除草剂百草枯对浮萍科不同植物的毒性效应比较

Toxic effects of herbicide paraquat on different species of Lemnaceae

为揭示除草剂对3种浮萍科植物的毒害作用,采用半数抑制浓度(IC50)和慢性值(ChV)分析并比较百草枯对其急性和慢性毒性效应。结果表明:处理96h后,紫萍、兰氏萍和浮萍叶状体的IC50值依次为17.37、6.16和4.75μg·L-1,百草枯对浮萍科不同植物的急性毒性作用存在明显差别(P<0.05);3种植物叶绿素含量均随百草枯浓度的升高而显著下降,处理4d后,两者呈显著负相关(P<0.05);紫萍的ChV为3.05μg·L-1,兰氏萍和浮萍的ChV均为0.96μg·L-1;根据叶状体指标,紫萍的ChV为10.780μg·L-1,浮萍的ChV仅为3.410μg·L-1,表明不论根据叶状体个数还是叶绿素含量,百草枯对浮萍的长期毒害效应均大于紫萍。因此,百草枯对3种浮萍科植物的毒害作用存在明显的分类学效应、浓度-剂量效应和时间滞后效应。

To explore the toxic effects of herbicides on different species of Lemnaceae, the medi- an inhibition concentration （IC50） and chronic value （ChV） of paraquat to Spirodela polyrhiza, Landoltia punctata, and Lemna minor were measured, with the acute and chronic toxic effects of paraquat on these three Lemnaceae species compared. After treated for 96 hours, the ICso value of paraquat to S. polyrhiza, L. punctata, and L. minor was 17.37, 6.16, and 4.75μg L-1 , respectively, and there existed significant differences among the acute toxicity （P〈0.05）. The chlorophyll content of the three species all decreased significantly with increasing paraquat con- centration, and after treated for four days, a significant negative correlation was observed between the chlorophyll content and paraquat concentration （P〈0.05）. The ChV of paraquat to S. polyrhiza was 3. 050 μg L-1 , and while that to both L. punctata and L. minor was 0. 964 μg L-1. However, in light of frond features, the ChV of paraquat to S. polyrhiza was 10. 780 μg L-1 , while that to L. minor was only 3. 410 μg L-1 , implying that the chronic toxic effect of pa- raquat to L. minor, whether from the viewpoint of frond features or chlorophyll content, was grea- ter than that to S. polyrhiza. Therefore, under the treatment of paraquat, the three species of Lemnaceae demonstrated obvious plant taxonomy effect, dose effect, and time lag effect.