Maryam Mazaheri-Tirani

The present study investigated the effect of nano/microparticles zinc oxide (ZnO-NPs/MPs) on root, vegetative, and flowering induction in medicinal plant Trachyspermum ammi. Powdered ZnO-NPs/MPs were added to soil in concentrations 0, 250, 500, and 1000 mg kg–1. Plants root/shoot weight and length, water content, umbellate and flowers, chlorophyll, carotenoid, oxidants (H2O2, MDA), antioxidants (anthocyanin, phenolics, SOD) were measured. Shoots appeared to be more sensitive to NPs than MPs treatments. ZnO NPs/MPs treatments caused a more consistent result on water content. ZnO-NPs/MPs 500, and 1000 mg kg–1 resulted in toxic responses. ZnO-NPs toxicity effects on growth parameters were more significant than that of MPs, especially on chlorophyll. The decrease in phenolic compound was compensated with increased anthocyanin content under ZnO-NPs/MPs. Both forms of ZnO at all concentrations resulted in zinc content increase compared with the control. ZnO-NPs/MPs 250 mg kg–1 increased plant fresh/dry weight and length of shoots and roots, total chlorophyll, protein and zinc content while reduced oxidant contents. Plants revealed stressed conditions while preferred a non-enzymatic response under NPs. plants’ zinc content under NPs was almost similar to micro-treatments. NPs at lower concentrations induced vegetative growth but had a negative effect at higher concentrations. MPs reduced root growth while increased flowering induction.