Developing an improved protocol for micropropagation of sycamore maple (Acer pseudoplatanus L.)

Abstract Sycamore maple ( Acer pseudoplatanus L.) is an ecologically and economically important hardwood in Central Europe. For high-value genotypes, like wavy grain maple, in vitro propagation offers a promising tool for targeted multiplication and conservation. This study contributed to an optimised micropropagation protocol by testing disinfection protocols, silver nitrate supplementation, cytokinin type, and light conditions. Winter buds from 36 donor trees were disinfected with either sodium hypochlorite (NaOCl) or sodium dichloroisocyanurate (NaDCC). NaDCC markedly reduced contamination (5.2% vs. 42.2% for NaOCl in crown buds) and simplified handling, recommending it for routine application. Across genotypes, 11.8 µM silver nitrate significantly enhanced multiplication (up to 3.4-fold), elongation and shoot quality, particularly in difficult-to-propagate genotypes. Trans-zeatin riboside showed minor, genotype-specific advantages over trans-zeatin, whereas sterilisation method (filter-sterilisation vs. autoclaving) had no effect. Light intensity was the main driver of multiplication and biomass accumulation, with optimal results at 50–60 µmol m⁻² s⁻¹. Red-enriched spectra (RB ratios of 3:1 or 1:1) further promoted multiplication and elongation, but higher irradiance reduced SPAD values and induced anthocyanin pigmentation, suggesting potential light-induced stress. The combination of NaDCC disinfection, silver nitrate supplementation, trans-zeatin riboside, and tailored light regimes provided a reproducible framework for efficient sycamore maple micropropagation. These findings support genotype-specific protocol adjustments to balance morphological gains with physiological quality, enabling effective clonal production of elite timber genotypes.