Optimization of auxin treatments and rooting media for the propagation of common lilac (Syringa vulgaris L.)

Common lilac (Syringa vulgaris L.) is an important landscape shrub used for both functional and aesthetic purposes in garden design. Therefore, it is important that it can be easily propagated. This study investigated the effects of various growing/rooting media and auxins on the rooting of lilac semi-hardwood cuttings. Perlite, peat, and equal mixtures of both were used as rooting media. The 1000 and 2000 ppm doses of both auxins indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) were applied to lilac cuttings. The callus formation and rooting rates, number of roots, root length, and fresh root weight were recorded. The highest callusing rate was observed with 2000 ppm IBA in a perlite medium (28.00%). The same medium and treatment yielded the highest rooting rate (27%). The longest root length (12.66 cm) was obtained from the perlite medium with 1000 ppm NAA. The highest number of roots (15.66 pieces) was observed from peat medium with 2000 ppm IBA and 1000 ppm NAA. The highest fresh root weight (3.63 g) was obtained from the perlite-peat mix with 1000 ppm IBA. In conclusion, the rooting success of lilac cuttings varied significantly depending on the growing medium and the hormone type/concentration combination.