不同生育期狼尾草属牧草对土壤镉胁迫的生理响应

Effects of Different Soil Cd Concentrations on Physiological Characteristics of Two Pennisetums at Different Growth Stages

试验采用盆栽的方法研究不同浓度(0,5,25,50,75,100mg·kg^(-1))重金属镉(Cd)胁迫对美洲狼尾草(Pennisetum amcrieanum)、杂交狼尾草(P.americanum×P.purpureum)3个生育期(幼苗期、分蘖期、抽穗期)生理特性影响。结果表明:随着Cd^(2+)浓度增加两种狼尾草叶片可溶性糖含量、细胞膜透性及脯氨酸含量呈递增趋势,叶绿素含量则逐渐降低。两种狼尾草在高浓度Cd^(2+)处理下(100mg·kg^(-1))与对照(0mg·kg^(-1))相比各指标均有显著性差异(P<0.05);随着生育期的延长,叶绿素含量逐渐升高;细胞膜透性递增幅度较大;而脯氨酸含量逐渐递减,其中杂交狼尾草的递减幅度较美洲狼尾草大;分蘖期Cd^(2+)浓度为75,100 mg·kg^(-1)时可溶性糖含量与其他Cd^(2+)浓度处理之间呈显著性差异。随着镉浓度的增加和生育期的延长,两种狼尾草的抗性反应更强烈,其中美洲狼尾草反应强于杂交狼尾草。

The physiological characteristics of P.americanumand P.americanum×P.purpureum under different Cadmium concentrations（0,5,25,50,75,100mg·kg^-1）were investigated by pot experiment at three growth stages.The results showed that levels of soluble sugar,proline,and membrane permeability in two kinds of Pennisetums increased with the increase of the concentration of Cd^2＋,while the levels of chlorophyll decreased gradually.The two kinds of Pennisetums treated with Cd^2＋ at high concentration（100mg·kg^-1）showed significant stress responses compared with the contrast（0mg·kg^-1）（P〈0.05）.As the growth stage went on,an increasing trend was observed for the levels of chlorophyll as well as a large increasment in cell membrane permeability.The levels of proline decreased gradually and the largest decrease was found in Hybrid pennisetum.The levels of soluble sugar treated with Cd100 and Cd75had a significant difference with other treatments during tillering stage（P〈0.05）.With the increase of Cd^2＋ concentration and the extension of growth stage,an obvious resistance response of two Pennisetums to Cd^2＋ was observed and Pearl millet had a better resistance response than Hybrid pennisetum.