裸燕麦对重金属镉(Cd)胁迫的生理生态响应及Cd累积特性

Physiological-Ecological Responses of Naked Oat to Cadmium(Cd) Stress and Cd Accumulation

重金属镉(Cd)污染已成为全球面临的环境问题之一。为明确Cd胁迫对裸燕麦种子萌发、光合作用、活性氧代谢、Cd累积特性和植株生长的影响,以裸燕麦定莜6号为材料,用不同浓度的Cd^2+处理种子并进行盆栽土培试验。结果表明,5~100mg·L^-1Cd^2+处理对裸燕麦种子的发芽率和发芽指数没有影响,对活力指数、胚根长和幼苗干重的抑制程度随C^d2+浓度增加而增强。在5~50mg·kg-1Cd^2+胁迫下,随着Cd^2+浓度上升,抽穗期裸燕麦叶片的光合色素含量、净光合速率、气孔导度和蒸腾速率下降速率增大,胞间CO2浓度、O2^-·、H2O2和丙二醛含量提高,超氧化物歧化酶和过氧化氢酶活性先升后降,过氧化物酶活性呈升-降-升趋势,抗坏血酸过氧化物酶活性和抗坏血酸含量逐渐下降,谷胱甘肽含量提高。抽穗期裸燕麦根系和地上部Cd含量和Cd累积量随Cd^2+处理浓度增加而提高,根系和地上部对Cd的富集系数及转运系数依次下降。成熟期裸燕麦的株高、产量和产量构成因子随Cd处理浓度上升而下降。总之,Cd胁迫抑制了裸燕麦壮苗形成;使植株Cd积累增加;诱导活性氧代谢紊乱和光合作用下降,使植株生长受抑和产量降低。

Heavy metal cadmium(Cd) pollution has become one of the serious environmental issues in the world.In order to clarify the physiological responses of naked oat( Avena nuda ) to Cd stress and accumulation characteristics of Cd,in this study,we took Dingyou 6,a naked oat variety,as the material.The seeds were treated with different concentrations of Cd^2+(0,5,10,25,50 and 100 mg·L^-1 ),and soil pot experiment with five different Cd concentrations(0,5,10,25 and 50 mg·kg ^-1 in the soil) was conducted to study the effects of Cd stress on the seed germination,photosynthesis,reactive oxygen metabolism,Cd accumulation and plant growth of naked oat.The results showed that Cd stress had no effect on germination rate and germination index of naked oat seeds,but the inhibition on vigor index,radicle length and seedling dry weight were enhanced with the increase of Cd^2+ concentration.With increase of soil Cd^2+ concentration,photosynthetic pigment content,net photosynthetic rate,stomatal conductance and transpiration rate were all decreased,but intercellular CO2 concentration,O2^-·,H2O2 and malondialdehyde contents were increased,and superoxide dismutase and catalase activities were increased and then decreased.Peroxidase activity showed a trend of rising,falling and rising,ascorbate peroxidase activity and ascorbate content decreased gradually,while glutathione content increased continuously in leaves of naked oat at heading stage.Cd concentration and accumulations in root and shoot of naked oat at heading stage was increased gradually with the soil Cd concentration increasing,while accumulative factor and translocation factor were decreased.In addition,the plant height,yield and yield components of naked oat at the mature period were decreased significantly with increase of soil Cd concentration.These results revealed that Cd stress inhibits the formation of healthy seedlings and the accumulation of Cd in plants,induces the disturbance of reactive oxygen metabolism and the reduction of photosynthesis in leaves,as well as the growth inhibition and yield reduction of naked oat.