Effects of phosphorus fertilizer on kenaf growth physiology and copper absorption in copper-contaminated soil

Abstract

Copper (Cu) contamination in agricultural soils is one of the health risks, due to its translocation to humans through the food chain. Therefore, optimized nutrient application is required to achieve higher yields with reduced Cu uptake, ensuring food security. One way to reduce soil contamination is phytoremediation. Phosphorus (P) application decreases oxidative stress, improves plant growth, and facilitates the phytoremediation potential of plants. This study investigated the phytoremediation potential of kenaf (Hibiscus cannabinus) with P fertilizer in Cu-polluted mining soil (2375 mg kg^− 1 Cu) of Hubei, China. A pot experiment was conducted to assess the effect of P on kenaf growth, gas exchange traits, antioxidant enzyme activities, Cu uptake, and soil health under different levels of P (0, 10, 15, and 20 g/15 kg of soil). P₁₅ significantly improved plant growth by increasing plant height, stem diameter, number of leaves, and SPAD (relative chlorophyll index). Application of P improved net photosynthesis (Pn), transpiration rate (Tr), stomatal conductance (gs), and intercellular CO₂ concentration (Ci) while decreasing oxidative stress in kenaf leaves up to P₁₅. Contradictory, a high concentration of P₂₀ was toxic to the morphological and physiological traits of the plants. Maximum Cu uptake was observed at P₂₀ in roots, leaves, stems, and fibers. Additionally, P application significantly decreased soil pH and bulk density. Our findings revealed the effectiveness of P application in improving kenaf growth in heavily Cu-polluted mining soil.