Evaluation of the synergistic efficiency of hormonal, biological and physical stimuli in the induction and growth of callus in lavender

<ns3:p> Background Lavender is a crucial source of secondary metabolites with medicinal and industrial importance. Its exploitation faces challenges due to the limited availability of raw materials and their sensitivity to climate. Tissue culture techniques, particularly callus culture, represent the most sustainable method for the continuous production of these active compounds. Methods This study focused on developing an effective protocol for inducing and stimulating callus cultures in lavender plants. In the growth phase, different concentrations of 2,4-D and benzyladenine were assessed. In the induction phase, different concentrations of the growth regulator 2, 4-D (0, 1, 2 and 3) mg L <ns3:sup>−1</ns3:sup> were tested under light and dark conditions. The experimental approach investigated three primary variables hormone concentration, environmental conditions and the type of nutrient medium. A comparative analysis was also completed between two nutrient media, MS and B5, supplemented with different Chitosan concentrations (0, 50, 100 and 200) mg. L <ns3:sup>−1</ns3:sup> . Results The results indicated that the optimal concentration for callus induction was 1 mg L <ns3:sup>−1</ns3:sup> of 2,4-D, with the highest callus formation rate 95% recorded under dark conditions. Among all treatments, the combination of 2, 4-D 1 mg L <ns3:sup>−1</ns3:sup> and BA 2 mg L <ns3:sup>−1</ns3:sup> was the most effective for sustainable callus growth. Regarding the nutrient medium, B5 was more efficient than the MS medium. For the biostimulants, Chitosan at 100 mg L <ns3:sup>−1</ns3:sup> recorded the highest efficiency in both fresh and dry callus weights. Conclusions This study underscores the necessity of integrating hormonal, nutritional and environmental factors for optimal callus production. </ns3:p>