| Arsenic（As）pollution in soil is a global environmental problem,which not only affects plant growth but also threatens human health and food security.Pteris vittata is the first reported As hyperaccumulator in the world,and also one of the few plants that have been successfully applied to remediation of soil As pollution.However,due to the low biomass of single treatment,low repair efficiency and long repair cycle of P.vittata,its large-scale application is limited.To this end,this study first studied the effects of different concentrations of As in soil on physiological characteristics and accumulation of As in P.vittata,and then enhanced the ability of accumulation of As in P.vittata by spraying ablative acid on leaf surface,applying biochar or hydrated lime in soil,and explored the effects of these three measures on the growth and accumulation of As in P.vittata.The main research results are as follows:（1）When the concentration of As in soil was 25～100 mg·kg-1,the P.vittata could grow normally with fresh green leaves.The As concentration of 50 mg·kg-1significantly increased the plant height,biomass,SPAD value and gas exchange parameters（Tr,Pn,Gs）of P.vittata（P<0.05）.With the increase of As concentration in soil,SOD and CAT activities and soluble sugar and soluble protein contents of P.vittata were significantly increased（P<0.05）,indicating that P.vittata adapted to the stress of As in the environment by regulating the activities of some antioxidant enzymes and the contents of osmotic regulatory substances in P.vittata.As content and accumulation amount in shoot of P.vittata gradually increased with the increase of As concentration（P<0.05）.Under the concentration of 100 mg·kg-1,the As content and accumulation amount were 1521.18 mg·kg-1and 17.68 mg·plant-1,respectively.（2）Leaf spraying with 15 mg·L-1 ABA could significantly increase transpiration rate,net photosynthetic rate,stomatal conductivity and SPAD value of P.vittata leaves（P<0.05）,while high concentration ABA treatment could inhibit photosynthesis of P.vittata leaves（P<0.05）.In addition,SOD and CAT activities were increased,MDA content was decreased（P<0.05）,and As content and accumulation in shoot of P.vittata were significantly increased（P<0.05）under 15mg·L-1 ABA treatment,which were increased by 27.57%and 51.62%compared with the control,respectively.These results indicated that appropriate application of ABA could improve the antioxidant capacity of P.vittata,reduce the level of membrane lipid peroxidation,promote photosynthesis and plant growth,increase As accumulation in shoot of P.vittata.（3）Application of biochar significantly increased soil p H,electrical conductivity,available potassium content,nitrate nitrogen content,organic matter content and available As content（P<0.05）,but significantly decreased soil ammonium nitrogen content（P<0.05）.The application of 8·tha-1 biochar significantly promoted the growth and accumulation of As in shoot of P.vittata（P<0.05）,and the fresh weight and As content in shoot of P.vittata increased by19.57%and 22.71%compared with the control,respectively.Therefore,applying appropriate amount of biochar in soil is an effective measure to improve soil physical and chemical properties and promote As accumulation in shoot of P.vittata.（4）The application of hydrated lime significantly increased soil p H,electrical conductivity,available phosphorus content and available As content（P<0.05）,but had no significant effect on the contents of ammonium nitrogen,nitrate nitrogen and available potassium in soil（P>0.05）.The plant height and fresh weight of the overground part of P.vittata increased first and then decreased with the increase of slaked lime application,and both reached the maximum value at the application of6·tha-1,which increased by 9.28%and 16.59%compared with the control,respectively.Meanwhile,the content and accumulation of As in shoot of P.vittata also reached the maximum under this treatment,and increased by 21.11%and38.3%compared with the control group,respectively.Therefore,applying appropriate amount of hydrated lime in soil is an effective measure to adjust the p H of acidic soil and increase As accumulation in shoot of P.vittata.In conclusion,the As accumulation ability of P.vittata is very strong,which can be used for the remediation of 25～100 mg·kg-1 As-contaminated soil.The As accumulation ability of P.vittata can be promoted by spraying ablative acid with appropriate concentration on the leaf surface and applying appropriate amount of biochar or hydrated lime in the soil,respectively.This study provides a new idea for promoting the As hyperaccumulator P.vittata and promoting its popularization and application in the restoration of As-polluted cultivated land. |
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