Molybdenum Trioxide Nanoparticles Enhance Drought Tolerance in Pea Plants

Legumes family plants, high in protein and essential minerals for humans and animals, play a vital role in the food industry. However, they are susceptible to a warming climate and especially droughts. The pea plant is a legume that carries out nitrogen fixation from the air to the soil with the help of symbiotic bacteria on the root nodules. A sufficient amount of molybdenum in the soil is significant for nitrogen fixation. The aim of this research was to investigate the effects of an aqueous suspension of molybdenum trioxide nanoparticles (MoO₃ NPs) on the antioxidant system, mineral composition, and yield of drought-affected peas (Pisum sativum L. cultivar 'Respect'). The experiments were conducted using potted plants in a greenhouse with natural daylight. Pea plants were treated with different concentrations (0, 12.5, 25, and 50 ppm) of MoO₃ NPs by watering and spraying and were subjected to ten days of drought. Drought was initiated by maintaining substrate moisture at 30% while standard conditions were 80%. The researchers evaluated the impact of MoO₃ NPs and drought on the growth of the plants, the activity of enzymes (CAT, SOD, APX, GR, GPX), and the level of non-enzymatic antioxidants (FRAP, DPPH, ABTS, TPC) and stress biomarkers (H₂O₂, MDA amount). Elemental analysis was performed using the leaves, stems, and roots. The findings indicated that 50 ppm MoO₃ NPs significantly increased the yield, height, leaf area, and nodule number of drought-stressed pea plants. MoO₃ nanoparticles increased the activity of CAT, APX, SOD, and GPX. The highest Mo accumulation was found in pea roots when the plants were watered with NPs suspensions. MoO₃ nanoparticles increased the resistance of pea plants to drought stress by boosting the antioxidant activity, which may have led to higher growth parameters and yield of pea plants.