Ikhlasse Bentaleb

Optimizing growing conditions is essential for the conservation and promotion of medicinal plant species such as Caralluma tuberculata, a succulent plant of great medicinal importance. This project, this particular research was done at the experimental station of the Faculty of Sciences in Oujda, aims to evaluate the impact of two types of substrates, peat and sand, on the morpho-physiological parameters and anthocyanin pigment accumulation in Caralluma tuberculata. The study compared the effect of these substrates on germination rate and kinetics, as well as aerial and root development and red pigment concentration in transplanted seedlings. The results show that the final germination rate is not significantly different between the two substrates (p=0.358), although peat promotes faster kinetics. On the other hand, peat proved to be significantly superior for growth, resulting in significantly greater stem height (8.49 cm) and root length (8.26 cm). Conversely, sand caused an extremely significant accumulation of anthocyanin pigments, reaching 100.00%, compared to 16.20% for peat. This accumulation is interpreted as a physiological defense response to the more pronounced environmental stress in the sandy substrate. These results suggest that the choice of substrate should be based on the cultivation objective. For biomass production, peat and sand should be used to induce protective secondary metabolites.

This study investigates the effect of salt and water stress on the germination performance of Origanum majorana seeds. Salinity was applied using 0, 50, 100, and 150 mM NaCl, while water stress was simulated, using PEG 6000, at values of 0, -0.1, -0.7, and -1 MPa. In all treatments, germination percentage and rate of germination were measured. Results showed that germination decreased with increasing salt and water stress. However, at 50 mM NaCl (moderate salinity) or -0.1 MPa (moderate water stress), germination remained high (about 82-85%) and comparable to the control. High salinity (>100 mM NaCl) or intense water stress (-0.7 MPa and above) reduced germination to below 40-45%. Germination curves exhibited a typical sigmoid shape due to their longer lag times and lower germination rates under salt and water conditions. The results obtained suggest that Origanum majorana shows moderate tolerance to salinity and is highly sensitive to intense environmental stress. Hence, the current experiment indicates that Origanum majorana is moderately tolerant to salt stress and highly sensitive to stronger stress conditions, confirming that appropriate management is needed if this plant is cultivated in arid and semi-arid conditions.