Growth and resistance to mechanical stress in the young phase of black locust (Robinia pseudoacacia L.) trees based on geographical provenances

The black locust (Robinia pseudoacacia L.) is valued for its rapid growth, adaptability, and high-quality wood. This study analyzed seedlings from eight Romanian provenances to assess their growth potential, physiological traits, and mechanical resistance. Over the first six years, tree height and trunk diameter exhibited significant variations among provenances, with some genotypes demonstrating a higher capacity for biomass accumulation based on growth-related traits. Differences in leaf morphology, chlorophyll content, and wood strength indicate that genetic variation, environmental adaptation, and genotype-by-environment interactions shape these traits. Ecological factors at seed sources, such as temperature and precipitation, further influenced the trees' resilience to local stressors. Multivariate analysis identified strong correlations among vegetative growth traits and between foliage characteristics and provenance-specific climatic conditions, suggesting inherited clinal trends shaped by environmental stressors. Broad-sense heritability estimates (0.318-0.794) highlight the potential for genetic improvement through selective breeding. At least three genotypes exhibited favorable traits, including enhanced wood resistance to compression and bending stress, making them suitable for afforestation, ornamental landscaping, and ecological rehabilitation of degraded lands. The selection of resilient genotypes could improve the sustainable use of land vulnerable to abiotic stressors and extreme climatic events. Future research should investigate the long-term stability of early growth patterns, explore genotype-environment interactions, and assess hybrid breeding strategies to enhance tree growth and resilience in diverse ecological conditions.