Exogenous Applications of Bio-fabricated Silver Nanoparticles to Improve Biochemical, Antioxidant, Fatty Acid and Secondary Metabolite Contents of Sunflower

Abstract

The present study involved the bio-fabrication of silver nanoparticles (AgNPs) by using the Euphorbia helioscopia L. leaves aqueous extract to improve the production of secondary metabolites in industrially important sunflower (Helianthus annuus L.) plants. Phyto-fabrication of AgNPs was confirmed by using spectrophotometry, SEM imaging and X-ray diffraction analysis. The morphological and optical characterization manifested that the AgNPs are crystalline and exist in the size range of 30–100 nm. Various concentrations (10, 20, 40, 60, 80 and 100 mg/L) of AgNPs were applied in combinations on sunflower seeds and crop plants. The effects of biosynthesized AgNPs were evaluated for agro-morphological parameters (plant height, flowering initiation and seed weight), biochemical metabolites (chlorophyll, proline, soluble sugar, amino acid and protein contents) and enzymatic activities (superoxide dismutase and ascorbate peroxidase) in sunflower and 60 mg/L concentration of AgNPs on sunflower seeds and foliar sprays on plants in combination were found to be effective to elicit biochemical modifications to improve secondary metabolites. It was also observed experimentally that 60 mg/L concentration of AgNPs improved the biochemical, fatty acid and enzymatic attributes of sunflower plants, which in turn improved the plant agro-morphological parameters. Near-infrared spectroscopic analysis results confirmed the improvement in the seed quality, oil contents and fatty acid composition (palmitic acid, oleic acid and linoleic acid) after the applications of AgNPs. The findings of the present investigation confirm the exogenous applications of bio-fabricated AgNPs in combinations on seeds and plants to improve the plant yield, seed quality and secondary metabolite contents of the sunflower plants.

Evaluating Impacts of Biosynthetic Silver Nanoparticles on Morphophysiological Responses in Barley (Hordeum vulgare L.)

“…The findings of the current study demonstrated that the use of AgNPs increased the proline level in leaves and roots of barley plants compared to control. Similar results were also reported concerning the increase in the levels of proline content due to the application of AgNPs [30,79,80]. This increase is likely a protective response to shield the plants from heightened oxidative stress caused by elevated concentrations of AgNPs [81].…”

“…The concentration and size of the AgNPs are limiting factors in the effect that occurs in the plant, in addition to dosage, duration of exposure, and type of plant species. There are many studies indicating that appropriate concentrations of AgNPs play an important role in boosting growth, photosynthetic efficiency, and notable secondary metabolite production [30][31][32]. For instance, recent studies showed a positive response to plant growth indices after exposure to optimal levels of AgNPs.…”

Advancing sustainable agriculture: a critical review of smart and eco-friendly nanomaterial applications

“…During foliar application, stomatal permeation, epidermal absorption and internalization are the major ways to make foliage to absorb these nanoparticles. This has many advantages that include helping to fight plant diseases and pathogens, providing essential micronutrients through leaves that are rarely present in nutrition-deficient soil [ 31 – 34 ]. Unlike seed priming and foliar application, a soil mixture of NPs, hydroponic culture or in vitro application paves the way for the NPs to directly meet the ecosystem; and may cause negative impacts to soil ecosystem.…”

Nanobionics in Crop Production: An Emerging Approach to Modulate Plant Functionalities

“…For example, Ag NPs in the concentration ranging from 40–60 mg L −1 have successfully been studied for improving the chlorophyll content in the Trigonella foenum-graecum L. (effective dose of 40 mg L −1 ) [ 47 ], Cucumis sativus (50 mg L −1 ) [ 48 ], Eschscholzia californica Cham (25 mg L −1 ) [ 49 ], and Helianthus annuus L. (60 mg L −1 ). A higher dose (100 mg L −1 ) caused sharp decline (by 48.3%) in the concentration of chlorophyll [ 50 ]. Ag NPs are also reported to enhance the coefficient of photochemical quenching, thereby implying an inhibition of the electron transport chain [ 51 ].…”