Selenium reduces cadmium accumulation and alleviates cadmium-induced quality degradation in tobacco

A greenhouse pot experiment was conducted using two contrasting tobacco cultivars Guiyan1 (Cd-sensitive) and Yunyan2 (Cd-tolerant) to evaluate the effect of external selenium (Se) on Cd-induced degradation of tobacco quality. Results showed that 3 mg/kg Cd reduced K, Mg, Mn, and Zn contents, but increased Cd, P, Ca, Fe contents in both cultivars. Addition of Se in Cd solution (Cd + Se) dramatically alleviated Cd-deteriorate effects on tobacco quality, markedly reduced Cd concentration, but increased Se and K contents in tobacco leaves compared with Cd alone treatment. Exogenous Se counteracted Cd-induced alterations in carbohydrate, e.g. it significantly depressed Cd-induced increase in total/reducing sugar, and sucrose contents, but elevated the reduced starch content. Furthermore, Se significantly depressed the elevated ratios in reducing sugar/total nitrogen, total sugar/total protein and reducing sugar/nicotine, but elevated total nitrogen/nicotine, which returned near to their control levels.