The impact of MoO₃ nanoparticles on peas' macro- and micro-elemental composition

Molybdenum (Mo) is an essential micronutrient and required for nitrogen metabolism and plant enzyme activity. Nanoparticles (NPs) have become an important research topic due to their ability to increase plants' nutritional efficiency and promote growth. Molybdenum trioxide NPs (MoO₃) may be a promising tool to improve the availability of Mo to plants. However, their effects on plants' micro- and macronutrient composition have not been sufficiently studied. The aim of this study was to evaluate the influence of MoO₃ NPs on micro- and macronutrient changes in pea plants (Pisum sativum). The research was carried out in a greenhouse, in which seven green pea (Respect’) seedlings were grown in 10 L vegetative pots. When the peas reached the 39 BBCH growth stage, they were foliar sprayed to full wetness (ca. 14±0.5 mL plant⁻¹) or watered (100±1 mL per pot) with suspensions containing different concentrations of MoO₃ NPs: 0 (watered or sprayed with distilled water), 0.0125, 0.025, and 0.05 mg mL^-1. At the end of the experiment, peas were harvested to assess the interactive effects of MoO₃ NPs on their elemental composition. The results showed that exposure to MoO₃ NPs through the roots led to an increase in Mo content of up to 43%, while foliar treatment resulted in an increase of up to 47% in pea leaves. In pea stems, the Mo content increased by up to 34% when the plants were treated through the roots, and it rose even higher, by up to 46%, when the pea plants were treated through the leaves. When watering peas with MoO₃ NPs, the accumulation of Mo in the roots was 2 to 3.6 times greater, and after foliar application, the accumulation was 1.3 to 1.8 times higher compared with untreated plants. MoO₃ NPs strongly reduced the accumulation of Ca, Mg, Na, and Fe in pea leaves and stems. The study results reveal the potential of MoO₃ nanoparticles in sustainable crop production but emphasize the need for precise regulation of their use.