Preparation of Granular Organic Iodine and Selenium Complex Fertilizer Based on Biochar for Biofortification of Parsley.

This study investigates the potential of biochar derived from various biomass sources: apricot kernel (AK), pine sawdust (PS), rice husk (RH), wheat straw (WS), and reed stem (RS) to enhance the yield, nutritional quality, and environmental sustainability of parsley crops. Comprehensive characterization through SEM, EDAX, nitrogen adsorption-desorption isotherms, and FTIR analyses identified AK biochar as the most suitable for further enrichment due to its superior specific surface area (512.3 m²/g) and iodine number (51.23 mg/g). EDAX analysis revealed that AK biochar exhibited the highest carbon content (92.1%), while RH biochar contained the highest silicon content (46%), indicating different potential applications. FTIR analysis identified key functional groups, such as carbonyl (1740 cm⁻¹) and hydroxyl (3430 cm⁻¹) groups, which contribute to the biochar's reactivity and potential effectiveness in various applications. The effects of selenium (Na₂SeO₄), iodine (KI), their combination (Na₂SeO₄ + KI), and BISF (biochar-enriched iodine and selenium fertilizer) on parsley growth, antioxidant properties, and nutrient accumulation were evaluated. The results demonstrated that joint applications of iodide and selenate led to a 3.1-fold increase in iodine content (up to 16.8 mg/kg d.w.) and a 1.2-fold increase in selenium accumulation (up to 2482.1 μg/kg d.w.) in parsley compared to separate treatments. Additionally, BISF treatment significantly improved key biometric parameters, with leaf weight increasing by 1.6 times (up to 326.5 g) compared to the control, and antioxidant content-ascorbic acid, polyphenols, and antioxidant activity-showing increases of 1.56, 1.27, and 1.50 times, respectively. This study underscores the effectiveness of selenium- and iodine-enriched biochar in enhancing parsley crop yield and nutritional quality while also demonstrating the multifunctional role of biochar in environmental remediation.