Abstract:
Lead (Pb) is an unimprtant toxic heavy metal that decreases agricultural productivity,
by impacting the physiological and biochemical properties of various crops. Lead
toxicity causes wheat productivity to plunder, by inducing oxidative stress in wheat.
Wheat is an essential part of human diet. It is a nesessary food for 50% of the global
population. Silicon is known to counter the adverse effcts of heavy metal toxicity. The
aim of this study was to synthesize common silica and nanosilica from rice husk and,
to observe their effect on wheat grown under lead contaminated soil. Rice husk was
leached with hydrochloric acid, and then rinsed with de-ionized water and after heating
it in muffle furnace at 700 °C, silica particles of nano size were obtained. Different
heating cycles were employed on rice husk to synthesize common silica particles.
Wheat was grown in pots containing 5 kg of lead contaminated soil to observe the
impacts of silica nanoparticles. Three different levels of common silica and nano-silica
particles (0, 300 and 500 mg/kg) were applied in the soil before one week of wheat
sowing. The lowest chlorophyll content, root weight, shoot weight and husk weight
were observed in the control plants while the highest lead concentrations in shoots,
roots, and grains were observed in the control plants. Common silica and nano-silica
particles improved wheat growth by increasing root, shoot and grain weight, and
counter oxidative stress in wheat by lowering hydrogen peroxide, electrolyte leakage
and malondialdehyde content in leaves. When compared with control, nano-silica
treatment reduced Pb concentration in wheat root, shoot and grain. This study indicates
that silica treatment improves the growth of wheat in a lead contaminated soil by
restricting its entry into wheat. NPs silica are more efficient in countering heavy metal
toxicity in wheat than bulk silica particles.
