An Argan (Argania spinosa L.)- Derived Biochar Enhances Date Palm (Phoenix dactylifera L.) Growth Under Salt Stress

A pot study was conducted to evaluate the impact of applying an argan-derived biochar on the reaction of date palm seedlings of Mejhoul and Boufeggous cultivars to salt stress. The experiment followed a completely randomized design with two levels of biochar amendment (B: control, 0% biochar; B + : 5% biochar) and one level of sodium chloride (NaCl) at 154 mM. The responses of both cultivars were evaluated after two months through the assessment of plant shoot elongation, leaf area, chlorophyll content index measurements, and the accumulation of proline, malondialdehyde (MDA), catalase activity, and other salt stress-related parameters. The results indicated significant improvements in plant growth, as evidenced by a threefold increase in shoot elongation rate upon the application of biochar. Furthermore, there was a twofold enhancement in relative leaf water content (RWC) and a fivefold elevation in chlorophyll content index (CCI). Moreover, when subjected to salt stress, the levels of MDA and hydrogen peroxide (H 2 O 2 ) increased, but experienced a twofold decrease in the leaves of both cultivars’ seedlings when biochar was introduced to the substrate. This enhanced salinity tolerance was linked to notable increases in the antioxidant activity of both catalase (CAT) and peroxidase (POX) activities (fivefold and twofold, respectively), as well as total phenolic compounds, relative water content (RWC %), chlorophyll content, and a threefold reduction in the Na + /K + ratio. Therefore, it can be concluded that this argan derived biochar could be used to reduce the negative impacts of salinity stress in date palm ( Phoenix dactylifera L.) which suggests that the utilization of this biochar could offer a practical solution for addressing saline phoeniculture. Furthermore, these findings contribute to the existing knowledge by providing evidence of the beneficial effects of argan-derived biochar in enhancing salinity tolerance in date palm seedlings. Graphical Abstract