Impact of Silver Nanoparticles on Lemon Growth Performance: Insecticidal and Antifungal Activities of Essential Oils From Peels and Leaves

Abstract

Ten-year-old lemon (Citrus limon L. cv. Eureka) was used during the 2019 and 2020 seasons to investigate the effect of AgNPs at control, 5, 7.5, and 10 mg/L as a foliar application on vegetative growth, yield, and fruit quality. The selected trees were subjected to agricultural practices applied in the field during the study. The results indicated that the foliar application of AgNPs positively improved the shoot length, total chlorophyll, flower, and fruit set percentage, fruit yield, physical and chemical characteristics of fruits, and leaf mineral composition from macro and micronutrients compared to control in both seasons. The foliar application of AgNPs at 10 mg/L showed the highest mean values followed by 7.5 and 5 mg/L, respectively, for the previous characteristics. The treated leaves and fruit peels were hydrodistillated to extract the essential oils (EOs), and GC–MS analysis of leaf EOs. The analysis of leaves EOs showed the presence of neral, geranial, neryl acetate, and limonene as the main abundant bioactive compounds. While in peel the main compounds were neral, geranial, neryl acetate, D-limonene, geraniol acetate, linalool, and citronellal. Toxin effect of both EOs from leaves and peels were evaluated on the rice weevils (Sitophilus oryzae) and the results indicated a higher effect of lemon peel EOs than leaves based on mortality percentage and the values of LC50 and LC95 mg/L. Melia azedarach wood samples loaded with the produced lemon EOs were evaluated for their antifungal activity against the molecularly identified fungus, Fusarium solani (acc # OL410542). The reduction in mycelial growth was increased gradually with the applied treatments. The most potent activity was found in lemon leaf EOs, while peel EOs showed the lowest reduction values. The mycelial growth reduction percentages reached 72.96 and 52.59%, by 0.1% leaf and peel EOs, respectively, compared with control.

Biosynthesized silver nanoparticles mediated by Ammi visnaga extract enhanced systemic resistance and triggered multiple defense-related genes, including SbWRKY transcription factors, against tobacco mosaic virus infection

“…Under greenhouse conditions, the foliar applications of Ag-NPs increased chlorophyll content. Several studies found that using Ag-NPs improved the shoot and root systems, the length and width of leaves, the amount of chlorophyll, carbohydrates, proteins, and antioxidant enzymes in bean, wheat, Brassica juncea and lemon [50][51][52]. Moreover, the accumulation of TMV-CP gene reduced in all Ag-NPs treatments and different concentrations compared with TMV infected plants.…”

Insecticide Efficacy of Green Synthesis Silver Nanoparticles on Diaphorina citri Kuwayama (Hemiptera: Liviidae)

“…Although silver is not an essential element for citrus development, it can cause beneficial effects, such as promotion in vegetative bud development, an increase in total chlorophyll, tolerance to biotic stress, as well as an increase in fruit set percentage [54,55]. Some studies suggest that both the promoter and the phytotoxic effects that AgNPs can generate are related to the Ag ion content and not to the size of the nanoparticles [56]; for example, AgNPs synthesized from extracts of Moringa oleifera Lam.…”

Metabolomics as a Tool to Understand Nano-Plant Interactions: The Case Study of Metal-Based Nanoparticles

“…On the other hand, the levels of amino acids (valine, serine, and aspartate) and the shikimate-phenylpropanoid biosynthesis were down-regulated, while some metabolites of the aspartate pathway increased, suggesting up-regulation of the aspartate family to feed the TCA cycle for energy supply [ 69 ]. Recently, it was found that foliar application of nAg (5, 7.5, and 10 mg L −1 ) can alter the essential oil composition of leaves and peels of lemon trees [ 127 ].…”