Development Of Nanomaterials For The Management Of Colletotrichum Truncatum Causing Anthracnose In Chilli

Abstract

The application of nanotechnology in agriculture has revolutionised the sector with its newlineunique properties. Among the different methods of nanoparticle synthesis, green newlinenanoparticles that do not use any toxic chemicals in the synthesis process garner interest newlineworldwide. The promising progress made in the field has encouraged researchers to explore newlinedifferent biological materials for nanoparticle synthesis. In the present work, silver newlinenanoparticles (Ag NPs) were synthesised using extracellular extract (Phytophthora infestans), newlineplant extracts (mango peel, dragon fruit peel and Basella alba L. mucilage) and biopolymers newline(chitosan- both silver and gold nanoparticles) as reducing, capping, and stabilising agents in newlinethe synthesis process. The synthesis was done at a high temperature in an alkaline condition. newlineThe synthesis of nanoparticles was observed by a change in the colour of the solution to newlineyellow for silver nanoparticles (AgNPs) and ruby red for gold nanoparticles (AuNPs). The newline newlinecharacterisation of the synthesised nanoparticles was done with various analytical (Uv- newlineVisible Spectroscopy, XRD, FTIR and zeta potential measurements) and microscopic newline newlinetechniques (FESEM/TEM, EDX). The UV-Visible spectroscopy of synthesised nanoparticles newlineshowed a surface plasmon resonance peak between 400 420 nm (for AgNPs) and 520 nm newline(AuNPs). The synthesised silver nanoparticles were small, and the average particle size newlinedistribution was from 4 to 40 nm, as characterised by TEM and FESEM. EDX confirms the newlinepresence of silver and silver chloride among the principal elements. The XRD spectra showed newlinethe crystalline nature of synthesised silver and silver chloride nanoparticles. The FTIR newlineanalysis showed the interaction of nanoparticles with the respective substrate materials used newlinefor the synthesis. newlineChilli anthracnose is selected as a plant-pathogen system model for evaluating the newlineantifungal activity of the synthesised nanoparticles. The fungicidal efficacy of green newlinesynthesised nanocomposites was tested against Colletotrichum truncatum (syn. C. capsisi), newlinecausing anthracnose in chilli. The synthesised nanoparticles showed antifungal activity newlineagainst C. truncatum spores in both in vitro conidial germination and spread plate assays. The newlinesilver nanoparticles synthesised using different extracts, and chitosan showed inhibition of newlinespore germination and appressorial formation at as low as 0.0005%. In contrast, chitosan gold newlinenanocomposite did not show antifungal activity. In vivo assay of chitosan silver newlinenanocomposite using detached chilli fruit (Capsicum annuum) showed that nanocomposite newlinesignificantly inhibited anthracnose in both preventive and curative treatments. The newline newlineIX newline newlinenanocomposites exhibited growth-promoting activity with chilli seeds. Therefore, the newlinesynthesised nanocomposites have the dual benefit of growth promotion and an effective newlineantifungal agent in preventing postharvest anthracnose disease in chilli. The current study newlinefinds an interesting application of nanomaterials to effectively manage pre and postharvest newlinediseases associated with C. truncatum. newline