Effects Of Cadmium Stress On Cadmium Tolerance In Rice Under Drought Stress

As one of heavy metals,Cd is the source of pollution with serious hazards for the agriculture of extensive regions.It has remarkable toxic properties on the crops such as rice.The yield and quality of crops are usually influenced if Cd is excessive,causing serious harm to human health.In order to explore the technical approaches of enhancing the properties of rice for resisting Cd and lowering the accumulation of CD in rice,two rice varieties,Hanyou 73(drought-resistant variety)and Shenyou 9586(ordinary variety),were selected as materials to research the impacts of drought treatment and Cd stress environment on rice Cd absorption,accumulation and plant characters and analyze the relevance of inherent physiological functions between rice Cd resistance and accumulation properties and drought resisting and enduring properties by using potting water planting method and simulating arid environments via treating Peg6000(polyethylene glycol)of various concentrations.The main research results are as follows:(1)Cd accumulation in root systems can be remarkably reduced by drought treatment.With the increase of PEG6000 concentration,both the average Cd contents of the two varieties on the cell walls of 0-10 mm root segment and 10-20 root segment increased with different extents.The increase range of 0-10 mm root segment was larger.The Cd content on the cell walls of Hanyou 73 was 10.62-19.36mg/kg and that on the cell walls of Shenyou 9586 was 7.33-12.88mg/kg.The increase ranges reached 36.82%~82.30% and 26.74%~75.72% respectively,indicating that the differences were significant.(2)After removing border cells,the Cd accumulation on root cell walls increased with the increase of PEG6000 concentration and the increase range was larger,but the differences between 0-10 mm root segment and 10-20 root segment were not obvious.The Cd contents on the cell walls of 0-10 mm root segment were 11.63-21.41mg/kg(Hanyou 73)and 8.21-14.93mg/kg(Shenyou 9586)respectively.The increase ranges were 30.35%~84.09% and 25.21%~75.27% respectively,indicating that the differences were significant.(3)Drought treatment can have certain impacts on the tillering of rice with Cd pollution.The tiller number and percentage of earbearing tiller when the PEG6000 concentration was 3% were higher than the contrast and those when the concentrations were 6% and 9%.The maximum percentage of earbearing tiller reached 87% when the concentration was 3%,and the percentages of earbearing tiller were below 84% when the concentration was not 3%.However,the differences were not significant.(4)In Cd stress environment,the total dry weights of the overground parts for the plants in full heading stage and maturation stage displayed rising trend after being treated with PEG6000 of various concentrations.However,when the concentration reached 9%,the dry weight was lower,even lower than the contrast,and the differences were significant.