the efficacy of solid and enriched biochars with magnesium and iron nanoparticles on growth and essential oil composition of german chamomile under salt stress

Objective: this research was aimed to observe the effects of solid and enriched biochars with magnesium and iron nanoparticles on the growth and essential oil composition of german chamomile.methods: a factorial experiment based on a randomized complete block design with three replications was conducted to study the potential effects of solid biochar (25 g kg-1 soil) and biochar-based nanoparticles (bnps) of magnesium oxide (25 g bnp-mgo kg-1 soil), iron oxide (25 g bnp-fe3o4 kg-1 soil), and their combined form (12.5 g bnp-mgo + 12.5 g bnp- fe3o4 kg-1 soil), on root and shoot masses and essential oil composition of chamomile under non-saline and saline (6 and 12 dsm-1) conditions in a greenhouse at the university of tabriz, iran during 2021.results: salinity caused a decrease in root and shoot masses and root/shoot ratio, but the application of biochar, especially bnps, improved the root and shoot growth. the bnp-fe3o4 under both salinity levels and bnp-mgo + bnp- fe3o4 only under high salinity (12 dsm-1) increased the root/shoot ratio. enriched biochars also enhanced most of the essential constituents of chamomile flowers, compared to the solid biochar. the bnps were superior treatments in reducing the adverse effects of salinity on plants. forty-eight constituents were identified in the essential oil, some of which were only produced by bnps and salinity treatments. azoline, trans-β-farnesene, bisabolol oxide a, and bisabolone oxide were the major constituents of essential oil. production of oleic and hexadecanoic acids was only induced by salt stress. however, the juniper camphor, e-citral, z-citral, geranic acid, aromadendrene, and sesquisabinene were distinctly synthesized under enriched biochars.conclusion: the application of bnps can boost the essence production of chamomile by enhancing plant growth and most of the essential oil constituents under various salinity levels.