Black locust (Robinia pseudoacacia) is recognised as a forest species of interest due to its multiple uses. The management of forest genetic resources and their efficient conservation suffer from variations in traits and start with seed germination. The aim of the current study was to investigate the germination of seeds obtained from plus trees selected in eight Romanian provenances, as well as to investigate the influence of the origin upon plants’ growth and development. Two experiments were undertaken to test seed germination: one treatment involved water-soaked seeds and heat/cold treatment, while the other treatment was based on sulphuric acid, at different concentrations (50, 70, 90%). The results were correlated with the morphological analysis of the seeds. Satu-Mare had the lowest germination rate within both treatments. Sulphuric acid did not improve seed germination as much as the heat treatment. The highest germination rate occurred for the water and temperature treatment on seeds from Bihor provenance (68.2%). The most distant provenance was Bihor, in inverse correlation with Bistrița Năsăud and grouped separately within the hierarchical dendrogram of cluster analysis based on the analysed parameters of the provenances investigated. The results demonstrated that the genotypes and environmental heterogeneity of the seed origin within the provenances may finally result in different performances.

The influence of the geographical origin of eight Romanian provenances of Robinia pseudoacacia on the characteristics of seeds, germination, and growth of seedlings in young stages of life was analyzed. Four experiments were undertaken to test seed germination (thermal treatment at distinct temperatures, mechanical scarification, acetone 90%, and biostimulator). The germination percentage showed that scarification treatment provided the best results among all treatments (41.7%). Seeds soaked in water at 100 °C provided the second-highest germination rate. Furthermore, the same two treatments also assured the highest values for the seedlings’ length. There were registered significant differences among the provenances for the analyzed characteristics, the seed germination capacity, and the growth rate of the seedlings in the first years of life. The study highlighted the resources that could ensure good quality of the reproductive forest material, which can be used in new afforestation and breeding programs. Pearson correlations and multivariate analysis provided interesting and useful information about R. pseudoacacia provenances and 13 characteristics of the seeds and seedlings, highlighting the relationship among them. The results could be of interest for the efficient use of forest genetic resources and the obtention of quality reproductive material in black locust.

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.