Abstract
Currently, there is an increasing interest in nanotechnology, since some nanomaterials can enhance crop growth, yield, nutritional status, and antioxidant defences. This work aimed to investigate for the first time the influence of zinc oxide nanoparticles (ZnO-NPs) on the in vitro growth and biochemical parameters of the olive tree (cv. Moraiolo). With this goal, biogenic ZnO-NPs (spherical shape and dimensions in the range of 10–20 nm), deriving from a green synthesis carried out with a Lemna minor L. extract were used. Different concentrations (0, 2, 6 and 18 mg L−1) of ZnO-NPs were added to the olive growth medium (OM substrate), and three sub-cultures of 45 days each were carried out. ZnO-NPs at 6 and 18 mg L−1 enhanced some growth parameters in the olive tree explants, such as the number of shoots, green fresh and total dry weight. Moreover, the abovementioned concentrations raised the chlorophyll a and b content and soluble protein. Finally, concerning the dosage applied, the treatments stimulated the content of carotenoids, anthocyanins, total phenol content (TPC), and the radical scavenging activity towards DPPH (2.2-diphenyl-1-picrylhydrazyl). In conclusion, this study highlighted that biogenic ZnO-NPs exerted beneficial effects on the olive tree explants in vitro, improving the effectiveness of the micropropagation technique.
Highlights
Zinc (Zn) is an essential micronutrient involved in many biological processes which take place in plants, being a cofactor of numerous enzymes such as RNA polymerase, superoxide dismutase, alcohol dehydrogenase, and carbonic anhydrase
The zinc oxide nanoparticles (ZnO-NPs) at the dosages of 6 and 18 mg L−1 positively influThe ZnO-NPs treatment increased the number of shoots produced at the dosages of enced the green fresh weight, which was higher than the control
L−1 positively alsoinfluenced found for the total dry weight
Summary
Zinc (Zn) is an essential micronutrient involved in many biological processes which take place in plants, being a cofactor of numerous enzymes such as RNA polymerase, superoxide dismutase, alcohol dehydrogenase, and carbonic anhydrase. For this reason, Zn is essential for protein, carbohydrates and lipids synthesis and nucleic acids and antioxidant metabolism [1]. Some of the symptoms related to Zn excess are reductions of plant biomass, chlorosis of young leaves, and the inhibition of root growth [5] For these reasons, Zn is considered an essential nutrient for plant growth and development, even if it could be toxic in excessive amounts
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