The pollution monitoring index system of wheat at different growth stages under the stress of Cd,Cr and Pb
小麦不同生育时期Cd、Cr、Pb污染监测指标体系

With wheat as test material,a series of experiments including toxic germination tests,hydroponic and soil column culture were carried out to study the pollution monitoring system of toxic heavy metals in wheat at different growth stages.EC_(50)'s were used to order toxicity of the heavy metals.The results indicated that:①The decrease in root elongation rate might be an effective bio-marker to estimate heavy metal pollution.The 7d EC_(50) of Cd,Cr and Pb on the root elongation were 1.39retool·L~(-1),0.20mmol·L~(-1) and 2.75mmool·L~(-1),so their toxicity ranked as Cr＞Cd＞Pb.Relations between the inhibition to each traits and heavy metals concentrations were well fitted into math models of hyperbola equation y=x/(α+x/100)or exponential curve y=a(1-exp(-bx)).②Heavy metal stress to wheat seedlings was most obvious in leaf area(LA)and top weight(TW),so LA and TW may act as sensitive indices for pollution monitoring at seedling stage.All traits except for root weight were affected by heavy metal in that order of Cr＞Cd＞Pb.Relations between inhibition rates to wheat agronomic traits and heavy metal concentrations were better showed by linear equation,hyperbola equation or exponential curve.③Toxicity of soil heavy metals in terms of grain yield decrease ranked as Cd＞Cr＞Pb.Interactions between any double stresses of heavy metals on grain yield followed as CdCr＞CdPb＞CrPb.The ear number Was the first choice to be used for pollution monitoring at mature stage under multiple stresses.Our obtained results will provide theoretical basis for pollution monitoring and comprehensive control in farmland.