Exogenous application of silicon at the boot stage decreases accumulation of cadmium in wheat (Triticum aestivum L.) grains

A pot experiment was conducted to assess role of added silicon (Si) in alleviating cadmium-induced oxidative stress in wheat cultivars (AARI-2011, Cd-sensitive and FSD-2008, Cd-tolerant). Plants were exposed to different levels of CdCl2 (0, 25, 50, and 75 mu M Cd/kg) along with sodium silicate (0 and 1.5 mM) at the boot stage. Cadmium stress resulted in a marked decline in various growth attributes, photosynthetic pigments, and the activities of some enzymatic antioxidants, particularly in Cd-sensitive wheat cultivar. Application of Si reduced Cdmediated oxidative stress and increased photosynthetic pigments and proline contents in both wheat cultivars. Although Si application affected the shoot and grain Cd2+ concentrations differently in both cultivars, it decreased Cd2+ concentrations in the grains in both wheat cultivars. However, at higher Cd2+ concentrations, Si was very effective in decreasing Cd2+ concentrations in the grains of Cd-tolerant cultivar. The alleviatory effects of Si on Cd2+ concentrations in grain could be attributed to the altered Cd2+ uptake and translocation, particularly at higher Cd2+ concentrations in both wheat cultivars. The effectiveness of Si to reduce grain-Cd2+ concentrations in diverse wheat cultivars suggested its use as soil amendments in the Cd-polluted environments.