Variations in the biochemical characteristics of Lavandula sublepidota Rech.f. in response to the foliar enrichment of green-synthesized copper nano complexes from extract of neem and jujube

Abstract

Copper (Cu) is an essential micronutrient in plant physiology and biochemistry. This article synthesized copper nano complexes (Cu–NCs) based on aqueous extracts of jujube and neem leaves. The effects of foliar application of Cu-jujube and Cu-neem Cu–NCs at concentrations of 0, 10, 25, and 50 mg L−1 on the bioactive compounds, antioxidant capacity, and essential oil of the Iranian native medicinal herb Lavandula sublepidota Rech. f. was investigated. The highest levels of flavonoids and polyphenols were observed in the plants treated with Cu–NCs at 25 mg L−1. However, no superiority was observed between the two types of Cu–NCs. Furthermore, 25 mg L−1 nCu-Z and nCu-N foliar application boosted essential oil yield (48 and 52%, respectively) over control. This suggests an ideal threshold beyond which toxicity was found. Similarly, the amount of commercially significant secondary metabolites increased at 25 mg L−1 CuNCs compared to 10 and 50 mg L−1 concentrations. The maximum antioxidant activity was found in extracts of lavender that had been treated with 25 mg L−1 CuNCs. When CuNCs were applied exogenously, the extracts' antibacterial activity (MIC μg mL−1) was substantially increased against the three pathogen strains. The results suggest that CuNCs demonstrate notably greater effectiveness, particularly at an ideal concentration of 25 mg L−1, in enhancing the production of essential oil and bioactive compounds in Lavandula sublepidota Rech. f. Therefore, these findings indicate the importance of the biosynthesis of NCs using plants and measuring the phytochemical changes of lavender plants.