Effects of Amino Acids and Salicylic Acid on Biochemical Responses and Genetic Stability of Tissue-Cultured Date Palm Offshoots Under Salt Stress

Abstract

The present study was conducted at the Department of Horticulture and Landscape, College of Agriculture, University of Basrah, on three-year-old tissue culture-derived date palm offshoots (Phoenix dactylifera L., cv. Barhee). It aimed to evaluate the effects of amino acid and salicylic acid foliar application on alleviating salinity stress during the 2025–2026 growing season. Plants were irrigated with saline water at 10 dS m⁻¹ (100 mM), and treated with amino acid mixture (0, 100, 200 mg L⁻¹) and salicylic acid (0, 100, 200 mg L⁻¹). Results showed that the combined application of 200 mg L⁻¹ amino acids and 200 mg L⁻¹ salicylic acid significantly improved biochemical traits. This treatment produced the highest total chlorophyll content (5.318 mg g⁻¹) and soluble protein content (5.446 mg g−1), while reducing proline to 3.766 mg g⁻¹ and lipid peroxidation to 2.043 mg g⁻¹, and enhancing membrane stability index to 71%. SDS-PAGE analysis revealed 43 protein bands, indicating changes in protein expression under salinity and treatments. Cluster analysis grouped treatments into two main clusters; notably, the combination of 100 mg L⁻¹ salicylic acid and 200 mg L⁻¹ amino acids formed a distinct group with a genetic stability index of 0.8%. Overall, salinity induced noticeable biochemical and genetic alterations, whereas amino acids and salicylic acid effectively mitigated stress effects and improved plant performance and genetic stability.