Foliar Application of Lobularia maritima‑derived Polysaccharides Modulates Chemical Composition and Enhances Salt Tolerance in Greenhouse‑Cultivated Durum Wheat

Biostimulant use in the agrochemical industry has increased in recent years because of their ability to improve nutrient use efficiency, stimulate growth, and protect against stress. This study investigated the effect of exogenous application of the halophyte Lobularia maritima natural polysaccharide (PSLm) on the salinity tolerance of durum wheat plants grown in a greenhouse environment. A foliar spray of 2 mg mL− 1 PSLm or purified water was administered weekly to seedlings regardless of their exposure to 150 mM NaCl until the end of their life cycle. Phenotypic, physiological, and biochemical traits were monitored, along with gene expression and chemical composition analyses. The results showed that salinity reduced the growth of durum wheat seedlings, whereas PSLm stimulated their growth and improved their yield regardless of salt exposure. The foliar application of PSLm positively affected the fully expanded leaves of durum wheat seedlings, which was accompanied by a delay in plant senescence; a decrease in lipid peroxidation and reactive oxygen species; an increase in plant biomass, total leaf area, relative water content, membrane stability index, leaf chlorophyll fluorescence, total soluble sugar and proline contents, and improved antioxidant activities and relative expression levels of ten stress-related genes. This study suggested that foliar spraying with PSLm can overcome the negative effects of NaCl stress on durum wheat by regulating physiological and biochemical processes, achieving approximately 91% of the yield of untreated plants. In the future, this approach could serve as the basis for the development of an effective and sustainable method for improving salt tolerance