Effect Of Soil Cadmium On Sorghum Forages And Accumulation Of Cadmium In Different Sorghum Species

China is one of the countries which was most seriously polluted by heavy metal. As a highly toxic heavy metal, cadmium can entry into the soil and often accumulate on the surface but rarely move out, it is also impossible degradation like organic pollutants, and may migrate up because of plants. Sorghum plants is a kind of annual herb with tall stems, lush leaves, high resistance to drought, Waterlogging, high temperature, barren, salinity, pests and diseases, which was cultivated throughout the world. Sorghum forages growth status, physiological characteristics, accumulation and distribution of cadmium in Sorghum species were studied in this paper under different concentration of soil cadmium treatment, trying to explore the mechanism of Sorghum plants resistance to cadmium in the subcellular level. Discussing the poison effect of cadmium on Sorghum plants and the removing effect of Sorghum species to soil cadmium. With a view to provide some theoretical basis to soil remediation and food safety. The main results show as follow:1. The plant height, tiller number, regenerate height was improved under low concentration of Cd treatment but significantly decreased under high concentration of Cd treatment(P<0.05).2. Cd stress on chlorophyll synthesis was mainly manifested in the inhibition of chlorophyla synthesis; root activity was correlated negatively with the concentration of Cd at each growth stage; the proline content in leaves of the three kinds of Sorghum species were improved under low concentration of Cd treatment; the cell membrane permeability was significantly improved under Cd treatment.3. The MDA content in leaves was improved under low concentration of Cd treatment, but significantly decreased when the concentration of Cd more than 50 mg/kg. The CAT, SOD, POD activitives in different growth stage showed some changes under Cd treatment, but did not a similar phenomenon that the protective enzymes activity elevated under stress. The activity of protective enzymes in leaves of Sudangrass was higher than Sweet sorghum and Sorghum hybrid sudangrass on the whole.4. The NPT, GSH, PCs content in leaf, root and stem were significantly improved under Cd treatment, the NPT compounds induced by Cd stress mainly in the form of PCs.5. low concentrations of soil Cd improved fresh and dry matter yield of the three kinds of Sorghum species, but significantly decreased under high congcentration of Cd treatment.6. The Fe element in leaves and stems of the three kinds of Sorghum species increased first and then decreased, the Mn, Cu contents showed a similar trends as the Fe element. The Zn element in Sweet sorghum and Sudangrass increased first and then decreased under Cd treatment. It was not conducive to Zn absorption in Sorghum hybrid sudangrass under Cd treatment.7. The Cd content in the different tissues of the three kinds of Sorghum species was positively correlated with the concentration of Cd. The Cd accumulated in the roots of the three kinds of Sorghum species was higher than in stems and leaves. The subcellular distribution of Cd in leaves, stems and roots of the three kinds of Sorghm species were as follows: cell wall>soluble part >cell nucleus, chloroplast components > mitochondria. The NaCl-extractable form was the dominant form in the different tissues of the three kinds of Sorghum species under Cd treatment, the ethanol-extractable, water-extractable and acetic acid-extractable was relatively higher, but the hydrochloric acid-extractable and residual was relatively lower.