Effects of nano-silicon and common silicon on lead uptake and translocation in two rice cultivars

The current study investigated the effects of nano-silicon (Si) and common Si on lead (Pb) toxicity, uptake, translocation, and accumulation in the rice cultivars Yangdao 6 and Yu 44 grown in soil containing two different Pb levels (500 mga (TM) kg(-1) and 1000 mga (TM) kg(-1)). The results showed that Si application alleviated the toxic effects of Pb on rice growth. Under soil Pb treatments of 500 and 1000 mga (TM) kg(-1), the biomasses of plants supplied with common Si and nano-Si were 1.8%-5.2% and 3.3%-11.8% higher, respectively, than those of plants with no Si supply (control). Compared to the control, Pb concentrations in rice shoots supplied with common Si and nano-Si were reduced by 14.3%-31.4% and 27.6%-54.0%, respectively. Pb concentrations in rice grains treated with common Si and nano-Si decreased by 21.3%-40.9% and 38.6%-64.8%, respectively. Pb translocation factors (TFs) from roots to shoots decreased by 15.0%-29.3% and 25.6%-50.8%, respectively. The TFs from shoots to grains reduced by 8.3%-13.7% and 15.3%-21.1%, respectively, after Si application. The magnitudes of the effects observed on plants decreased in the following order: nano-Si treatment > common Si treatment and high-grain- Pb-accumulating cultivar (Yangdao 6)> low-grain-Pbaccumulating cultivar (Yu 44) and heavy Pb stress (1000 mga (TM) kg(-1))> moderate Pb stress (500 mga (TM) kg(-1))> no Pb treatment. The results of the study indicate that nano-Si is more efficient than common Si in ameliorating the toxic effects of Pb on rice growth, preventing Pb transfer from rice roots to aboveground parts, and blocking Pb accumulation in rice grains, especially in high-Pbaccumulating rice cultivars and in heavily Pb-polluted soils.