Mitigation Effects of Silicon on Maize Plants Grown at High Zinc

The effects of exogenous silicon (Si) on key growth parameters and mineral nutrients were investigated in maize grown at high zinc (Zn). Four treatments with three replicates were investigated consisting of a control (basal nutrients with 0.05 mM Zn with or without 1.0 mM Si added), 0.5 mM Zn, and 0.5 mM Zn plus 1.0 mM Si. Plants growing with high Zn alone had a lower chlorophyll (Chl.) content, leaf relative water content (RWC) and produced less biomass than the control plants. Proline content and membrane permeability was higher in zinc-treated plants than in untreated controls. Compared with the plants treated with high Zn alone, added Si significantly increased plant growth, chlorophyll content, and RWC and significantly reduced the membrane permeability and proline content. As expected, added high Zn increased leaf and root Zn, but reduced leaf phosphorus (P) and iron (Fe). Added Si reduced Zn concentration and increased Fe in leaves of maize. It can be concluded that improvement in the key growth parameters tested and mineral nutrition status in maize plants grown at high Zn induced by Si addition may protect membrane permeability under high zinc, thus mitigating Zn toxicity and improving the growth of maize plants. The results of the present experiment support the conclusion that Si may be involved in physiological and nutritional changes in plants grown at high Zn