The effect of a modified DKW nutrient medium and antioxidant-adsorbent synergy on the in vitro regeneration of Liriodendron tulipifera L.
Abstract
The study aimed to improve the in vitro regenerative response of Liriodendron tulipifera L. by optimizing the mineral composition of the DKW nutrient medium and reducing phenolic oxidation, a major limitation in woody plant micropropagation. Agrochemical analysis of donor plant soils revealed deficiencies in phosphorus, zinc, and boron, which were corrected through targeted fertilization to enhance explant physiological quality. A modified DKW medium enriched with KH₂PO₄ (+30 mg L⁻¹), FeNaEDTA (+10.37 mg L⁻¹), and increased Mn and Zn concentrations significantly improved morphogenic performance compared with the standard DKW control. Among the hormonal treatments, the combination BAP 1.5 mg L⁻¹ + kinetin 0.5 mg L⁻¹ + GA₃ 0.2 mg L⁻¹ (RA variant) yielded the highest number of lateral buds, apical leaves, and lateral leaves after 21 days. Subsequent optimization with antioxidant–adsorbent combinations demonstrated that higher concentrations of ascorbic acid (150–250 mg L⁻¹) together with activated charcoal (0.5–1 g L⁻¹) markedly reduced phenolic oxidation and tissue necrosis. The V6 treatment (250 mg L⁻¹ ascorbic acid + 1 g L⁻¹ activated charcoal) achieved the highest explant viability (92%) and leaf formation. These results confirm that mineral-adjusted DKW medium combined with antioxidant–adsorbent synergy provides an effective protocol for the microclonal propagation of L. tulipifera, offering a reliable strategy for the regeneration of phenolic, woody species.