Smart foliar fertilizer based on Zn-Alg-CaCO₃ microparticles improves Aquaponic tomato cultivation

The increasing global demand for sustainable food production, coupled with the micronutrient limitations of aquaponic systems, calls for innovative fertilization strategies that enhance crop yield and nutritional quality while preserving environmental integrity. This study evaluates the effectiveness of zinc-functionalized calcium carbonate microparticles (Zn-Alg-CaCO₃ MPs) as a smart foliar fertilizer in aquaponics. Tomato plants (Solanum lycopersicum L. cv. Principe Borghese) were grown in a recirculating aquaponic system and treated with three concentrations of Zn-MPs (10, 50, and 250 ppm) via foliar spray, using a control group treated with water. Each treatment was applied to 15 plants under controlled greenhouse conditions. Yield parameters, antioxidant content, and nutritional quality were assessed. The 250 ppm treatment significantly increased yield per plant (+ 74.9%), number of fruits (+ 44.4%), and average fruit weight (+ 22.1%) compared to control. Antioxidant activity, phenolic, flavonoid, and lycopene content were also enhanced, particularly at the highest dose. Importantly, no increase in zinc was detected in recirculating water, highlighting the environmental safety of foliar application. These findings underscore the potential of Zn-Alg-CaCO₃ MPs as a sustainable solution for precision fertilization in aquaponic agriculture. Further molecular and environmental studies are recommended to optimize and scale this technology.