Effects Of PH And Flooding Conditions On Cadmium Uptake By Rice In A System Of Intercropping System Between Rice And Southeast Sedum

Soil heavy metal pollution poses increasingly serious threats to the agricultural environment.Farmland environmental pollution and the quality and safety of agricultural products are currently the focus of public and academia.pH and moisture conditions affect the adsorption-desorption,oxidation-reduction and other processes of heavy metal ions in soils,which may change their bioavailability and environmental risks.Therefore,adjusting the pH and moisture conditions during crop growth will have an impact on the environmental behavior of pollutants and the absorption of crops.Phytoremediation of heavy metal pollution is one of the more effective and safe methods for repairing heavy metals.This paper discusses the effects of rice and hyper-enriched plants on the restoration of heavy metal cadmium in the soil of the southeastern intercropping system.Using rice as the experimental material,pot experiments were conducted to study the effects of pH and moisture conditions on rice Cd uptake in rice and remediation intercropping systems.The effects of Cd on the transformation and migration in soil-rice system were analyzed,and the effects of pH and moisture conditions on rice growth,physiological index and yield were observed.The main findings are as follows:1.Pot experiment 1 studied the effect of pH on rice growth and cadmium uptake.The results showed that the biomass,tiller number and plant height of rice all showed an increasing trend with the increase of pH in soil polluted by cadmium,and the accumulation of heavy metals in various tissues and organs of rice decreased.When the pH was 8,the biomass,tiller number and plant height of rice weresignificantly higher than that of the treatment group with pH 4.5,and the ability of each part of rice to accumulate heavy metal cadmium was weaker than the pH 4.5treatment group.Under the same pH conditions,the ability of rice to absorb heavy metal cadmium in rice and southeast intercropping system was slightly weaker than that of rice.At a pH of 4.5,the Cd content of monocropping rice was 1.37 mg/kg,while that of intercropping rice was 1.25 mg/kg.When the pH was 8,the Cd content of the monoculture rice was 0.31 mg/kg,while the Cd content of the intercropping rice was 0.28 mg/kg.It is speculated that in the system of intercropping between rice and the southeastern landscape,the southeast sedum weakens the absorption of heavy metal cadmium by rice,which helps to reduce cadmium contamination in rice.2.Pot experiment 2 investigated the effects of water conditions on rice growth and cadmium uptake in paddy rice and southeastern intercropping systems under cadmium-contaminated soil.The results showed that under droughty water conditions,the plant height and biomass of rice were significantly lower than other treatments.The change of water conditions led to a corresponding change in the amount of cadmium absorbed by rice under monocropping and intercropping systems.When the dry-wet alternation(water flood height was 0-3cm),the Cd content in the roots of monocropping rice was 37.06mg/kg,but the Cd content in rice roots was decreased in the rice and the southeastern Sedum intercropping group.When the water was flooded for a long time(keeping the flood height >5cm),the Cd content in the roots of monocropping rice was 3.28mg/kg,but the Cd content in the roots of the rice and the rice seedlings in the southeastern Jingtian also decreased.With the increase of ridge height in the intercropping system between rice and the southeastern landscape,the Cd value in the ditch rice soil also decreased.The pot experiment 3 mainly studied the changes of cadmium in the soil of rice growth and soil under the influence of four different atmospheric depositions.The rice biomass and plant height under acid rain precipitation(S),oxidative sedimentation(H)and simulated acid rain and oxidative sedimentation(M)were higher than that of normal rainwater sedimentation treatment.However,the biomassand plant height of rice when the flooding height was 0 to 3 cm was less than the rice biomass and plant height when the flooding height was more than 3 cm.Acid rain and oxidative sedimentation have a certain effect on the form of heavy metal cadmium.The first is exchangeable cadmium,artificial rainwater> oxidative sedimentation>simulated acid rain and oxidative sedimentation> simulated acid rain sedimentation;reducible cadmium,simulated acid rain and oxidative sedimentation> oxidative sedimentation> simulated acid rain sedimentation> artificial rainwater;exchangeable Cadmium,when flooding height is 0~3cm,simulated acid rain sedimentation>simulated acid rain and oxidative sedimentation> oxidative sedimentation> artificial rainwater,and when flooding height is >3cm,oxidative sedimentation> artificial rain> simulated acid rain Settlement> simulated acid rain and oxidative sedimentation;residual cadmium,simulated acid rain sedimentation> simulated acid rain and oxidative sedimentation> oxidative sedimentation> artificial rainwater.In summary,the present study shows that pH and moisture conditions have a certain influence on rice growth and cadmium uptake in rice and intercropping systems.With the increase of pH,the ability of rice to repair the heavy metal cadmium pollution with the southeastern landscape will be enhanced,and with the increase of the rice and southeast Jingtian ridge height,the soil Cd value also decreased accordingly.Through this experiment,it was found that the optimum pH was weakly alkaline,and rice and the southeastern landscape could recover the polluted soil most efficiently at this time.We hope that we can use this experiment to find out the best pH and moisture values for the restoration of heavy metals between rice and the southeastern landscape,which has practical significance in the cadmium pollution and phytoremediation in rice fields.