| Cadmium is mobile and strong toxic, resistant to degradation, which causes the environmental pollution getting worse. Cadmium also enters the body through the food and accumulates in the human body, serious harms to human health. Cadmium enrichment plant can effectively control soil cadmium pollution, so looking for the super-rich cadmium and adaptable plants have positive implications for soil cadmium pollution. In this study, there are three rice-producing areas(Hangzhou, Longhui, Nanjing) barnyard grass(Echinochloa crus-galli) as test subjects. Using outdoor potted studied, the stress of 7 concentration of cadmium(ck,0.3,0.6,0.9,1.5,3.0,6.0mg/kg) on barnyard grass tillering stage and heading stage physiological and biochemical parameters(antioxidant enzyme system(SOD, CAT,POD), chlorophyll, Pro, MDA, soluble protein) and mature biomass(tiller number, root length, plant height, roots and aboveground fresh weight and dry weight) and barnyard grass cadmium enrichment capability was studied. The results are as follows:(1) The effects of cadmium stressing on the physiological and biochemical indices of barnyard grass:a. Hangzhou barnyard grass tillering stage antioxidant enzyme activity with the increasing of concentrations of cadmium was increased and then significantly unaffected, at0.9mg/kg treatment, the activity is the strongest; 0.9 mg/kg and 6.0 mg/kg of cadmium stress,the content of MDA of plant increased significantly; only 6.0 mg/kg of cadmium stress cell osmotic adjustment was not significantly affected, which of other treatments were significantly decreased; photosynthesis significantly increased only at 0.3 mg/kg of cadmium stress, while others decreased significantly. In heading stage, only 0.3 mg/kg of cadmium stress, SOD activity was significantly enhanced, POD and SOD activity of other treatments decreased significantly, 0.6 mg/kg and 3.0 mg/kg of cadmium stress the overall activity of antioxidant enzymes was inhibited; MDA content of all cadmium stress treatment was significantly reduced; at 0.9 mg/kg and above cadmium stress, cell osmotic adjustment was significantly enhanced, most notably at 0.9 mg/kg of cadmium stress; With the increasing of the cadmium concentration, the photosynthesis increased first and then decreased after that increased and further decline, and it was strongest under 0.9 mg/kg of cadmium stress. Theresults showed that Hangzhou barnyard grass tillering stage under cadmium stress although photosynthesis was inhibited, but antioxidant enzyme activity was increased, which indicated good ability of anti-stress of the barnyard grass. In the heading stage, barnyard grass has been fully adapted to cadmium stress in the growth environment, and there are even stronger the trend contrasting to the control.b. Longhui barnyard grass tillering stage SOD activity with the increasing of concentrations of cadmium was increased and then decreased, 0.3 mg/kg of cadmium stress,the activity is the strongest, at 0.9mg/kg and above cadmium stress SOD activity was significantly reduced, CAT activity was significantly decreased only at 1.5 mg/kg of cadmium stress, POD activity of all cadmium stress was not significantly affected; barnyard grass were not affected by the stress of performance with cadmium stress, and the content of MDA was significantly reduced in the 1.5 mg/kg of cadmium stress; 0.6 mg/kg and 6.0mg/kg of cadmium stress cell osmotic adjustment were not significantly affected, at 0.3mg/kg of cadmium stress was significantly enhanced; photosynthesis with the increasing of the cadmium concentration enhancement, 1.5 mg/kg cadmium stress is the strongest, at 0.6mg/kg of cadmium stress was not significantly affected. In heading stage, only at 0.3 mg/kg of cadmium stress antioxidant enzyme activities were significantly decreased, 1.5 mg/kg and3.0 mg/kg of cadmium stress significantly increased the activity of SOD and POD, 0.9 mg/kg of cadmium stress, SOD activity was significantly increased; barnyard grass the content of MDA was significantly reduced with the stress only at 1.5mg/kg of cadmium stress, which of other treatments were not show the stress effects, and the content of MDA was significantly reduced in the 1.5mg/kg of cadmium stress; only 0.9mg/kg of cadmium stress cell osmotic adjustment was significantly enhanced; only 0.6mg/kg and 1.5mg/kg of cadmium stress,photosynthesis significantly reduced, which of others treatments were significantly enhanced.The results showed that Longhui barnyard grass exhibited good anti-stress ability of the cadmium stress, and the barnyard grass photosynthesis was enhanced, and the accumulation of biomass was promoted.c. Nanjing barnyard grass tillering stage SOD activity was significantly reduced at 0.3mg/kg and 0.9 mg/kg of cadmium stress,which of other treatments were significantly enhanced; only 0.9mg/kg of cadmium stress, CAT activity was significantly reduced and cellosmotic adjustment was significantly enhanced; POD activity, MDA and Pro content all of cadmium stress were not significantly affected, but the photosynthesis were inhibited, most notably at 0.3 mg/kg of cadmium stress. In heading stage, only at 1.5mg/kg of cadmium stress antioxidant enzyme activity was not significantly affected and cell osmotic adjustment was significantly enhanced; 0.3 mg/kg and 0.9 mg/kg and 6.0 mg/kg of cadmium stress,antioxidant enzyme activity and MDA content were significantly reduced, but the photosynthesis were significantly enhanced, which of other treatments the content of MDA is not significantly affected. The results showed that Nanjing barnyard grass tillering stage under cadmium stress although photosynthesis was inhibited, but it did not receive the stress effect, which indicated good ability of adapted to cadmium stress; in the heading stage,barnyard grass photosynthesis were enhanced under partial stressand, and the accumulation of biomass was promoted, showing good growth trend.(2)The effects of cadmium stress on barnyard grass biomass: All the concentration of cadmium stress barnyard grass tiller number, fresh weight and dry weight of root length,plant height, root and aerial parts were not significant influencd and showed no significant of the increasing trend.(3) Study the whole barnyard grass accumulation and the distribution of cadmium. The order of the accumulation ability of barnyard grass various parts to cadmium was: root >aboveground > grain. Under 6.0 mg/kg Cadmium stress, Hangzhou barnyard grass enrichment ability was the strongest, under 3.0 mg/kg cadmium stress, Nanjing and Hangzhou barnyard grass were the strongest enrichment capability, other low concentration,Longhui barnyard grass enrichment strongest. At 6.0 mg/kg of cadmium stress, roots enrichment factor was up to 5.56 of Hangzhou barnyard grass, at 3.0 mg/kg of cadmium stress, Nanjing barnyard grass 5.37. Transfer coefficient, Nanjing and Hangzhou barnyard grass was decreased with increasing concentrations of cadmium stress, but Hangzhou barnyard grass increased first and then decreased..Based on the above results obtained: In a certain range of concentrations of cadmium stress, barnyard grass has good resistance to stress, growth and development are not significant influence, showing a more vigorous growth trend with the increasing of the concentration of cadmium, with good roots enrichment capability. Therefore, barnyard grasscan be a plant to resolve the serious cadmium pollution soil. |
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