Green synthesis of nanoparticles and nanoemulsions from allelopathic plants of Lower Himalaya and its evaluation for Antimicrobial Antifungal and Weedicidal efficiency

Abstract

newline xv newlineABSTRACT newlineIn the present study a very simple rapid, cost effective and environment friendly route was followed for the synthesis of silver and gold nanoemulsions using leaf extract of three allelopathic plants Azadirachta indica, Justicia adhatoda and Withania somnifera. The main focus of the study is to synthesis of nanoemulsions from allelopathic plants of Lower Himalaya and its evaluation for antimicrobial efficiency against E.coli, Bacillus subtilis, Klebsiella pneumoniae and Staphylococcis aureus; antifungal efficiency against Fusarium oxysorum and Rosellinia necatrix and weedicidal efficiency against three prominent weeds of Himalaya Ageratum conyzoides, Bidens pilosa and Parthenium hysterophorus. Qualitative and quantitative analysis of phytochemicals from leaf extract of allelopathic plants showed the presence of different phytochemicals in variable amount. Twelve combinations were made to check its efficiency in comparison to control. The combinations were Azadirachta silver nanoparticles; Azadirachta gold nanoparticles; Azadirachta silver nanoemulsion; Azadirachta gold nanoemulsion; Justicia silver nanoparticles; Justicia gold nanoparticles; Justicia silver nanoemulsion; Azadirachta gold nanoemulsion ; Withania silver nanparticles; Withania gold nanoparticles; Withania silver nanoemulsion and Withania gold nanoemulsion. The biosynthesized nanoparticles silver and gold nanoparticles were characterized by UV- visible spectroscopy, FT-IR, XRD and TEM analysis. The UV-visible spectrum of silver nanoparticles and nanoemulsion showed absorption maxima between 420nm - 440nm, respectively. Gold nanoparticles and nanoemulsion showed absorption maxima in between 520 nm - 540 nm. To know the presence of various functional groups in the synthesized gold and silver nanoparticles were confirmed by FT-IR spectra. TEM results showed the formation of deformed spherical nanoparticles of variable size. The results have shown that Azadirachta silver nanoemulsion showed maximum inhibition in growth parameters of weeds in seed germination and foliar spray bioassay. Azadirachta silver nanoemulsion also showed maximum inhibition in antibacterial and antifungal bioassay in comparison to the other combinations and glyphosate. The present study proposes that Azadirachta silver nanoemulsion a best formulation for the production of natural weedicide for weed management in Himalayan region. newlineKeywords: Nanoemulsion, green chemistry, weedicide, bactericide and fungicide.