The yield and quality of field crops are affected by abiotic stresses such as water deficit, which can negatively impact crop growth, productivity, and quality. However, nanotechnology holds great promise for increasing crop yield, maintaining quality, and thus mitigating abiotic stresses. Therefore, the current study was conducted to examine the influences of 0, 50, and 100 mg L⁻¹ zinc oxide (ZnO) nanoparticles and 0, 25, and 50 mg L⁻¹ silicon dioxide (SiO₂) nanoparticles on the yield and quality traits of potato plants grown under water deficit conditions (100%, 75%, and 50% ETc). Water deficit significantly reduced yield traits (average tuber weight, number of plant tubers, and tuber yield) and quality traits (tuber diameter, crude protein, and mineral content). However, it enhanced tuber dry weight, specific gravity, ascorbic acid, starch, and total soluble solids. Foliar applications of ZnO and SiO₂ nanoparticles under water deficit treatments significantly enhanced yield and improved quality traits of potato plants. Moreover, significant and positive correlations were found among yield traits. Thus, it can be concluded that using ZnO NPs at 100 mg L⁻¹ significantly improves potato productivity and quality traits by mitigating the negative effects of water deficit in arid regions.

Water deficit is a major challenge for sustainable global food security, especially, in arid and semi-arid regions. Nanotechnology is regarded as an effective tool for managing a wide range of environmental stresses by providing novel and practical solutions. A field experiment was conducted to assess the effects of zinc oxide nanoparticles ‘ZnO NPs’ (0, 50, 100 ppm) and silicon dioxide nanoparticles ‘SiO₂ NPs’ (0, 25, 50 ppm) as an exogenous application on the physiological indices, total yield and water use efficiency (WUE) of potato under water deficit conditions (50%, 75%, and 100% of crop evapotranspiration (ETc) water requirements). Water deficit significantly decreased most physiological indices and yield traits of potato, but increased proline content and WUE. In contrast, exogenous application of ZnO NPs and SiO₂ NPs to plants grown under different water deficit treatments resulted in an increase in leaf gas exchange, leaves relative water contents (LRWC), photosynthetic pigments, and leaf green index. Under different water deficit treatments, the highest total yield and harvest index traits were obtained from plants treated with ZnO-NPs-100 ppm followed by 50 ppm of ZnO and SiO₂ NPs, respectively. The highest WUE was recorded when the potato plants were irrigated with 50% ETc and exogenous treated with 100 ppm of ZnO NPs compared with fully irrigated plants. In conclusion, the exogenous application of ZnO NPs (100 ppm) can significantly mitigate the water deficit stress and improve the physiological, yield, and WUE of potato grown in arid regions under water deficit conditions.

A field study was conducted to understand the effectiveness of foliar applications of ZnO-NPs (0, 50, 100 mg L⁻¹) and SiO₂-NPs (0, 25, 50 mg L⁻¹) on potato plant growth, morphology, nutrient uptake, oxidative stress, and antioxidative response under drought conditions (i.e., 100% crop evapotranspiration ETc, 75% ETc, and 50% ETc). Results revealed that water deficiency significantly hampered plant growth and biomass production and stimulated oxidative stress in potatoes. However, the exogenous application of ZnO-NPs and SiO₂-NPs significantly improved plant growth attributes such as the number of branches, plant height, fresh and dry biomass, leaf area, and leaf area index as compared with untreated plants. The foliar application of ZnO-NPs (i.e., 100 and 50 mg L⁻¹) and SiO₂-NPs (50 mg L⁻¹) promoted the mineral ion accumulation in plants grown under water deficiency and thus resulted in higher NPK, Zn²⁺, Fe²⁺, and Mn²⁺ contents. A significant reduction in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) was found in plants treated with 100 mg L⁻¹ ZnO followed by 50 mg L⁻¹ SiO₂ and 50 mg L⁻¹ ZnO nanoparticles as compared with untreated plants, respectively. Furthermore, the aforesaid treatments resulted in the maximum activity of antioxidant enzymes (i.e., superoxide dismutase SOD, catalase CAT, polyphenol oxidase PPO, and ascorbate peroxidase APX) under water deficit stress. Similarly, the foliar application of ZnO and SiO₂ nanoparticles improved nonenzymatic antioxidants such as total flavonoid content (TFC) and total phenolic compounds (TPC) as compared with untreated plants (control). Moreover, plant growth traits were significantly and positively correlated with mineral contents, while they were negatively correlated with MDA and H₂O₂. ZnO-NPs and SiO₂-NPs applications improved biochemical traits, which might lead to enhancements in plant tolerance and improvements in potato growth, productivity, and quality traits under water shortage conditions.

The possibility of inducing systemic resistance in roselle against root rot and wilt diseases was investigated using biotic and abiotic inducers. The biotic inducers included three biocontrol agents (i.e., Bacillus subtilis, Gliocladium catenulatum, and Trichoderma asperellum) and two biofertilizers (i.e., microbein and mycorrhizeen), while the abiotic inducers included three chemical materials (i.e., ascorbic acid, potassium silicate, and salicylic acid). In addition, preliminary in vitro studies were conducted to evaluate the inhibitory activity of the tested inducers on the growth of pathogenic fungi. The results show that G. catenulatum was the most efficient biocontrol agent. It reduced the linear growth of Fusarium solani, F. oxysporum, and Macrophomina phaseolina by 76.1, 73.4, and 73.2%, respectively, followed by B. subtilis by 71.4, 69, and 68.3%, respectively. Similarly, potassium silicate was the most effective chemical inducer followed by salicylic acid, each at 2000 ppm. They reduced the linear growth of F. solani by 62.3 and 55.7%; M. phaseolina by 60.7 and 53.1%; and F. oxysporum by 60.3 and 53%, respectively. In the greenhouse, all inducers applied as a seed treatment and/or foliar spray strongly limited the development of root rot and wilt diseases. In this regard, G. catenulatum, at 1 × 10⁹ CFU mL⁻¹, achieved the highest values of disease control, followed by B. subtilis; while T. asperellum, at 1 × 10⁵ CFU mL⁻¹, recorded the lowest values. In addition, the plants treated with potassium silicate followed by salicylic acid, each at 4 g/L, recorded the highest disease control compared to ascorbic acid at 1 g/L, which had the lowest values. The mixture of mycorrhizeen + microbein (at 10 g/kg seeds) was the most effective compared to either of them alone. All treatments, applied alone or in combination in the field, significantly reduced the incidence of diseases. The most effective treatments were a mixture of G. catenulatum (Gc) + Bacillus subtilis (Bs) + Trichoderma asperellum (Ta); a mixture of ascorbic acid (AA) + potassium silicate (PS) + and salicylic (SA); G. catenulatum; potassium silicate; and a mixture of mycorrhizeen + microbein. Rhizolix T had the highest disease-reducing efficacy. In response to the treatments, significant improvements in growth and yield, changes in biochemicals, and increased activities of defense enzymes were achieved. This research points to the activity of some biotic and abiotic inducers that can play a vital role in managing the root rot and wilt of roselle through the induction of systemic plant resistance.