Synergistic Effect Of Plant On Strontium Enrichment Ability And Rhizosphere Promoting Bacteria

⁹⁰Sr is one of the main radioactive products for nuclear tests and nuclear power plant accident, whose half-life time is 29.1 years. With the rapid development and wide application of nuclear technology and the occurrence of nuclear accident, the content of strontium in the environment is increasingly high. And it is very hard to clear the strontium out. Once the nuclide come into the food chain, it will do harm to human health, therefore how to reduce the harm of radionuclide to human has great realistic significance to food security and the edible security of vegetables. A growing body of research is shedding light on soil radioactive pollution. Plant has already been one of the most important methods to reduce soil metal contamination since it can uptake, transport and accumulate metal. However, due to the normal growth of plants needs, there is always a danger threshold, therefore the application of phytoremediation is limited, thus it becomes very important to study the strengthening measures. At present there are many researches concerning about plant for strontium concentration, transfer and the influence of strontium on plant physiological and biochemical state, while there are few researches about the combined effects of microorganism and plant. The background levels of strontium is high in soil, thus we use water cultivation to exclude the many factors in soils. Furthermore, studies has shown that the steady and radiate state strontium is similar on chemical properties, inorder to obey the law and ensure the safety of the researchers, we use stable strontium instead of radioactive strontium to study the absorb and transfer laws of strontium from soil to plant and plant roots to other plant organs. The results are as follows:（1）The Sr taken up from the soil was mainly transported to the leavesand stems. With the increasing of Sr concentration in Hoagland solution, the TF in Chinese cabbage at 7,21 d and in rape at 7,14 d increased first and then decreased（P<0.05）. There is significant difference in different time and no interaction effect between group and time（P>0.05）.CR in the Chinese cabbage leaves and roots is decreased,and showed positive correlatelation （P<0.05）; CR in rape leaves at 21 d showed a downward trend after the first rise, the roots all decreased firstly and then increased, the CR of leaves and roots were analyzed by correlation, P< 0.05 meant statistical signification.（2） Compared with controls, the content of malondialdehyde（MDA） in Chinese cabbage decreased from the peak of 2 mmol/L with strontium concentration raised （P<0.05）, while there was no statistical significant difference between groups in rape（F=2.798, P> 0. 05）. Also, no statistical significant difference between the two vegetables （F=0.057, P>0.05）. The activity of superoxide dismutase, peroxidase and catalase decreased first and then increased （P< 0.05） The chlorophyll content in the 2 kinds of vegetables has statistical significant difference between groups（P< 0.05）, and compared with 7 d, the 14,21,28 d have statistical difference（P<0.05）.（3） The Plant Growth Promoting Rhizobacteria（PGPR） and Sr can effects the accumulation characteristics of Sr and chlorophyll concentration remarkably. With the increase of concentration of Sr,2 kinds of vegetable leaf chlorophyll content showed rised firstly and then decreased（P<0.05）; the concentration of Sr increased,except Chinese cabbage at 21 d reduced.