Friday, October 11, 2013

Effect of foliar spraying acid rain on Cd concentration of peanut grains

Peanut was harvested at maturity. Plant material was digested with nitric and perchloric acids
(5:1). Grain material was first carbonized in a heating plate (200-220?), and then ashed in a
muffle furnace at 500 for 6 h. After cooling, the ash was dissolved with 0.5 mol/L of nitric acid and filtered with quantitative filter paper. Cd contents in the solutions were measured by atomic absorption spectrophotometry

It shows the concentration of Cd in peanut grains at maturity. No significant difference of Cd concentration in grains was found with spraying pure water at any stage (the control). The average concentration of Cd in grains of Yuhua-15 was 0.070 mg/kg in the control, which was significantly higher than that of Huayu-23 (0.031 mg/kg, averagely). The concentrations of Cd in
grains were significantly increased by foliar spray of acid rain at each stage. In which, Cd concentrations in the grains of Yuhua-15 increased by 84%, 26%, 23% and 1% for treatments of spraying at seedling, flowering, podding, and fruit filling stages, respectively, with comparison of the control. While Cd concentrations in the grains of Huayu-23 increased by 229%, 116%, 126% and 90% respectively for treatments of spraying at the above mentioned stages, compared with the control. Overall, the increasing rate of Cd concentration in peanut grains decreased with the delay of spraying acid rain. No matter what time spraying, the absolute grain Cd concentrations of Yuhua-15 were significantly higher than that of Huayu-23, however, the increasing rate of grain Cd concentration of Huayu-23 was significantly higher than that of Yuhua.

Relationship between Cd concentration in the vegetative organs and grains he results in Table 3 shows that, with delay of the time of spraying, Cd concentrations of the vine stems and leaves increased, while Cd concentrations of the roots and pods decreased gradually. There was a positive relationship between Cd concentration of the roots and grains  and a negative relationship between Cd concentrations of the vine stems, leaves and grains .

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