[01] Kaiqiang Chu, School of Environmental & Safety Engineering, Changzhou University, Changzhou, China. [02] Yuankang Liu, School of Environmental & Safety Engineering, Changzhou University, Changzhou, China. [03] Rongyan Shen, School of Environmental & Safety Engineering, Changzhou University, Changzhou, China. [04] Jianguo Liu, School of Environmental & Safety Engineering, Changzhou University, Changzhou, China.

The effects of Nano-Silicon (Si) and common Si on the growth and Cd uptake in rice plants were studied under different soil Cd levels, and two rice cultivars of different cadmium (Cd) accumulation abilities were used. The results showed that the rice cultivars differed in Cd tolerance, and Yangdao 6 may be more sensitive than Yu 44 to soil Cd stress. The biomasses of the two rice cultivars were decreased significantly (P < 0.05) by 10 mg/kg soil Cd treatment. The alleviative effects of Si on Cd toxicities were higher for Nano-Si than for common Si, under 10 mg/kg soil Cd treatment than under 5 mg/kg soil Cd treatment, and in Yangdao 6 than in Yu 44. The effects of Si in reducing Cd concentrations of different rice organs were in the orders: Nano-Si treatment > common Si treatment, Yangdao 6 > Yu 44, 10 mg/kg soil Cd treatment > 5 mg/kg soil Cd treatment > Non-Cd-treatment, and grain > shoot > root. Under soil Cd stress (5 mg/kg and 10 mg/kg), grain Cd concentrations of two rice cultivars were reduced by 40.00% - 70.27% and 26.67% - 45.95% by Nano-Si and common Si respectively. Therefore, Nano-Si is superior to common Si in reducing Cd level of rice grain and alleviating Cd toxicities to rice growth in soil Cd pollution areas.

Rice (Oryza sativa L.), Silicon (Si), Cadmium (Cd), Uptake, Grain

[01] Dal Corso, G., Farinati, S., Maistri, S., Furini, A. (2008). How plants cope with cadmium: staking all on metabolism and gene expression. Journal of Integrative Plant Biology, 50: 1268–1280. [02] Toppi, L. S., Gabbrielli, R. (1999). Response to cadmium in higher plants. Environmental and Experimental Botany, 41: 105–130. [03] Mendoza-Cózatl, D., Loza-Tavera, H., Hernandez-Navarro, A., Moreno-Sanchez, R. (2005). Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants. FEMS Microbiology Reviews, 29: 653–671. [04] Horiguchi, H., Aoshima, K., Oguma, R., Sasaki, S., Miyamoto, K., Hosoi, Y., Katoh, T., Kayama, F. (2010). Latest status of cadmium accumulation and its effects on kidneys, bone, and erythropoiesis in inhabitants of the formerly cadmium-polluted Jinzu River Basin in Toyama, Japan, after restoration of rice paddies. International Archives of Occupational and Environmental Health, 83: 953–970. [05] Shimo, H., Ishimaru, Y., An, G., Yamakawa, T., Nakanishi, H., Nishizawa, N. K. (2011). Low cadmium (LCD), a novel gene related to cadmium tolerance and accumulation in rice. Journal of Experimental Botany, 62: 5727–5734. [06] Gong, H. J., Randall, D. P., Flowers T J. (2006). Silicon deposition in the root reduces sodium uptake in rice (Oryza sativa L.) seedlings by reducing bypass flow. Plant Cell and Environment, 29: 1970–1979. [07] Shetty, R., Jensen, B., Shetty, N. P., Hansen, M., Hansen, C. W., Starkey, K. R., Jørgensen, H. J. L. (2012). Silicon induced resistance against powdery mildew of roses caused by Podosphaera pannosa. Plant Pathology, 61: 120–131. [08] Mateos-Naranjo, E., Andrades-Moreno, L., Davy, A. J. (2013). Silicon alleviates deleterious effects of high salinity on the halophytic grass Spartina densiflora. Plant Physiology and Biochemistry, 63: 115–121. [09] Li, P., Song, A., Li, Z. J., Fan, F. L., Liang, Y. C. (2012). Silicon ameliorates manganese toxicity by regulating manganese transport and antioxidant reactions in rice (Oryza sativa L.). Plant and Soil, 354: 407–419. [10] Song, A. L., Li, Z. J., Zhang, J., Xue, G. F., Fan, F. L., Liang, Y. C. (2009). Silicon-enhanced resistance to cadmium toxicity in Brassica chinensis L. is attributed to Si-suppressed cadmium uptake and transport and Si-enhanced antioxidant defense capacity. Journal of Hazardous Materials, 172: 74–83. [11] Ali, S., Farooq, M. A., Yasmeen, T., Hussain, S., Arif, M. S., Abbas, F., Bharwana, S. A., Zhang, G. P. (2013). The influence of silicon on barley growth, photosynthesis and ultra-structure under chromium stress. Ecotoxicology and Environmental Safety, 89: 66–72. [12] Shi, Q. H., Bao, Z. Y., Zhu, Z. J., He, Y., Qian, Q. Q., Yu, J. Q. (2005). Silicon-mediated alleviation of Mn toxicity in Cucumis sativus in relation to activities of superoxide dismutase and ascorbate peroxidase. Phytochemistry, 66: 1551–1559. [13] Kaya, C., Tuna, A. L., Sonmez, O., Ince, F., Higgs, D. (2009). Mitigation effects of silicon on maize plants grown at high zinc. Journal of Plant Nutrition, 32: 1788–1798. [14] Rizwan, M., Meunier, J. D., Miche, H., Keller, C. (2012). Effect of silicon on reducing cadmium toxicity in durum wheat (Triticum turgidum L. cv. Claudio W.) grown in a soil with aged contamination. Journal of Hazardous Materials, 209– 210: 326–334. [15] Wu, J. W., Shi, Y., Zhu, Y. X., Wang, Y. C., Gong, H. J. (2013). Mechanisms of enhanced heavy metal tolerance in plants by silicon: A review. Pedosphere, 23: 815–825. [16] Liu, J. G., Zhu, Q. S., Zhang, Z. J., Xu, J. K., Yang, J. C., Wong, M. H. (2005). Variations in cadmium accumulation among rice cultivars and types and the selection of cultivars for reducing cadmium in the diet. J. Sci. Food Agric. 85, 147–153. [17] Liu, J. G., Qian, M., Cai, G. L., Yang, J. C., Zhu, Q. S. (2007). Uptake and translocation of Cd in different rice cultivars and the relation with Cd accumulation in rice grain. J. Hazard. Mater. 143, 443–447. [18] Wang, S. H., Luo, Q. S., Liu, C. P., Li, F. B., Shen, Z. G. (2007). Effects of leaf application of nanometer silicon to the accumulation of heavy metals in rice grains. Ecology and Environment, 16: 875–878. (in Chinese). [19] Jarup, L., Akesson, A. (2009). Current status of cadmium as an environmental health problem. Toxicol. Appl. Pharm., 238: 201–208. [20] Ali, S., Bai, P., Zeng, F., Cai, S., Qiu, B., Wu, F., Zhang, G. P. (2011). Ecotoxicological and interactive effects of chromium and aluminum on growth, oxidative damage and antioxidant enzymes of the two barley cultivars differing in Al tolerance. Environ. Exp. Bot. 70: 185–191. [21] Ali, S., Zeng, F., Cai, S., Qiu, B., Zhang, G. P. (2011). The interaction of salinity and chromium in the influence of barley growth and oxidative stress. Plant Soil Environ. 57: 153–159. [22] Ali, S., Cai, S., Zeng, F., Qiu, B., Zhang, G. P. (2012). The effect of salinity and chromium stresses on uptake and accumulation of mineral elements in barley genotypes differing in salt tolerance. J. Plant Nutr. 35: 827–839. [23] Ali, S.; Farooq, M. A., Hussain, S., Yasmeen, T., Abbasi, G. H., Zhang, G. P. (2013). Alleviation of chromium toxicity by hydrogen sulfide in barley. Environmental Toxicology and Chemistry, 32: 2234–2239 [24] Shahid, M., Dumat, C., Khalid, S., Niazi, N. K., Antunes, P. M. C. (2016). Cadmium Bioavailability, Uptake, Toxicity and Detoxification in Soil-Plant System. Reviews of Environmental Contamination and Toxicology, 241: 73–137. [25] Sanita, D. T., Gabbrielli, R. (1999). Response to cadmium in higher plants. J. Exp. Bot., 41: 105–130. [26] Zhang, F. Q., Zhang, H. X., Wang, G. P., Xu, L. L., Shen, Z. G. (2009). Cadmium-induced accumulation of hydrogenperoxide in the leaf apoplast of Phaseolus aureus and Vicia sativa and the roles of different antioxidant enzymes. J. Hazard. Mater., 168: 76–84. [27] Doncheva, S., Poschenrieder, C., Stoyanova, Z., Georgieva, K., Barceló, J. (2009). Silicon amelioration of manganese toxicity in Mn-sensitive and Mn-tolerant maize varieties. Environmental and Experimental Botany, 65: 189–197. [28] Liu, J. G., Zhang, H. M., Zhang, Y. X., Chai, T. Y. (2013). Silicon attenuates cadmium toxicity in Solanum nigrum L. by reducing cadmium uptake and oxidative stress. Plant Physiology and Biochemistry, 68: 1–7.