Abstract
Cistus crispus (Cistaceae) is a species adapted to arid and semi-arid conditions, and it has ornamental and medicinal uses. In Italy, native populations of C. crispus are threatened by the collection due to the low number of individuals in the populations, anthropogenic pressure, and the changing environmental condition that enhance other more aggressive and hybridisable Cistus species. Here, we set up the variables for its micropropagation protocols to achieve a high number of plants per unit time. Various steps of the micropropagation protocol were modulated, including various sodium hypochlorite concentrations (CHCs) and time of sterilisation. The efficiency of the protocol maximised at 25 min sterilisation with 2.5% CHC and decreasing explant vitality at increasing time and CHC. Both shoot proliferation and root emissions were maximised at 1.78 μM N-6-benzyladenine (BA) in the growing medium, with up to 5.4 explants per cycle, with 5.8 roots per explant, and 84 healthy explants. Kinetin stimulated further the axillary root proliferation more than dimethylallylamino purine or BA. Lastly, the application of indole acetic acid increased root emissions during the acclimation stage more than the application of indole butyric acid, and this occurred irrespective of their concentrations, up to 2.0 μg · g−1. These results can foster the use of C. crispus as an ornamental species, for xeriscaping or for the extraction of its secondary compounds, which have various industrial uses. These results can also have an indirect implication for the conservation of the species by reducing the collection for ornamental purposes from its natural population.