Abstract
<title>Abstract</title> <p>Seed germination is often challenged by several environmental constraints, such as salinity stress, which affect germination performance and plant establishment. In the case of argan seeds, optimizing the germination process is considered pivotal for a successful establishment. Therefore, this study evaluated the potential of a microalgae extract to enhance argan seed germination performance and alleviate salt-induced germination inhibition. The results demonstrated that under non-saline and saline conditions, the optimal dose of 1 g/L effectively enhanced germination performance and mitigated stress by doubling the germination rate (+ 50% to 130%), while stimulating radicle elongation (+ 69 to 105%), and increasing the seedling vigor index (2-fold to 4-fold). Biochemically, microalgae application maximized osmotic adjustment and macromolecular protection by boosting soluble sugar and total protein content, while strongly stimulating the synthesis of polyphenols and flavonoids. At the same time, the application of the biostimulant alleviated the seed’s physiological distress, whereas untreated seeds showcased major oxidative crisis marked by the accumulation of proline and hyperactivation of antioxidant enzymes (superoxide dismutase, peroxidase, polyphenol oxidase), whilst the application of the microalgae reduced antioxidant enzyme activity and osmoprotectant content. In conclusion, the microalgae extract application induced effective protective priming, constituting a promising agroecological strategy for supporting argan seed germination in arid saline areas.</p>