Effects Of Soil And Foliar Regulation Methods On Cadmium Pollution In Yellow-Red Paddy

Heavy metal pollution is a severe problem that straitens land improvement and food safety in China.In this study,Rice cultivar G Liangyou 9815 was used to study the mitigation effect of different soil and foliar regulation methods on cadmium pollution to rice in acidic yellow-red soil through rhizo-box experiment.The main results are as following:1.Application of calcareous alkaline modifier can relieve cadmium pollution to rice in acidic yellow-red soil,and 1.50 g/kg calcareous alkaline modifier is better than 0.75 g / kg calcareous alkaline modifier.Compared with the cadmium contaminated control,application of calcareous alkaline modifier can enhance the rice growth,increase tiller number and plant height significantly and the rice pollen developed better.Furthermore,the yield of rice increased by more than 13.85%,1000-seed weight increased by more than 8.13%,the dry weight of above-ground increased by more than 7.33%,and the cadmium concentration of white rice reduced significantly and was lower than the national food safety limit standard?GB2762-2012?.The application of calcareous alkaline modifier also increased the p H in acidic yellow-red soil,decreased the cadmium availability of soil,and increased the exchangeable calcium and magnesium in soil.Compared with the cadmium polluted control,the soil p H increased by at least 0.10 after adding calcareous alkaline modifier,the exchangeable cadmium in the rhizosphere soil decreased by 4.21% 6.18%,and the ratio of residual cadmium to the total cadmium reached to the peak and increased by 4.23%.Moreover,the exchangeable calcium in the rhizoshpere soil increased by 6.84% and the exchangeable magnesium increased by 7.95% after adding calcareous alkaline modifier.2.Addition of wheat or rape straw can alleviate the cadmium pollution to rice in acidic yellow-red soil,but the wheat straw is better than the rape straw.Compared with the cadmium contaminated control,adding 8g/kg of wheat straw or 8g/kg rape straw increased rice yield by 12.92% and 13.57%,and the 1000-grain weight by 15.50% and 6.97% respectively.But decreased the cadmium concentration in the white rice significantly which was lower than the national food safety limit standard?GB2762-2012?.The SEM figures showed the rice pollen developed better and the dehydration phenomenon improved remarkably with the addition of wheat or rape straw.The exchangeable cadmium in the acidic yellow-red soil decreased by 4.02% and 3.78% while the residual cadmium increased by 4.29% and 3.21% respectively after adding wheat or rape straw.In addition,the amendment of wheat straw also increased the available phosphorus in the acidic yellow-red soil by 33% as compared with the control treatment.3.Compared with the cadmium contaminated control,adding 1 % of fertilizer enhancer reduced the concentration and accumulation of Cd in white rice significantly.The Cd concentration of white rice was similar to that of adding 1.5 g/kg calcareous alkaline modifier,and the total Cd in the white rice was the smallest in four soil regulation methods.However,1 % of fertilizer enhancer can not decrease the Cd availability in acidic yellow-red soil.4.Compared with the cadmium contaminated control,using potassium sulfate as potassium fertilizer can not mitigate cadmium pollution to rice in acidic yellow-red soil.This may be due to the rhizo-box in the experiment can not keep the rice in a flooded environment with a relatively low redox potential for a long time.5.2% of NaH₂PO₄,2% of Na₂SiO₃,2% of Na₂SO₄ and 500 times of Shidijia dilution were used through foliage spray,the results showed that 2% Na H2PO4 is better than other three foliage reagents.Compared with the cadmium contaminated control.The yield of rice increased by 16.31%,12.39%,6.62% and 14.42% respectively by spraying 2% of NaH₂PO₄,2% of Na₂SiO₃,2% of Na₂SO₄ and 500 times of Shidijia dilution.The effective panicles increased by 64.28%,42.86% and 53.71% respectively,and 1000-grain weight increased by 11.82%,17.10%,2.62% and 8.87% respectively.Furthermore,the rice pollen developed better after spraying 2% of NaH₂PO₄ or 2% of Na₂SO₄,and the cadmium concentration of white rice also reduced significantly and was lower than the national food safety limit standard?GB2762-2012?.According to rice grain yield,white rice Cd concentration and soil Ca availability,1.50 g /kg of calcareous alkaline modifier or 8g / kg of wheat straw showed better mitigation effect of cadmium pollution to rice in acidic yellow-red soil in four supplied soil regulation methods.And spraying 2% of NaH₂PO₄ was better than spraying 2% of Na₂SiO₃,2% of Na₂SO₄ and 500 times of Shidijia dilution in terms of rice grain yield and white rice Cd concentration...