Effects Of Cadmium Ion Availability On Absorption Of Cadmium By Rice

Cadmium pollution in soil and agricultural products is a worldwide problem.Hunan Province is one of the largest rice producing areas in China,at the same time,Hunan province is one of the most heavily polluted provinces.Therefore,the comprehensive control of cadmium contaminated rice field,especially in the mild pollution of soil in situ treatment is one of the important emergency measures to reduce the cadmium content of rice.But so far,it is lack of in-depth research and systematic evaluation that products which can reduce the cadmium affect the availability of cadmium in soil and the cadmium absorption of rice.In this study,we use G283、9311、Luliangyou996、Xiangwanxian12、KT27s、T91s、Zhuliangyou819 as materials to explore their influence under different cadmium affinity materials of rice.The purpose is to provide the theoretical basis and technical support for agricultural production related to the cadmium reduction.The main results are as follows:1、The addition of EDTANa₂,Na₂SH,soil conditionerⅠ,soil conditionerⅡ,soil conditionerⅢ,alkaline granule fertilizer,biological fertilizer and kaolin could significantly reduce the shoot cadmium content of rice seedlings under the condition of 5umol/L Cd²⁺.The addition of EDTANa₂ and alkaline granule fertilizers reduced the shoot cadmium content of rice seedlings by more than 50%.Whereas,NH₄Cl and CH₃COONH₄ did not significantly affect the Cd uptake and transport by rice seedlings.2、High cadmium absorption variety Luliangyou996 and low cadmium absorption variety Zhuliangyou819 were planted in soil with the cadmium content of 1.4mg/kg.Compared with the control,under the treatment of EDTANa₂,soil conditionerⅠ,soil conditionerⅡ,soil conditionerⅢand biological fertilizer,the contents of cadmium were significantly decreased in rice’s root,stem,leaf,chaff and brown rice.The effect of these passivation fertilizers on reducing cadmium content in grains was EDTANa2>soil conditionerⅠ,soil conditionerⅡ,soil conditionerⅢ>biological fertilizer.The application of NH₄Cl and CH₃COONH₄ can increase the activity of cadmium in soil,leading to a significant increase in cadmium content in various parts of rice.3、High cadmium absorption variety G283 and Low cadmium absorption variety Xiangwanxian12 were planted in soil with the cadmium content of 1.4mg/kg.under the treatment of soil conditionerⅠ,soil conditionerⅡ,soil conditionerⅢ,the contents of cadmium were significantly decreased in rice’s root,stem,leaf,brown rice and they have no negative influence on the growth and fruiting trait of rice.The effect of these soil conditioner on reducing cadmium content in grains was soil conditionerⅢ>soil conditionerⅠ>soil conditionerⅡ.4、The efficiency of Cd uptake,enrichment and transport was related to genotype.The content of cadmium in root,stem,leaf,chaff and grain of Luliangyou996 was significantly higher than that of Zhuliangyou819.The content of cadmium in root,stem,leaves and grain of G283 was significantly higher than that of Xiangwanxian125、At the same cadmium concentration,there were significant differences in cadmium absorption between different rice cultivars,among which the shoot and root of G283 had the highest amount of cadmium,while T91s and Zhuliangyou819 had the least amount of cadmium.The cadmium content in the shoot and root of G283 seedling increased significantly with the increase of cadmium concentration.When the concentration of cadmium was less than25umol/L,the cadmium accumulated mainly in the Xiangwanxian12’s root,when the cadmium concentration increased,the cadmium transported up significantly increase.Compared with Luliangyou996,when the concentration of cadmium increased to 20umol/L,the accumulation of cadmium increased significantly at the Zhuliangyou819’s root and the cadmium content in the shoot increased slowly.