Cadmium (Cd) stress has negative impacts on potato growth and development. It decreases key functional processes such as nutrient uptake, cell expansion, while increasing enzyme activity that ultimately results in the overall reduction in crop yield. However, the effects of the combined application of vermicompost (VC) and zinc oxide (ZnO) nanoparticles (NPs) on potato growth, productivity, quality, and soil health under Cd stress are still unknown. In the present study, the foliar application of ZnO-NPs (0, 10, 20 mg L−1); VC addition (without VC and with VC 10% w/w); and Cd spiking (without Cd and with Cd stress (30 mg kg−1 of soil)) on potato productivity was examined. The results revealed that Cd stress decreased the growth, biomass, and photosynthetic function in potato plants. However, the application of ZnO-NPs and VC treatments increased the Zn contents by limiting the uptake of Cd in potato plants. Under Cd stress, there was a decrease in leaf dry weight (73.22%), stem diameter (39.10%), and total chlorophyll contents (41.48%), while an increase in electrolyte leakage (85.55%), H2O2 contents (38.37%), and O2-contents (145.03%) was noticed compared to control (no Cd stress). Growth and biomass in the plants treated with VC and ZnO-NPs showed significant improvements compared to the control group. Both VC and ZnO-NPs applications, taken individually or in combination, were effective in reducing proline accumulation (12.89%) and malondialdehyde generation (5.25%) relative to control, while improving the accumulation of the osmolytes. The combined approach showed better tuber and soil enzymatic activities compared to control. Moreover, the additive action of all VC and ZnO-NPs decreased the tuber Cd accumulation and increased the Zn contents in the potato tubers. Using both VC and ZnO-NPs together mitigated the negative effects caused by Cd stress by lowering Cd accumulation and enhancing growth, biomass, activity of antioxidant enzymes, and osmoprotectant levels. These sustainable techniques are beneficial for reducing Cd stress, protecting soil health, and improving tuber nutrition with Zn.
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