镉胁迫对小报春幼苗生长及生理特性的影响

该研究采用盆栽控制试验,测定不同浓度(0、5、50、100、150、200 mg/kg)土壤Cd胁迫下小报春幼苗生长及生理生化指标,以探究小报春(Primula forbesii Franch.)对重金属镉(Cd)污染的抗性和敏感性,为新型香花地被植物应用于Cd污染土壤提供理论依据。结果表明:(1)低浓度(5 mg/kg)Cd胁迫能促进小报春株高和根长的伸长,高浓度(≥150 mg/kg)Cd胁迫下株高、根长和生物量明显降低。(2)随Cd胁迫浓度增加,小报春幼苗叶片光合作用、叶绿素含量、SOD和CAT活性先上升后下降,而其超氧阴离子产生速率、过氧化氢、丙二醛含量、叶相对电导率和POD活性持续升高。(3)在Cd胁迫条件下,小报春体内K、Zn含量降低,叶和根中Ca、Mg含量显著增加,体内Cd含量明显升高,且根系Cd含量远远高于叶和叶柄。研究发现,小报春幼苗对Cd胁迫具有一定的耐性,低浓度(5 mg/kg)Cd胁迫对小报春生长影响较小,但高浓度(≥150 mg/kg)Cd胁迫对小报春产生明显的毒害作用,影响其正常生长;小报春可能通过增强体内抗氧化酶系统活性、增加叶和根中Ca、Mg含量和根系截留镉来减轻镉胁迫的伤害,提高自身耐受镉胁迫能力。

Effect of Cadmium Stress on the Growth and Physiological Characteristics of Primula forbesii Seedlings

In order to investigate the resistance and sensitivity of Primula forbesii Franch.to heavy metal cadmium(Cd)pollution,and to provide a theoretical and practical basis for the application as a new type of fragrant ground cover plant in Cd contaminated soil,we conducted a pot experiment to determine the growth and physiological indicators of P.forbesii seedlings under Cd stress in different concentrations(0,5,50,100,150,200 mg/kg)of soil.The results showed that:(1)low concentration(5 mg/kg)Cd stress could promote plant height and root length;however,the plant height,root length and biomass were significantly reduced under high concentration(≥150 mg/kg)Cd stress.(2)With the increase of Cd concentrations,leaf photosynthesis,chlorophyll content,SOD and CAT activities of P.forbesii seedlings increased firstly and then decreased,while its superoxide anion radical production rate,hydrogen peroxide content,malondialdehyde content,leaf relative conductivity and POD activity continued to increase.(3)Under Cd stress,the contents of K and Zn in P.forbesii decreased;the contents of Ca and Mg in leaves and roots increased significantly;the content of Cd increased obviously,and the Cd content in roots was much higher than that in leaves and petioles.This study shows that P.forbesii seedlings have a certain tolerance to Cd stress.Low concentration(5 mg/kg)Cd stress has little effect on the growth of P.forbesii,but high concentration(≥150 mg/kg)Cd stress has an obvious toxic effect on P.forbesii and affects its normal growth.However,P.forbesii may reduce the damage caused by cadmium stress and improve its tolerance by enhancing the activity of antioxidant enzyme system in vivo,with increasing the content of Ca and Mg in leaves and roots as well as the cadmium interception in roots.