Green Synthesis of Biogenic Nano-Silicon From Rice Husk and Its Effect on Combined Boron and Salinity Stress Tolerance of Barley and Wheat

This study aimed to assess the potential benefits of externally applied biogenic Nano-Si in combating combined salinity and B toxicity in barley and wheat plants. Nano-Si was prepared from rice husk, and its functional and structural properties were determined using XRD and SEM. Synthetic saline and B-toxic soil was created by adding 60 mM NaCl + 10 mM NaHCO3 and 5 mg kg-1 B to normal field soil. Nano-Si was applied to the soil at rates of 0, 25, 50, and 100 mg kg-1. The application of Nano-Si demonstrated a significant positive effect on plant weight. Barley and wheat plants exhibited a significant increase in proline and total chlorophyll content with the application of 50 and 100 mg kg-1 Si levels. In wheat, electrolyte leakage decreased significantly with the 50 and 100 mg kg-1 Si treatments. Increasing levels of applied Si significantly increased the Si concentration in plants. Silicon treatments significantly reduced the K concentrations only at low Si dose in barley. However, the K concentration in wheat plants enhanced with the increased Si doses. Sodium and chloride concentrations in both plants decreased significantly with increasing Si treatments as compared to control. Silicon treatments at the rate of 50 and 100 mg kg-1 resulted in a significant reduction in wheat's B concentrations. Interestingly, in contrast, Si applications have led to an increase in barley's B concentrations as compared to control. Biogenic Nano-Si shows great potential as an ecological source of Si and yielded promising results in preventing salt and B toxicity in wheat but not barley.