Effects of Aluminum Stress on Seed Germination and Physiological Characteristics of Root Tips in Taiwania flousiana
In order to explore effects of aluminum stress on seed germination and physiological characteristics of root tips in Taiwania flousiana,seed germination and root tip experiments were carried out under different aluminum concentrations.In seed germination experiment,11 treatments were set up including two 0 mg/L alu-minum treatments with pH 7.0 and 4.0 respectively and 9 treatments with different aluminum concentrations(20,50,100,500,1 000,1 500,2 500,3 000 and 3 500 mg/L,pH 4.0),and germination ability of seeds,alumi-num content of root tips and root vitality were measured.In root tip experiment,there were 7 treatments with dif-ferent aluminum concentrations(0,50,100,500,1 000,2 000 and 4 000 mg/L,pH 4.0)for germinated seeds.Contents of aluminum and malondialdehyde(MDA)in tip roots,root vitality and activities of superoxide dis-mutase(SOD),peroxidase(POD),polyphenol oxidase(PPO),catalase(CAT)and ascorbate peroxidase(APX)in tip roots were measured.Results showed that aluminum concentrations below 50 mg/L could promote germina-tion rate and germination index of T.flousiana seeds.With increase of aluminum concentration,germination rate,germination potential,radicle lengths at 15 and 25 day,germination index,vitality index and average fresh weight increased firstly and then decreased.Aluminum concentration of 1 500 mg/L was semi-lethal concentra-tion of T.flousiana seeds,and aluminum concentration of 3 500 mg/L was lethal concentration of T.flousiana seeds.With increase of aluminum concentration,MDA content in radicle root tips decreased firstly and then in-creased.SOD activity decreased.Activities of POD and PPO showed increase trends.CAT activity increased firstly and then decreased.APX activity decreased firstly,then increased and decreased again.With increase of aluminum concentration,content of aluminum in radicle root tips increased,and root vitality decreased.During seed germination and growth,T.flousiana had strong aluminum tolerance,and could germinate and grow in soils with aluminum concentrations less than 1 500 mg/L.After being stressed by aluminum,seeds of T.flousi-ana increased resistance by adjusting antioxidant activities.
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