Influence of Root Formation Stimulants on Lemon-Scented Thyme (Thymus Citriodorus (Pers.) Schreb.) Propagation by Semi-Lignified Cuttings

The aim of the study is to evaluate the efficacy of root formation stimulants to enhance vegetative propagation of lemon thyme (Thymus citriodorus (Pers.) Schreb.) under controlled environmental conditions. The study was conducted from October to November 2025 at the N.V. Tsitsin Main Botanical Garden of the Russian Academy of Sciences to assess the effect of root formation stimulants (Kornevin and Epin) on rooting and cutting development of several varieties of lemon thyme (Thymus citriodorus (Pers.) Schreb.): Lemon Variegata, Mystic Lemon, and Goldy. The experiment was performed under controlled conditions: temperature (22 ± 2) °C, air humidity (75 ± 3) %, photoperiod of 14 hours, illumination of 7000 lux. The experiment involved semi-lignified cuttings (8 ± 1) cm long, 30 for each of three treatments (control, Kornevin, and Epin). Treatment with Kornevin resulted in the highest rooting rate – 86 % while in the control group, this figure was 51 %. Treatment with Epin increased rooting to 76 % but also limited root and shoot growth. The greatest number of roots formed with Kornevin treatment, while cuttings treated with Epin demonstrated the shortest root system length and volume, as well as reduced shoot growth. A two-way analysis of variance confirmed the significant effects of the preparations on key parameters of cutting rooting. The data obtained indicate that Kornevin is the most effective agent for vegetative propagation of thyme using semi-woody cuttings, while Epin can be used given its dual action – stimulating root formation and inhibiting further growth of rooted cuttings.