Physiological Toxicity Of Chemical Pollutants To Plants Were Alleviated By Environmental Materials

With the advancement of science and technology,the environmental pollution caused by chemical pollutants is becoming more and more serious.Environmental materials are known to have a lowest environment load and superior performance.Moreover,Environmental materials can alleviate chemical substance-induced environmental pollution.Therefore,we first investigated the physiological toxicity of cadmium?Cd?and copper?Cu?stress to Astragalus membranaceus seedlings and alleviative effects of attapulgite clay in growth substrate on Cd and Cu stress;and then,we investigated physiological responses of Oryza sativa L.seedings to magnetic?Fe₃O₄?nanoparticles?MNPs-Fe₃O₄?and their function in reducing the physiological toxicity of nitrophenol?NP?;finally,we investigated the physiological responses of Oryza sativa L.seedlings to different outer diameter multi-walled carbon nanotubes?MWCNTs?and alleviative effects of MWCNTs on physiological toxicity of trichlorobenzene?TCB?.The main findings were as follows:?1?The Cd content in roots and leaves,root hydrogen peroxide content,malondialdehyde content,plasma membrane permeability,and the damage degree of root apical membrane of Astragalus membranaceus seedlings were increased,while the seedling growth,leaf PS II photochemical efficiency and chlorophyll content were decreased under Cd stress(1 mmol·L^-1,5 mmol·L^-1,10 mmol·L^-1,15 mmol·L^-1).Simultaneously,the activities of SOD?superoxide dismutase?,APX?ascorbate peroxidase?,POD?peroxidase?,CAT?catalase?,soluble protein content,and soluble sugar content of roots were increased first but then decreased with the increasing Cd concentrations.Under the condition without Cd stress,the attapulgite clay presence in the growth medium did not induced a significantly effect on above physiological indexes were measured.Under Cd stress,the presence of attapulgite clay in the growth substrate significantly alleviated the Cd-induced adverse effects on seedlings.And,the alleviative effects of attapulgite clay on Cd stress to Astragalus membranaceus roots were more obvious with the increase of Cd stress time.These results suggest that attapulgite clay could be used as a beneficial component for the seedling cultivation of Astragalus membranaceus,particularly when excess cadmium ion emerges in growth medium.?2?Cu(2 mmol·L^-1,8 mmol·L^-1,15 mmol·L^-1,20 mmol·L^-1)stress caused the Cu content in roots and leaves,root hydrogen peroxide content,SOD activity,malondialdehyde content and the damage degree of root apical membrane of Astragalus membranaceus seedlings were increased,whereas the seedling growth,root APX activity,leaf PS II photochemical efficiency and chlorophyll content were decreased.Simultaneously,the root POD activity,CAT activity,soluble protein and soluble sugar content were increased first but then decreased with the increasing Cu concentration.Under the condition of non-stressed conditions,the addition of attapulgite clay into the growth substrate did not cause an adverse effect on seedlings.More importantly,the addition of attapulgite clay into the growth substrate under Cu stress significantly slowed down the Cu-stress-induced negative effects on seedlings.And,the alleviative effects of attapulgite clay on copper stress to Astragalus membranaceus roots were more obvious with the increase of Cu stress time.These results show that the addition of attapulgite clay has a protective on Astragalus membranaceus seedlings under Cu-stressed condition.?3?The results showed that treatment with MNPs-Fe₃O₄(100 mg·L^-1,500 mg·L^-1,1000 mg·L^-1,2000 mg·L^-1)enhanced the growth,the content of root soluble sugar,PS II photochemistry activity,and chlorophyll content of Oryza sativa L.seedlings,while the production of reactive oxygen species[ROS,including O₂^·-and H₂O₂]and the activities of antioxidant enzymes?SOD,POD,CAT and APX?were also increased by MNPs-Fe₃O₄treatment.Np(70?mol·L^-1,140?mol·L^-1,280?mol·L^-1,560?mol·L^-1),when emerged in growth medium,decreased the growth,PS II photochemistry,and chlorophyll content of Oryza sativa L.seedlings at a dose-depended manner,and NP also changed the content of root soluble sugar,metabolism of ROS production and antioxidant enzyme activity.When NP(280?mol·L^-1)emerged in growth medium?5 h?,MNPs-Fe₃O₄ was added to absorb NP and then the MNPs-Fe₃O₄ was separated with a magnet.Such treatment effectively alleviated the physiological stresses induced by NP.These results suggest that MNPs-Fe₃O₄ at moderate concentration can be advantageous for the Oryza sativa L.seedlings and has potential to relieve the NP-induced physiological stresses.?4?MWCNTs with three different outer-diameter(<8nm,20-30 nm,and>50 nm,1g·L^-1,respectively)were applied to the roots of Oryza sativa L.seedlings grown for 10d under hydroponic condition.Treatment with MWCNTs with outer-diameter<8 nm or at 20-30 nm reduced the seedling growth,biomass,and root soluble protein content,soluble sugar content,SOD,POD and APX activity,leaf PS II photochemistry activity and chlorophyll content,While the root O₂^·-production rate and CAT activity were increased.However,MWCNTs with outer-diameter>50 nm effectively enhanced these physiological parameters of Oryza sativa L.seedlings.We further investigated the alleviative effects of MWCNTs with outer-diameter>50 nm on the toxicity of TCB to Oryza sativa L.seedlings.without TCB stress,the MWCNTs presented in medium increased the root soluble sugar content,leaf PS II photochemistry activity and chlorophyll content.In comparison with TCB stress,the MWCNTs presented in medium significantly alleviated the TCB-induce negative effects on Oryza sativa L.seedings growth,root soluble protein content,soluble sugar content,ROS metabolism balance and antioxidant enzyme activity,and leaf PS II photochemistry activity and chlorophyll content.These results suggest that MWCNTs at moderate outer-diameter can be used as an advantageous additive during the growth of Oryza sativa L.seedlings and can protect the Oryza sativa L.seedlings from the toxicity of TCB.