The Effect of potassium source on reducing cadmium stress and cadmium uptake by canola (Brassica napus L.)

  The increase in population and the increase of scientific and technical knowledge and the development of industries without observing environmental issues and standards has contributed to the pollution and collapse of the soil biomass balance. Cadmium is a heavy metal, an inessential and toxic element for plants that it enter to the earth by different human activities. Phytoremediation is one of the more efficient proposal methods in pollution effacement. The advantage of Phytoremediation is adding organic, nutrient elements and oxygen to the soil that improve the quality and structure of the soil in purging places. Plants also, create a cover for the soil and their roots stabilize the soil and thus reduce the wind and water erosion. There are reports about potassium fertilizer with plants for absorption of cadmium and Phytoremediation preferment. The cadmium ion can formed by permanent complexes with chloride quickly. Chlorides are very fluid and can be an important factor in cadmium distribution of the soil in the specific conditions. The aim of this research is investigation the effect of using chloride and potassium sulfate fertilizer to absorption of cadmium and Phytoremediation preferment by canola plant. This research performed into factorial and completely random design with 4 potassium levels (0, 100, 200 and 300 mg/gr K2O) from sources of potassium chloride and potassium sulfate, separately and 3 levels of cadmium (0, 15 and 30 mg/kg) from the source of cadmium nitrate in 3 replications at canola plant in glasshouse of center research. As far the results of analysis of variance of effects of Cadmium and Potassium fertilizers and their interaction have significant effect on the amount of Cadmium of root and shoot, root dry weight and Potassium of root. Also, according to the results, the main effects of cadmium and potassium fertilizers have significant effect on dry weight and Potassium of shoot, whereas the effect of their interaction on dry weight and Potassium of shoot isn’t significant. In the treatment of 15 mg/kg, at 200 and 300 mg/gr levels of Chloride Potassium and 300 mg/gr level of Potassium sulfate into control, increase the content of Cadmium of the root but the content of Cadmium in shoot in 200 and 300 mg/gr levels of Chloride and Potassium sulfate into control increase significantly. The results of interactions in levels of Cadmium and Potassium fertilizers on dry weight of root show that highest amount of the dry weight of root exists in 0 Cadmium treatment (control) in 200 mg/gr level of Potassium sulfate and the lowest amount of dry weight of root has been observed in 30 mg/Kg Cadmium treatment on 300 mg/gr Potassium sulfate level. Highest and lowest amount of dry weight of shoot is related to the control treatment of Cadmium and 30 mg/Kg Cadmium treatment respectively. Also the result of Cadmium treatment shows that the Potassium of shoot decrease significantly with increasing of Cadmium and all levels shows the significant reduction. Highest and lowest amount of Potassium of shoot is related to the 0 level of Cadmium and 30 mg/Kg level of Cadmium respectively. Investigation of the levels of Potassium fertilizers show that adding Potassium fertilizer increase the absorption of the Potassium of shoot has been observed in 300 mg/gr level of Potassium sulfate. In this research, there is significant difference between Potassium fertilizers (sulfate and chloride Potassium), whereas highest amount of the absorption of Cadmium has been observed in 300 mg/gr level in chloride Potassium, so according to the results of the glasshouse experiment, the efficiency of Phytoremediation improved however continuity of researches seem to be imperative in the farm conditions