镉胁迫对两种蔊菜生长的影响及其在植物体内的积累和转运特性

Effects of Cadmium Stress on Growth of Two Species of Rorippa and the Characteristics of Accumulation and Translocation to Cd in Plants

为探究植物对镉胁迫的响应机制和富集特性,以欧亚蔊菜(Rorippa sylvestris)和两栖蔊菜(Rorippa amphilia)为试验材料,采用盆栽方式,镉处理浓度分别为0,50,100,200,400mg·kg^-1,通过测定株高、生物量、光合参数以及植物体内镉的含量等指标,研究镉胁迫对两种蔊菜生长的影响,分析镉的吸收和转运特性,探讨两种蔊菜对镉的耐受性和富集能力。结果表明:当镉浓度为50mg·kg^-1时,两种蔊菜生长受到的影响较小;当镉浓度高于50mg·kg^-1时,两种蔊菜生长受到抑制。随着镉浓度增加,叶绿素含量逐渐减少,最大净光合速率Pn逐渐下降,最大光合效率(Fv/Fm)逐渐降低,表现出光抑制;光合电子传递速率(ETR)逐渐降低,而非光化学淬灭系数(NPQ)逐渐升高,说明叶片的光合系统受到破坏。随着镉处理浓度增加,两种蔊菜的根、茎、叶中镉含量逐渐增大,各处理间差异显著,除对照外,各处理地上部分镉含量都超过100mg·kg^-1;地上富集系数和地下富集系数呈现增加的趋势,且均大于1.0;欧亚蔊菜的转运系数都大于1.0,各处理间差异不显著;两栖蔊菜在镉浓度为50mg·kg^-1时,地上转运系数大于1.0;欧亚蔊菜的转运系数均高于两栖蔊菜。该研究结果表明两种蔊菜对镉具有较强的耐性,且欧亚蔊菜的富集能力强于两栖蔊菜,二者均为镉的超富集植物。

In order to explore the response mechanism and enrichment characteristics of plants to cadmium stress,pot experiments were conducted to investigate the effect of different concentrations cadmium(0,50,100,200,400 mg·kg^-1)on the growing development of Rorippa sylvestris and Rorippa amphilia by measuring plant height,biomass,photosynthetic parameters and cadmium content in plants,to analyze absorption and transport properties of cadmium,and to discuss their abilities of enrichment and tolerance of cadmium.The results showed when the concentration of cadmium was 50 mg·kg^-1,the growth of 2 species of Rorippa was influenced a little and inhibited significantly while the concentrations of application Cd were morethan50 mg·kg^-1.With the increase of cadmium concentration,the chlorophyll content and Fv/Fm gradually decreased,showing the phenomenon of photoinhibition,and ETR decreased and NPQ increased,indicating that the photosynthetic apparatus of the leaves was damaged;cadmium content in roots,stems and leaves increased gradually,and there was significant difference between the treatments.Except for CK,the cadmium content was more than 100 mg·kg^-1;the bioconcentration factors(BCFs)in foots and shoots increased and were greater than 1.0.The translocation factor(TF)of Rorippa sylvestris was greater than 1,the differences between treatments were not significant,and the IF in shoots of Rorippa amphilia was more than 1.0 when the concentrations of application Cd were 50 mg·kg^-1,and the TFs in shoots Rorippa sylvestris were more than those of Rorippa amphilia.The research result indicated that Rorippa sylvestris and Rorippa amphilia had strong tolerance to cadmium,and the Cd concentration ability of the former was stronger than the later,and both of them were cadmium hyperaccumulators.