, diameter at breast height (DBH), and wood volume of the 15-year-old trees were measured. The genetic parameters were estimated through analysis of variance. The parental evaluation and selection of superior hybrid combinations were conducted by analyzing combining ability and calculating heterosis. Result: The average values of tree height, DBH, and timber volume of 15-year-old hybrid pines were 18.87 m, 22.64 cm, and 0.42 m³, respectively, with average heterosis of 9.42%, 19.29%, and 87.62%, respectively. There were extremely significant differences in DBH and timber volume among paternal, maternal, and their interaction effects, while tree height only showed significant differences among maternal parents. The heritability for tree height, DBH, and volume was 0.26, 0.29, and 0.27, respectively, indicating moderate genetic control. For tree height traits, the parent interaction was greater than the maternal effect, which was in turn greater than the paternal effect. The general combining ability (GCA) effect exceeded the special combining ability (SCA) effect. For DBH and volume traits, the variance component of the parent interaction was close to the sum of the maternal and paternal effects. The paternal effect was significantly greater than the maternal effect, and the SCA effect exceeded the GCA effect. The paternal additive contribution to DBH and volume was significantly higher than that of the maternal parent, while the maternal parent contributed more to tree height than the paternal parent. The GCA range of the maternal parent for tree height, DBH, and wood volume was –1.2119?0.8338 m, –3.1639?2.2895 cm, and –0.1223?0.1005 m³, respectively, while the paternal parent GCA ranged from –0.8299?0.5333 m, –3.4347?2.3379 cm, and –0.1292?0.1040 m³, respectively. S7 and H3 had the highest GCA, being the optimal maternal and paternal parents, respectively. The SCA ranges for tree height, DBH, and wood volume were –1.6523?1.4606 m, –4.5242?3.6855 cm, and –0.1855~0.1305 m³, respectively. The hybrid combination of S6×H3 had the highest SCA. Five high-yield stable hybrid families were selected based on comprehensive absolute growth, parental combining ability, and intra-family variation, which were S6×H3, S16×H22, S6×H8, S7×H9, and S13×H8, and their average genetic gain of 9.26% in volume and an average better-parent heterosis was 171.78% in volume. Conclusion: P. elliottii × P. caribaea exhibits strong rapid growth potential and high heterosis in the central Guangxi region. The interactions between parental lines exert a greater influence on growth traits than the individual parental effects. The heterosis observed is primarily driven by dominant and epistatic effects, with additive effects playing a secondary role. The maternal parent exerts a stronger influence on tree height growth than the paternal parent, while the paternal parent has a greater effect on radial growth than the maternal parent. The above conclusions provide a reliable theoretical basis for formulating the breeding program of P. elliottii × P. caribaea. Additionally, three key breeding parents of P. elliottii and P. caribaea, and five superior families of P. elliottii × P. caribaea were selected, providing high-quality materials for P. elliottii × P. caribaea breeding and the promotion of superior varieties.

Key words: Pinus elliottii × P. caribaea, tester strain, growth traits, genetic variation, genetic parameter