Se nanoparticles stabilized with Allamanda cathartica L. flower extract inhibited phytopathogens and promoted mustard growth under salt stress

Selenium Nanoparticles (SeNPs) exhibit tremendous application in agriculture as antimicrobials or as nano fertilizer. Present work reports the eco-friendly synthesis of SeNPs by using Allamanda cathartica L. flower extract (aqueous) as a reducing/capping agent and selenium dioxide as a precursor. The method used here is free of any toxic reducing agents and organic solvents. The synthesis process of SeNPs took 5 h at 60 °C, confirmed by the brick red colour of the solution followed by UV-Vis spectroscopy and further characterized by XRD, FTIR, EDX and SEM. The average size (diameter) of the SeNPs were found to be 60.31 nm by DLS. It has shown strong antimicrobial activity against Pseudomonas marginalis and P. aeruginosa at 2.5, 5 and 10 mg/mL concentrations. Besides, its application improved seed germination and growth parameters of Brassica campestris (TS 36 variety) under salt stress. 25 mg/L SeNPs has improved the germination percentage by around 31%, shoot length by 92%, root length by 78% and total chlorophyll content by 49% under 200 mM NaCl stress. This SeNPs could be a potential antimicrobial agent in treating plant diseases caused by the mentioned phytopathogens, having no or minimum toxicity, in fact having positive impacts on plant growth.