Carbon-Free Fungicide for Sustainable Agriculture: An Efficient Niobium Compound against Foliar Fungi

Among the daunting challenges to the sustainability of the agricultural sector is the development of environmentally sound technologies driving food security and higher yields together with an integrated “One Health” approach. This work explores a new niobium molecule, PNB53, as a potent antifungal agent with potential benefits for agricultural productivity and low environmental impact. In vitro tests were performed to evaluate the efficiency of PNB53 in controlling target and nontarget fungi by the production of reactive oxygen species. Greenhouse and field experiments on soybean crops were conducted to check for antifungal activity and effects on productivity, in comparison with commercial fungicides. The results showed that PNB53 presented a significant decrease in the damage caused by Asian soybean rust (Phakopsora pachyrhizi) in soybean crop, with 61% efficacy, and performed better against Corynespora cassiicola (42.4%) than the commercial fungicides (39.4%). The biological control nontarget fungus Trichoderma harzianum was not affected by doses higher than the field dose in vitro. The productivities in the field were 4531, 4465, and 3446 kg ha–1, respectively, for PNB53, the commercial fungicide, and the untreated check. Thus, 140 g ha–1 of PNB53 promoted a yield increase of 18.1 bags per hectare over the control plots, indicating a positive physiological effect on crops. In view of the growing demand for food supplies commensurate with population growth, niobium-based compounds can offer a great contribution to food security and become a potential alternative for sustainable agriculture.