Effects of Copper and Silver Nanoparticle Seed Priming and Foliar Spray on Plant Growth and Thrips Infestation in Capsicum spp -

Effects of Copper and Silver Nanoparticle Seed Priming and Foliar Spray on Plant Growth and Thrips Infestation in Capsicum spp.

“Nanoparticle-Mediated Modulation of Plant Growth and Thrips Infestation in Capsicum spp." Capsicum annuum L., commonly known as pepper, is a vital vegetable with high nutritional value, known for its capsaicinoids and natural red colors. Nanoparticles (NPs) exhibit unique properties and have diverse applications, including in agriculture for disease reduction, plant protection, and as innovative diagnostic tools. This study explores the effects of seed priming and foliar spray with copper (Cu) and silver (Ag) nanoparticles on Capsicum spp. growth and resistance to thrips infestation. NPs, due to their small size and high surface area, have both stimulatory and inhibitory effects on plant growth, depending on concentration and plant type. Primed seeds and foliar-sprayed NPs have gained attention for promoting plant germination and enhancing stress resistance. Ag NPs, known for antibacterial and antifungal properties, are employed as plant growth promoters. Low concentrations of Ag NPs have been found to enhance crop stress resistance and increase plant cytokinin response. NPs also impact secondary metabolites in plants, triggered by abiotic and biotic stress. Thrips infestation can decrease the nutritional composition of plants, but NPs, particularly copper and silver, have been shown to modulate capsaicin and phytophenol concentrations in Capsicum species. This research investigates the effects of Ag, Cu, and Cu–Ag NPs on Capsicum, aiming to develop a reliable method for synthesizing NPs with potent repellent activity against thrips, ultimately enhancing plant growth and fruit metabolites. The study emphasizes the potential of foliar NPs application as an alternative approach to conventional soil-root treatments, offering promising economic and environmental benefits.

Material and Methods:

Plant Material: Three varieties of pungent chili seeds (Arka Sweta, Arka Meghana, and Arka Harita) were obtained from ICAR-Indian Institute of Horticultural Research. Seeds were washed, sterilized with sodium hypochlorite, and used for further experimentation.. Chemicals: Various chemicals, including silver nitrate, sodium borohydride, trisodium citrate, copper(II) sulfate pentahydrate, and others, were commercially purchased from Sigma-Aldrich.

 Synthesis and Characterization of NPs: Silver (Ag) and copper (Cu) nanoparticles were synthesized using specific chemical methods.

UV-visible spectrum, zeta potential, particle distribution, and Fourier transform infrared spectroscopy were employed for NP characterization.

Transmission electron microscopy (TEM) assessed the size and morphology of the NPs.

Storage Stability: The synthesized NPs were stored in a refrigerator, and their stability was evaluated after 40 days.

Effect of NP Priming on Chili Seedlings: Chili seeds were primed with Ag, Cu, and Cu-Ag NPs at different concentrations. Physiological parameters of seedlings were analyzed after 45 days.

Effect of Foliar Spray of NPs on Chili Plant: Chili seedlings were transplanted, and foliar sprays of Ag, Cu, and Cu-Ag NPs were applied at various concentrations. Growth characteristics, yield, and biochemical parameters were monitored.

Plant Material and Thrips: Thrips-infested chili plants were maintained under controlled greenhouse conditions. Various NP treatments were evaluated for their effectiveness against thrips infestation.

Effect of Foliar NPs on Biochemical Parameters of Chili:

Chlorophyll, carotenoids, total phenolic content (TPC), total flavonoid content (TFC), sugar reduction, and antioxidant activity were determined. High-performance liquid chromatography (HPLC) was used for capsaicinoids analysis.

Determination of Chlorophyll and Carotenoids: Leaf samples were extracted, and concentrations of chlorophyll and carotenoids were calculated.

Sample Extraction for Biochemical Assays: Extraction of leaf samples for TPC, TFC, sugar reduction, and antioxidant activity was performed.

 Antioxidant Activity: Total antioxidant activity, DPPH free radical scavenging activity, and ferric-reducing antioxidant power were assessed.

 Extraction and HPLC Analysis of Capsaicinoids:

Capsaicinoids extraction and quantification were carried out using HPLC. This methodology provides a comprehensive overview of the experimental procedures employed in the study, covering seed priming, foliar spray, thrips infestation, and biochemical analyses of chili plants treated with Ag, Cu, and Cu-Ag nanoparticles.

Research and Summary:

In this study, the potential of nanoparticles (NPs) to improve plant health and secondary metabolite production in Capsicum annuum (chili plants) was explored. Silver (Ag), copper (Cu), and copper-silver alloy (Cu-Ag) NPs were synthesized within the range of 25 to 86 nm, exhibiting zeta potentials between -28.8 to -38.5 mV. These NPs were applied through seed priming and foliar spray on three chili varieties—Arka Sweta (AS), Arka Meghana (AM), and Arka Harita (AH) grown in greenhouse conditions.

Seed Priming Effects:

Seed priming with various NP concentrations (1, 10, 20 ppm) significantly improved seed germination (96%), seedling vigor index (2494−3112.66), seedling length (6−49%), and biomass (46%) of 45-day-old Arka Meghana seedlings.

Elevated levels of chlorophyll (51−142%), carotenoids (23−94.2%), total phenolic content (73%), and total flavonoid content (57%) were observed in all plant tissues compared to the control.

Foliar Spray Impact:

Foliar spray of NPs (20−100 ppm) demonstrated a protective effect against thrips infestation (30−76%), indicating potential pest control benefits.

The foliar spray led to increased levels of chlorophyll (15−62%), carotenoids (15−50%), total phenolic content (20−62%), total flavonoid content (64−99%), reducing sugars (15−97%), total antioxidant activity (15−142%), ferric reducing antioxidant power assay (15−109%), DPPH (129−54 mg mL−1), and capsaicinoids (capsaicin and dihydrocapsaicin) (82−128%).

Size-Dependent Effects:

The study emphasized an inverse relationship between NP size and their impact on plant growth and biochemical activity, highlighting the significance of nanoparticle dimensions.

Conclusion:

The research demonstrated the potential of Ag, Cu, and Cu-Ag NPs to suppress thrips infestation, enhance plant growth, and stimulate biochemical activity in chili plants.

The findings suggest the promising application of chemical NPs in developing effective pesticides for combating thrips infestation, offering economic significance for chili crops.

The study provides valuable insights into the sustainable and cost-effective use of NPs to enhance chili plant productivity, which holds significance for industries relying on chili phytochemicals.

This research opens avenues for the development of sustainable agricultural practices, contributing to increased chili crop productivity and pest resistance through the strategic application of nanoparticles.

Reference:

MAWALE, K.S., NANDINI, B. AND GIRIDHAR, P., 2024. Copper and Silver Nanoparticle Seed Priming and Foliar Spray Modulate Plant Growth and Thrips Infestation in Capsicum spp. ACS Omega.