Biofortification of tomato fruits with cobalt and its impact on bioactive compounds content

Biofortification is a viable strategy for improving the nutritional value of crops. For this reason, the use of nanoparticles (NPs) in tomato plants has emerged. This study aimed to evaluate the impact of foliar application of cobalt oxide NPs (CoO NPs) on the mineral and bioactive compound content of tomato fruits. Three concentrations of CoO NPs (250, 500, and 1000 mg L-1), one concentration of cobalt sulfate (CoSO4, 500 mg L⁻1), and a control group were used as treatments. The results demonstrate that the form of cobalt (Co) application directly impacts its accumulation, with the ionic form (CoSO4) being more efficient than CoO NPs for biofortifying tomato fruits. Furthermore, we observed that CoO NPs increased the phosphorus (P) and magnesium (Mg) content but decreased sulfur (S). Regarding the content of bioactive compounds, we observed an increasing trend in vitamin C, lycopene, phenols, and flavonoids with the application of CoO NPs, especially compared to CoSO₄. In conclusion, the form of cobalt applied has different effects, cobalt sulfate (CoSO4) is more efficient for biofortification, while cobalt oxide nanoparticles (CoO NPs) are more efficient in increasing the content of bioactive compounds in tomato fruits.