Foliar Application of Nano-Silicon Complexes on Growth, Oxidative Damage and Bioactive Compounds of Feverfew Under Drought Stress

Drought stress limits the growth and yield of essential oils of valuable medicinal plants such as feverfew (Tanacetum parthenium). So, foliar application efficiency of nano-silicon complexes (glycine-nano-silicon, histidine-nano-silicon, glutamine-nano-silicon) was assessed on the growth and yield of feverfew, in a 120-day period of drought stress that was imposed by different irrigation gaps (4, 8 and 12 days). Nano-silicon compounds were sprayed on plants at three concentrations (zero-control, 1.5 and 3.0 mM) at 10-day intervals. The results showed that with increasing intensity of drought stress, leaf water saturation, accumulation of hydrogen peroxide and malondialdehyde increased and membrane damage in the leaf developed. With the loss of leaf water content and the development of oxidative damage, biomass accumulation, leaf area, the number of flowering branches in the plant decreased. Under severe drought stress, antioxidant capacity, phenol accumulation and essential oil yield decreased. The application of nano-silicon complexes limited tissue dehydration (35%) and the development of oxidative damage (30%) under drought stress conditions and restored the growth (25%) and yield of plant essential oils (30%). There was no significant difference between 1.5 and 3.0 mM nano-silicon compounds in most of the evaluated indices and glycine-nano-silicon combination was most effective in increasing plant drought tolerance.