Auxin, substrate and light interaction enhances rooting efficiency in Taxus baccata cuttings

Taxus baccata L., an endangered woody species with poor rooting ability in stem cuttings, faces propagation challenges that limit its conservation and sustainable utilization. This study aimed to enhance rooting efficiency by investigating the combined effects of auxin type and concentration, substrate composition, and blue light exposure. A factorial experiment based on a completely randomized design with three replications was conducted, testing two auxins (NAA and IBA at 15 and 25 mg/L), two substrates (75% perlite + 25% peat moss and 100% perlite), and three blue light durations (2, 4, and 6 h/day). All main factors and their interactions markedly affected rooting percentage, callus formation, root biomass, survival, and rooting time. The treatment combining 25 mg/L NAA, 75% perlite + 25% peat moss, and 4 h/day of blue light produced the most favorable results, achieving the highest rooting and callus formation with the shortest rooting period. Blue light improved rooting performance by promoting auxin activity and stimulating physiological processes related to cell division and adventitious root initiation. Rooting time showed a negative relationship with callus formation, survival rate, and root biomass. These findings provide a mechanistic insight into auxin–substrate–light interactions and offer a practical protocol for efficient vegetative propagation and conservation of Taxus baccata L.