Phosphogypsum and biosynthesized selenium nanoparticles synergistically mitigate cadmium contamination and promote maize growth in wastewater-irrigated alkaline soil

Abstract

Aims: Maize (Zea mays L.), a critical crop for global food security, is indispensable for livestock feed and human consumption. However, the prolonged use of cadmium-contaminated wastewater for irrigation, particularly in alkaline soil, can cause soil degradation and poses a significant threat to crop production. Methods: The study tested the combined application of 10 t ha^-1 PG and 25 mg L^-1 BioSeNPs on maize plants cultivated in Cd-contaminated alkaline soils. Comprehensive assessments were conducted on soil chemical properties, enzymatic activities, plant physiological responses, and nutrient content in leaves. Results: The co-application of PG and BioSeNPs significantly reduced Cd bioavailability in the soil and its accumulation in maize roots, shoots, and grains. Soil Cd levels decreased by 33.01%, accompanied by enhanced soil enzymatic activities and improved soil respiration. Physiological stress markers, including malondialdehyde (MDA) and hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>), were reduced by 34.61%. Additionally, chlorophyll content, stomatal conductance, and net photosynthetic rate increased by 54.23%, 54.28%, and 93.80%, respectively. The nutritional content of essential elements—nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and selenium (Se)—in maize leaves also showed substantial improvements. Conclusions: The combined application of PG and BioSeNPs effectively mitigated Cd contamination and enhanced soil health and maize growth. This innovative approach offers a sustainable solution for managing alkaline soils irrigated with Cd-contaminated wastewater.