生测法测定甲草胺在土壤中的残留量

A BIOASSAY METHOD FOR THE DETERMINING THE RESIDUE OF ALACHLOR IN SOIL

根据甲草胺对敏感植物的幼根或幼茎有抑制作用的原理,采用培养皿土培方法,通过测量发芽种子的根、茎长度来测定甲草胺在土壤中的残留量。实验室筛选试验表明,豌豆、黄瓜幼根及燕麦、小麦幼茎是测定甲草胺在土壤中残留量的敏感试材。豌豆及黄瓜的根部对甲草胺的敏感浓度线性范围较宽,为0.1—8.0微克/克土,IC_(50)(在草甸黑土中抑制根长50％所需要的甲草胺浓度)为3.23ppm±0.20及2.3ppm±0.16;燕麦及小麦茎部的敏感范围较窄,为0.5—5.0微克/克土,IC_(50)为1.3 ppm±0.10及2.8 ppm±0.15。用豌豆根生测法测定甲草胺在田间土壤中的消解动态表明,甲草胺在花生田草甸黑土中降解较快,半衰期为3天左右,其结果与气相色谱法接近。

Bassed on the inhibition of primary root and shoot growth in susceptible species by alachlor,measurement of the root or shoot lengths of pre—germinated seed grown in the soil contained in petridish was used to assay soil residue of alachlor.Laboratory screening tests proved that both the roots ofpea and cucumber and shoots of oats and wheat were susceptible species for the bioassay of alachlor.The root lengths of pea and cucumber showed a wide susceptible range response to soil concentrationof alachlor between 0.1—8.0μgg^(-1) soil,IC_(50) (the conc,of alachlor required to yield a50%reduction in root growth in the Meadow phaeozem soil) was 3.23 ppm± 0.20 and 2.3 ppm±0.16;the shoot lengths of oats and wheat showed a narrow susceptible range response to soil concen-tration of alachlor between 0.5—5.0 μgg^(-1) soil IC_(50) was 1.3 ppm ±0.10 and 2.8 ppm ±0.15.Field degradation studies with pea root bioassay showed that alachlor was degraded quickly onmeadow phaeozem soil of peanut field,the half life was about 3 days,it was same with the results ofGC method.