| In soil-plant system, the transfer factor(TF) of Cd is the indicators of the effectiveness of soil Cd and Cd accumulation capacity of plant from soil. The transport capacity of Cd can be affected by its forms and the properties of soil. The aims of the study are to obtain the main controlling factors and establish prediction models by analyzing the transfer rule between the properties of the soil and the Cd in tomato. Basing on the Freundlich expansion equation, the correlation coefficient between the TF of the Cd between tomato and soil and the soil properties can be obtained. Combining soil Cd, and the interaction between soil Cd and hydrogen ion activity greatly improved the model to predict the transfer of Cd from soil to plant. The prediction equations are as follows: [Cd]plant = 0.022 + 0.043×107 [H+] [Cd]soil + 0.635[Cd]soil(Adj. r2 = 0.972,p < 0.001)There are different equations between different souices of soil Cd and plant Cd. The results showed that the interaction between hydrogen ion activity and soil Cd had significant influence on the Cd concentration in plants. The correlation between plant Cd and soil added Cd was higher than that for soil total Cd. Soil added Cd was introduced to exclude the influence of soil background Cd and use to calculate Cd transfer from soil to plant. The higher correlation between plant Cd and soil added Cd indicated a better representation of the Cd transfer characteristics. Combining soil Cd, and the interaction between soil Cd and hydrogen ion activity in the prediction equation greatly improved the correlation performance and could be used to predict the transfer of Cd from soil to plant. This predicted model has important significance for predicting Cd transfer from soil to plant.In the experiment, Cd concentrations were 0.01 mg·L-1(low dose), 0.03 mg·L-1(medium dose), 0.09 mg·L-1(high dose), and 0 mg·L-1(control); and exogenous Zn were 0.025 mg·L-1, 0.05 mg·L-1, 0.1 mg·L-1, 0.2 mg·L-1. The aim of the study was to determine the mechanism of interactions between Zn and Cd and to identify the optimal Zn concentration that effectively reduced Cd pollution in rice. Thus under medium-to-low dose Cd conditions, Zn controlled the phyto-availability of Cd due to obvious antagonistic effects between Zn and Cd. Application of 0.05 mg·L-1 Zn significantly reduced Cd phyto-availability and migration in rice and maximally increased plant biomass under low concentrations of Cd in hydroponic cultures.Under medium-to-low dose Cd conditions, the yield increased due to applying different kinds of passivator(red mud(RM), rape straw(RS), corn straw(CS)) to the soil. Every treatment could significantly reduce the concentration of the Cd in spinach; among them the treatment using red mud with rape straw(RM+RS) is significantly better than other treatments. Compared with the result of seven years ago, the passivation effect still remains at 28%. Thus, the complex passivator can significantly increase crop yield and can effectively reduce the plant availability of the Cd. It has a lasting and stable effect. The field experiment in Ji Nan station was implemented basing on that in De Zhou station. Compared with other passivators, the complex passivator(RM, RS, Zn fertilizer, Amino acid solution) can effectively reduce the plant availability of the Cd. It can promote the water soluble of the Cd and the exchangeable Cd to be the EDTA- Cd which was more stable. It can effectively reduce the plant availability of the Cd.Under medium-to-low dose Cd conditions, the complex passivator(RM, RS, Zn fertilizer, Amino acid solution) can effectively reduce the plant availability of the Cd and the effective state of the Cd in the soil. The poisoning risk of the Cd was reduced by this way. Joint application of inorganic immobilization agent red mud, cruciferous rape straw, zinc fertilizer and amino acid solution is an efficient and eco-friend method for repairing Cd pollution. |
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