Mitigating Combined Boron and Salt Stress in Lettuce (Lactuca Sativa L. Semental) through Salicylic Acid-Modified Rice Husk Biochar

Purpose: This study thoroughly investigates innovative amendment salicylic acid (SA) modified rice husk biochar (SABC) designed to improve boron (B) and salinity tolerance in lettuce, providing a comprehensive exploration of their potential effects in alleviating stress-induced challenges. Methods: Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy were used for the molecular and chemical characterization of the biochar samples. The treatments consisted of control, 40 mM NaCl plus 20 mg B kg^-1 (NaCl + B), and 40 mM NaCl plus 20 mg B kg^-1 and 5 g kg^-1 SA-modified rice husk biochar (NaCl + B + SABC). Results: Under conditions of salt and B toxicity, SABC treatment significantly prevented the decrease in plant weight induced by stress. SABC reduced the concentrations of B, sodium (Na), and chloride (Cl) in plants, while increasing the concentrations of potassium (K) and silicon (Si). The hydrogen peroxide concentration, which increased as a result of B and salt toxicity, was decreased with SABC. The activities of the antioxidant enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APX) showed a significant increase under stress, but due to the positive effect of SABC in reducing B and salt stress, there was a decrease in the activities of these enzymes. Conclusions: The results obtained from this study indicate that SABC is effective in reducing boron and salt stress. Testing the SABC molecule in different plants and under various stress conditions could provide significant contributions to the stress literature.