Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and water, plant hormonal functions, and vital metabolic pathways. Few studies are available on the application of combined nanomaterials to mitigate salinity stress on potato plants (Solanum tuberosum L. cv. Diamont). In order to assess the effects of the sole or combined application of silicon (Si) and potassium (K) nanoparticles and biochar (Bc) on the agro-physiological properties and biochemical constituents of potato plants grown in saline soil, two open-field experiments were executed on a randomized complete block design (RCBD), with five replicates. The results show that the biochar application and nanoelements (n-K and n-Si) significantly improved the plant heights, the fresh and dry plant biomasses, the numbers of stems/plant, the leaf relative water content, the leaf chlorophyll content, the photosynthetic rate (Pn), the leaf stomatal conductance (Gc), and the tuber yields, compared to the untreated potato plants (CT). Moreover, the nanoelements and biochar improved the content of the endogenous elements of the plant tissues (N, P, K, Mg, Fe, Mn, and B), the leaf proline, and the leaf gibberellic acid (GA3), in addition to reducing the leaf abscisic acid content (ABA), the activity of catalase (CAT), and the peroxidase (POD) and polyphenol oxidase (PPO) in the leaves of salt-stressed potato plants. The combined treatment achieved maximum plant growth parameters, physiological parameters, and nutrient concentrations, and minimum transpiration rates (Tr), leaf abscisic acid content (ABA), and activities of the leaf antioxidant enzymes (CAT, POD, and PPO). Furthermore, the combined treatment also showed the highest tuber yield and tuber quality, including the contents of carbohydrates, proteins, and the endogenous nutrients of the tuber tissues (N, P, and K), and the lowest starch content. Moreover, Pearson’s correlation showed that the plant growth and the tuber yields of potato plants significantly and positively correlated with the photosynthesis rate, the internal CO₂ concentration, the relative water content, the proline, the chlorophyll content, and the GA3, and that they were negatively correlated with the leaf Na content, PPO, CAT, ABA, MDA, and Tr. It might be concluded that nanoelement (n-K and n-Si) and biochar applications are a promising method to enhance the plant growth and crop productivity of potato plants grown under salinity conditions.

Drought stress in arid regions is a serious factor affecting yield quantity and quality of economic crops. Under drought conditions, the application of nano-elements and nano-agents of water retention improved the water use efficiency, growth performance, and yield quantity of drought-stressed plants. For this objective, two field experiments were performed and organized as randomized complete block designs with six replications. The treatments included kaolin (5 t. ha⁻¹) bentonite (12.5 t. ha⁻¹), perlite (1.25 t.ha⁻¹), N-zeolite (1.3 L.ha⁻¹), N-silicon (2.5 L.ha⁻¹), and N-zinc (2.5 L.ha⁻¹). The current study showed that the application of silicon, zinc, and zeolite nanoparticles only positively influenced the morphological, physiological, and biochemical properties of the drought-stressed coriander plant. Exogenous application of N-silicon, N-zinc, and N-zeolite recorded the higher growth parameters of drought-stressed plants; namely, plant fresh weight, plant dry weight, leaf area, and root length than all the other treatments in both seasons. The improvement ratio, on average for both seasons, reached 17.93, 17.93, and 18.85% for plant fresh weight, 73.46, 73.46, and 75.81% for plant dry weight, 3.65, 3.65, and 3.87% for leaf area, and 17.46, 17.46, and 17.16% for root length of drought-stressed plants treated with N-silicon, N-zinc, and N-zeolite, respectively. For physiological responses, the application of N-zeolite, N-silicon, and N-zinc significantly increased leaf chlorophyll content, photosynthetic rate, water use efficiency, chlorophyll fluorescence, and photosystem II efficiency compared with the control in both seasons, respectively. Similar results were observed in antioxidant compounds, nutrient accumulation, and phytohormones. In contrast, those treatments markedly reduced the value of transpiration rate, nonphotochemical quenching, MDA, ABA, and CAT compared to control plants. Regarding the seed and oil yield, higher seed and oil yields were recorded in drought-stressed plants treated with N-zeolite followed by N-silicon and N-zinc than all the other treatments. Application of N-zeolite, N-silicon and N-zinc could be a promising approach to improve plant growth and productivity as well as to alleviate the adverse impacts of drought stress on coriander plants in arid and semi-arid areas.