GENETIC RELATIONSHIP BETWEEN NURSERY AND EARLY FIELD GROWTH PERFORMANCE IN AN Eucalyptus pellita × E. grandis HYBRID CLONAL POPULATION

HANAR PRASETYO AJI, Dr. Ir. Sapto Indrioko, S.Hut., M.P., IPU. ; Makobatjatji Mmoledi Mphahlele, Ph.D.

2025 | Tesis | S2 Ilmu Kehutanan

Early selection of superior genotypes is critical in Eucalyptus hybrid breeding programs to accelerate genetic gain and enhance resource efficiency. This study investigates the genetic relationship between nursery phenotypes and early field growth performance in a hybrid clonal population of E. pellita × E. grandis. A total of 623 hybrid clones were assessed for seven nursery traits: seedling height, collar diameter, leaf number, branch number, main root number, root quadrant, and root dry weight. Following on, field performance was evaluated at 12 months for height, diameter at breast height, and volume. Genetic parameters were estimated using Best Linear Unbiased Prediction (BLUP), Pedigree-based BLUP (ABLUP), and Single-step Genomic BLUP (ssGBLUP), with Principal Component Analysis (PCA) used to reduce phenotypic dimensionality. Multivariate mixed models and Spearman rank correlations were applied to explore trait relationships across pedigree hierarchies and species contributions. Results demonstrated strong correlations between root and shoot traits, with PCA identifying key axes related to seedling vigor, root architecture, and canopy structure. Incorporating genomic data into ssGBLUP models improved genetic parameter estimation, highlighting the impact of non-additive genetic variance. Multivariate analysis revealed strong correlations within nursery traits and moderate correlations between nursery and early field traits. Spearman rank analysis showed that root-related traits, particularly in E. grandis, were strongly linked to field performance, while E. pellita exhibited trade-offs between certain traits and field growth. Gradient boosting machine analysis confirmed that E. pellita influences nursery phenotypes, while E. grandis excels in early field growth, with ABLUP and ssGBLUP models showing slightly improved accuracy. These findings underscore the operational value of integrating genomic and nursery phenotypic data for efficient screening and selection in Eucalyptus hybrid breeding, providing a cost-effective strategy for improving plantation productivity in tropical environments.

Early selection of superior genotypes is critical in Eucalyptus hybrid breeding programs to accelerate genetic gain and enhance resource efficiency. This study investigates the genetic relationship between nursery phenotypes and early field growth performance in a hybrid clonal population of E. pellita × E. grandis. A total of 623 hybrid clones were assessed for seven nursery traits: seedling height, collar diameter, leaf number, branch number, main root number, root quadrant, and root dry weight. Following on, field performance was evaluated at 12 months for height, diameter at breast height, and volume. Genetic parameters were estimated using Best Linear Unbiased Prediction (BLUP), Pedigree-based BLUP (ABLUP), and Single-step Genomic BLUP (ssGBLUP), with Principal Component Analysis (PCA) used to reduce phenotypic dimensionality. Multivariate mixed models and Spearman rank correlations were applied to explore trait relationships across pedigree hierarchies and species contributions. Results demonstrated strong correlations between root and shoot traits, with PCA identifying key axes related to seedling vigor, root architecture, and canopy structure. Incorporating genomic data into ssGBLUP models improved genetic parameter estimation, highlighting the impact of non-additive genetic variance. Multivariate analysis revealed strong correlations within nursery traits and moderate correlations between nursery and early field traits. Spearman rank analysis showed that root-related traits, particularly in E. grandis, were strongly linked to field performance, while E. pellita exhibited trade-offs between certain traits and field growth. Gradient boosting machine analysis confirmed that E. pellita influences nursery phenotypes, while E. grandis excels in early field growth, with ABLUP and ssGBLUP models showing slightly improved accuracy. These findings underscore the operational value of integrating genomic and nursery phenotypic data for efficient screening and selection in Eucalyptus hybrid breeding, providing a cost-effective strategy for improving plantation productivity in tropical environments.

Kata Kunci : Eucalyptus pellita × E. grandis hybrids, Nursery traits, Genetic correlations, ssGBLUP vs ABLUP, Early field growth performance