Zinc Oxide Nanoparticles (ZnO NPs), Biosynthesis, Characterization and Evaluation of Their Impact to Improve Shoot Growth and to Reduce Salt Toxicity on Salvia officinalis In Vitro Cultivated

Abstract

Green synthesis of zinc oxide nanoparticles (ZnO NPs) using plant extracts have recently attracted considerable attention due to their environmental protection benefits and their easy and low cost of fabrication. In the current study, ZnO NPS were synthesized using the aqueous extract of Ochradenus arabicus as a capping and reducing agent. The obtained ZnO NPs were firstly characterized using ultraviolet visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), energy dispersive X-ray absorption (EDX), zeta potential, and zeta size. All these techniques confirmed the characteristic features of the biogenic synthesized ZnO NPs. Then, ZnO NPs were evaluated for their effects on morphological, biochemical, and physiological parameters of Salvia officinalis cultured in Murashige and Skoog medium containing 0, 75, 100, and 150 mM of NaCl. The results showed that ZnO NPs at a dose of 10 mg/L significantly increased the shoot number, shoot fresh weight, and shoot dry weight of Salvia officinalis subjected or not to the salt stress. For the shoot length, a slight increase of 4.3% was recorded in the plant treated by 150 mM NaCl+10 mg/L ZnO NPs compared to the plant treated only with 150 mM of NaCl. On the other hand, without NaCl, the application of both concentrations 10 mg/L and 30 mg/L of ZnO NPs significantly improved the total chlorophyll content by 30.3% and 21.8%, respectively. Under 150 mM of NaCl, the addition of 10 mg/L of ZnO NPs enhanced the total chlorophyll by 1.5 times, whilst a slight decrease of total chlorophyll was recorded in the plants treated by 150 mM NaCl + 30 mg/L ZnO NPs. Additionally, ZnO NPs significantly enhance the proline accumulation and the antioxidative enzyme activities of catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR) in plants under salinity. Our findings revealed that green synthesized ZnO NPs, especially at a dose of 10 mg/L, play a crucial role in growth enhancement and salt stress mitigation. Hence, this biosynthesized ZnO NPs at a concentration of 10 mg/L can be considered as effective nanofertilizers for the plants grown in salty areas.

Recent advances in nano-fertilizers: synthesis, crop yield impact, and economic analysis

“…Saffan et al 223 Report that combined bio-nano fertilizers (Cu and Se) improve tomato production under saline irrigation. According to Alenezi et al, 224 ZnO nanoparticles synthesized in an environmentally friendly manner from Ochradenus arabicus extract have a practical nanofertilizer effect of stimulating growth and reducing salt stress in Salvia officinalis. Fig.…”

Biochar nanoparticles alleviate salt stress in tomato (Solanum lycopersicum) seedlings

“…Similarly, under 150 mM NaCl treatment, the root zone addition of 10 mg kg −1 ZnO NPs enhanced the total chlorophyll by 1.5 times in Salvia officinalis , and this value reached the same level as the untreated controls at day 56. 57 In another study involving Vigna radiata seedling exposure to 200 mM NaCl, the total chlorophyll content was increased by 15.7% after the application of 250 μM Zn salt. 58 High concentrations of salts in the soil will lead to increased osmotic stress, confounding water uptake and causing leaf water imbalance.…”

Improving the Production of Secondary Metabolites via the Application of Biogenic Zinc Oxide Nanoparticles in the Calli of Delonix elata: A Potential Medicinal Plant

“…Water-soluble metabolites, such as alkaloids, phenolic compounds, and terpenoids, and coenzymes are the major reducing agents involved in the nanoparticle’s green synthesis [ 63 ]. The extracts of several plant species were successfully employed in producing nanoparticles [ 64 , 65 , 66 , 67 ]. Nanoparticles, in turn, have been used as elicitors to improve the plant’s bioactive compounds, as these compounds are commercially valued to be widely used in the medical, pharmacological, cosmetic, agriculture, and food industries [ 68 ].…”