In Vitro Propagation and Conservation of Lavandula stoechas subsp. luisieri and Pterospartum tridentatum, Two Important Medicinal and Aromatic Species from Portugal

Abstract

Lavandula stoechas subsp. luisieri and Pterospartum tridentatum are two valuable aromatic and medicinal plants. Their biometric and morphological parameters, such as the number of new shoots, length of the longest shoot, multiplication rate, and fresh weight, were evaluated using the multiplication MS medium protocol. The rooting protocols involved immersing the explants in IBA (1 g L−1) and a commercial IBA (3.3 g L−1) preparation (Clonex®). Slow-growth conservation assays were carried out using two different sucrose concentrations (15 g L−1 and 30 g L−1), and a control, with the cultures kept at 4 °C for 12 months. The multiplication rate for L. stoechas subsp. luisieri was 6.8, and that of P. tridentatum was 13.3, achieved using the MS medium supplemented with 0.2 mg L−1 BAP, 1 mg L−1 BAP, and 0.5 mg L−1 IBA. The application of Clonex® showed the best ex vitro rooting results in L. stoechas subsp. luisieri (77%) and P. tridentatum (90%). In the slow-growth conservation assays, at 4 °C, in darkness for 12 months, an excellent survival rate was achieved in L. stoechas subsp. luisieri (>80%) and P. tridentatum (>90%), even at the reduced sucrose concentration. This study demonstrates the effectiveness of in vitro multiplication and ex vitro rooting protocols for two valuable aromatic and medicinal plants. These findings are significant for the ex situ conservation of these species, as they provide effective long-term preservation and utilization strategies.