不同质地土壤中Cd胁迫对灌浆期小麦根际环境的影响

通过网室盆栽试验,研究砂土、壤土、粘土3种质地土壤上不同w(Cd)胁迫对灌浆期小麦根际环境的影响,测定小麦根的形态生理指标(根长、根系活力)、根际土壤酶活性(土壤脲酶、土壤蔗糖酶)、土壤w(Cd)及其有效态w(Cd)、小麦根和籽粒w(Cd)。结果表明,当w(Cd)≤40mg/kg时,小麦根长、根系活力和土壤酶活性均高于对照;当w(Cd)≥60mg/kg时,小麦根系生长受到抑制,土壤酶活性均明显下降。对于不同质地土壤,壤土上小麦根长、根系活力及土壤酶活性较砂土和粘土高;对w(Cd)来说,土壤w(Cd)依次为壤土>粘土>砂土,土壤有效态w(Cd)为砂土>粘土>壤土,小麦根w(Cd)为砂土>壤土>粘土,籽粒w(Cd)为砂土>壤土>粘土。说明壤土和粘土对Cd的吸附性较高,土壤中Cd的可利用性较差,因而Cd从土壤迁移到植株中较少;而砂土对Cd的吸附能力最差,进入小麦植株中也最多。因此,在壤土和粘土上种植小麦可在一定程度上减轻Cd的胁迫作用,能有效缓解Cd对小麦的毒害,而在砂土上种植小麦,Cd胁迫作用则表现的较为突出。

Effect of Cadmium Stress on Wheat Rhizosphere Environment in Three Soil Textures during Filling Stage

The soil texture is one of the most important factors impacting on the rhizosphere environment of crops and heavy metals migration in field.With different concentrations of cadmium stress,the rhizosphere environment of wheat during filling stage was studied in pot experiment in screen house in order to find the difference of three soil textures.Many morphological and physiological indexes,including wheat root length,wheat root activity,soil urease activity,soil sucras activity,cadmium content in soil and wheat,were determined.The results showed that,when concentration of cadmium was lower than 40 mg/kg,wheat root length,wheat root activity,soil urease activity and soil sucras activity were all bigger than the control(0 mg/kg cadmium),but activities of different soil enzymes were inhibited when the concentration of cadmium was more than 60 mg/kg.Considering the soil texture,the growth of wheat root and the enzyme activities of soil in loam were better than in sandy soil and clay soil.Besides,total cadmium in three textures of soil was listed as loam>clay>sandy soil,available cadmium as sandy soil>clay>loam,cadmium in wheat root as sandy soil>loam>clay,and cadmium in wheat grain as sandy soil>loam>clay,which indicated that clay and loam had stronger adsorption ability to cadmium than sandy soil.And so,cadmium stress to wheat plants was more alleviated in clay and loam for less transport of cadmium than in sandy soil.In conclusion,cadmium pollution for grown wheat was less in loam and clay than in sandy soil.