Effects Of Water Management With Elevate CO₂、Immobilizing Agents On Development And Cadmium Uptake Of Rice

Under the conditions of global climate change,There was interaction effect between CO2 elevation,Cd pollution and drought on rice growth,absorption and enrichment of Cd and so on.However,the effect of CO2 elevation,Cd pollution and drought on the growth,absorption and accumulation of Cd in rice is rarely reported.Therefore,this study simulates drought at different growth stages through water management,and control the concentration of CO2 with OTC.Investigated two kinds of CO2 concentration(AC,380 μL L-1;EC,760 μL L-1)5 types of water management(Flooded,Aerobic,Aerobic 10d before heading stage,Aerobic 10d after heading stage,Aerobic in milk stage).Study the effects on growth,Cd content in different parts of two rice varieties(terYou 524 and Y two you 696),pH of rhizosphere soil and Cd/Fe/Mn content of iron Iron plaqu of root surface.And then,The effects of 16 kinds of Immobilizing agents and 3 kinds of water management on the photosynthesis rate and the growth of Y two-you 696,the content of Cd in the rice,the pH of the rhizosphere soil and the effective state Cd,and the content of the Cd/Fe/Mn content in the iron film of the root were studied.The following conclusions are obtained(1)The increase of CO2 could increase grain yield,straw biomass and plant height of two kind of rice to some different degree under 5 water management conditions.All of the two kinds of rice have a significant effect on the growth of rice with CO2、watermanagement and their interaction。It indicated that CO2 can promoted the growth of rice and mitigate the inhibition of drought on rice growth.(2)Drought at different growth stages can reduced the soil pH、Fe、Mn of iron plaque on root surface、but significantly increased the Cd of iron plaque.The increase of CO2 also reduced the pH of rhizosphere soil of two varieties to some different degrees.As a result the Cd accumulation of two kind of polished rice are increase.High CO2 can reduce the content of Cd in the polished rice of two varieties with varying degrees.The key parts for the enrichment of Cd in two kinds of rice are root and node.This result indicates further that root and node are two key parts of Cd enrichment in rice.(3)The 16 single and compounded treatment of red mud,sepiolite,palygorskite,humic acid can promote photosynthesis and increase grain yield by decreasing Cd toxicity and supplying nutrient elements for rice growth(4)Under three kinds of water management.single treatment and combined treatment of four kinds of passivating agents can reduce the accumulation of Cd in rice by increasing pH and decreasing the available Cd content of soil.Among them,1%sepiolite+1%red mud(T10)and 1%sepiolite+1%red mud treatment+1%humic(T14),1%palygorskite+1%red mud treatment+1%humic(T16)have good effect under three kinds of water conditions in reducing Cd condition and increases production at the same time.This result indicates that the application of immobilizing agent can ensure the safe production of rice under the condition of CO2 increase and seasonal drought.