Impact of Titanium Dioxide Nanoparticles in Irrigation Water on Potato Growth and Yield

A 2-year (2017 and 2018) field lysimeter study was carried out to examine the effect of titanium dioxide nanoparticles (TiO₂ NPs) in irrigation wastewater on soil characteristics and potato (Solanum tuberosum L.) yield. Potatoes were planted in lysimeters (1.00 m × 0.45 m) in sandy soil and subjected to four treatments: freshwater (FW), wastewater (WW), freshwater + TiO₂ NPs (FW + NP) and wastewater + TiO₂ NPs (WW + NP), in triplicate. Potato tubers were harvested at maturity (120 days after planting). Both the TiO₂ NPs (with/without 1 mg L⁻¹ TiO₂ NPs) and irrigation treatments (FW vs. WW) had a significant effect (p ≤ 0.05) on chlorophyll content; however, they had little or no effect on soil physicochemical parameters (cation exchange capacity (CEC), pH and soil organic matter (SOM)), plant growth parameters (plant height, above-ground and root fresh weight) or yield (tuber weight, number of tubers and tuber grading). For both years, the total nitrogen content of the leaves increased consistently together with leaf chlorophyll content. Furthermore, tuber yield under FW, WW and WW + NP treatments were higher in the first year than in the second, likely due to higher growing season temperatures in the second year. This study furthers the knowledge on the impact of TiO₂ NPs on plant growth by showing that at 1 mg L⁻¹, irrigation water can increase greenness without inhibiting plant growth and yield. In addition, the potato plants, irrigated with water containing TiO₂ NPs, did not become infected with early and late blight diseases either year.