Biochemical responses of olive Olea europaea L. seedlings treated with salicylic and ascorbic acids under salt stress

• Noor Hamid Jaafar Al-Waeli, Hadeer Abd-Alkadhim Hamza AL-Alwani, Sarab Kareem Abbas and, Sura Jaafar mohammed.

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  The experiment was conducted in a greenhouse belonging at the Department of Horticulture and Landscape Gardening, College of Agriculture, Al-Qasim Green University, during the 2025–2026 growing season, Designed as a two-factor factorial experiment in a Randomized Complete Block Design (RCBD), the study aimed to evaluate the role of salicylic and ascorbic acid treatments in enhancing the biochemical efficiency of two-year-old olive seedlings. The first factor comprised three salinity levels ( 0 ,  100 , and  200  mmol L^-1   ), while the second factor included biostimulants, a control   0 , salicylic acid at  150   mg L^-1   , and ascorbic acid at  100  mg L^-1   .

the results showed that exposing the seedlings to salt stress, especially at the high concentration (200 mmol L^-1), caused a significant decrease in the biochemical characteristics of the olive seedlings, where chlorophyll, carbohydrates, and relative water content decreased, while in contrast, there was an increase in the leaf content of the amino acid proline and total phenols, and an increase in membrane permeability, foliar spraying with bio-stimulants led to physiological superiority, as the seedlings treated with salicylic and ascorbic acids overcame the negative effects of salinity, and the salicylic acid treatment achieved cellular membrane stability, increased leaf content of chlorophyll and carbohydrates, and increased relative water content, the maximum effectiveness of the dual interaction was demonstrated when exposing the seedlings to the highest salinity levels (200 mmol L^-1) with salicylic and ascorbic spraying, where the leaf content of proline increased, providing integrated osmotic and oxidative protection that enabled the seedlings to maintain balanced vegetative growth and a good photosynthetic system under severe stress conditions.

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