Abstract <p>Rice (<i>Oryza sativa</i> L.), a staple crop widely cultivated in salinity-prone regions of Iran, experiences significant yield losses due to sodium toxicity and oxidative stress. This study investigated the physiological and biochemical mechanisms by which root drench application of salicylic acid alleviates salt stress in rice seedlings. A randomized complete block design with three replicates was used, including multiple salinity levels and salicylic acid treatments. Salicylic acid application improved salinity tolerance by enhancing ion homeostasis, osmotic adjustment, and antioxidant defense systems. Treated plants showed reduced sodium accumulation, improved potassium balance, and better root growth under saline conditions. In addition, salicylic acid promoted proline accumulation and strengthened antioxidant enzyme activities, leading to reduced oxidative damage. Overall, the results indicate that root-applied salicylic acid enhances plant tolerance to salinity through coordinated regulation of ionic balance, osmotic adjustment, and redox homeostasis. These findings highlight its potential as an effective strategy for improving rice performance under salt stress.</p>