Morphological, Biochemical and Nutritional Responses of Potato (Solanum tuberosum L. cv. Agria) to SiO2 Nanoparticles under Alkalinity Stress Conditions

Considering the destructive effects of alkalinity stress on plants and the important role of silicon in stress alleviation, this study investigated the effects of foliar-applied silicon dioxide nanoparticles (SiO₂-NPs) at 0, 2, and 4 mM, under alkalinity stress induced by NaHCO₃ at 0, 5, 15, and 30 mM, on hydroponically grown potato ( Solanum tuberosum L. cv. Agria). Under non-stress conditions, SiO₂-NPs, particularly at 4 mM (N4), significantly enhanced plant growth, increasing plant length (8.5%), dry weight (15.3%) and root biomass (up to 38.6%) compared to the control (N0). Alkalinity stress alone exhibited a dose-dependent detrimental effect, severely suppressing growth parameters by up to 65% at 30 mM NaHCO₃. Importantly, SiO₂ nanoparticles significantly interacted with stress and provided a strong protective effect. This protective role extended to mini-tuber yield, where N4 maintained higher productivity under moderate and severe stress. Biochemically, SiO₂-NPs enhanced the antioxidant defense system, elevating carotenoids, total phenolics and flavonoids. Nanoparticles also preserved chlorophyll content and significantly reduced the depletion of mineral ions under stress conditions. The 4 mM SiO₂-NP treatment reduced the severe loss of key nutrients and retained magnesium (21.0%), iron (31.6%), potassium (33.2%) and calcium (42.6%) compared to the untreated control under high alkalinity conditions. The results demonstrate that foliar application of SiO₂-NPs, especially at 4 mM, increases alkalinity tolerance in potato plants by improving growth, antioxidant activity and nutrient uptake. Also, 5 mM NaHCO₃ acted as a beneficial root carbon source and showed a slight increase in some parameters compared to non-stress conditions. These results provide a suitable strategy for sustainable seed potato production in soilless systems with alkaline water.