Imobilization Of Heavy Metal Pollution In Sorghum Plants

Heavy metal pollution of soil is usually related to human activities. Sites near mining activities or heavy industry are often highly contaminated with toxic metals. Besides, application of low-quality fertilizers contaminated with heavy metals, e.g. cadmium, increased metal content in top-soils (Lado et al., 2008). Such highly polluted soils are hardly usable for agricultural purposes, because the pollution can be transferred into the food chain. Heavy metals bounded in the soil are leachable, they can be also spread via ground water. To avoid the danger of contaminant spread, it is possible to use phytoremediation techniques, which can immobilize pollutant, decreasing the soil or water pollution (Salt et al., 1998). Plants are able to immobilize metals in soil by formation of

Sorghum plants are multipurpose cereals of potential interest for several non-food uses, especially as energy crops (Barbanti et al., 2006; Meki et al., 2013). The crop is resistant to drought, heat stress, and toxic pollution. It was shown that sorghum plants were able to accumulate large quantities of Cd, Cu, Pb, and Zn in the shoots and their biomass production was higher than that of sunflower or corn (Epelde et al., 2009; Zhuang et al., 2009). Moreover, other studies demonstrated that sorghum plants were highly tolerant to metal pollution and able to reach high biomass, even in the presence of heavy metals (Pinto et al., 2004; Hernández-Allica et al., 2008; Angelova et al., 2011). Only few studies have dealt with practical applications. A field trial with sorghum plants was located near the lead and zinc mining site in China (Zhuang et al., 2009). Another field trial was in Bulgaria near non-ferrous-metal works. All plants accumulated heavy metals primarily in roots, however, relatively high amount of Cd was found in stems of Sudan grass (Angelova et al., 2011). Experiments were also focused on heavy metal polluted marginal