Rapid In Vitro Propagation of Quercus gilva via Nodal Explants: A Protocol for Culture Establishment, Shoot Proliferation, and Ex Vitro Rooting

Quercus gilva is a dominant species in the subtropical evergreen broad-leaved forests of East Asia with substantial economic and ecological value. However, efficient clonal propagation methods for this species remain limited. This study aimed to establish a micropropagation protocol for Q. gilva using nodal stem segments from two-year-old seedlings as explants, focusing on culture establishment, shoot induction, shoot proliferation, and ex vitro rooting. Aseptic culture was effectively established by rinsing explants under running water for 15 min, followed by immersion in 0.1% HgCl2 for 8 min, which balanced contamination control and explant viability. Explant browning was reduced by pre-soaking in 1.0 g·L−1 ascorbic acid (VC) and by supplementing the Murashige and Skoog (MS) medium with 3.0 g·L−1 activated charcoal. The highest shoot induction percentage (80.0%) was obtained on MS medium containing 1.0 mg·L−1 2,4-D and 0.5 mg·L−1 TDZ. Shoot proliferation was achieved by subculturing induced shoots on MS medium supplemented with 1.0 mg·L−1 NAA and 1.0 mg·L−1 2iP. For ex vitro rooting, regenerated shoots were dipped in a solution containing 600.0 mg·L−1 IBA plus 700.0 mg·L−1 NAA and then transplanted into a substrate of peat and perlite (1:1, v/v), resulting in a rooting percentage of 70.0% and well-developed root systems. This study establishes a preliminary in vitro propagation framework for Q. gilva, providing a methodological reference for future studies aimed at improving clonal propagation efficiency.