2种常用除草剂对1株稻田固氮念珠藻的毒性效应研究

Study on the Toxic Effects of 2 Commonly Used Herbicides on a Strain of Nitrogen Fixation Nostoc in Paddy Field

[目的]评价除草剂对固氮蓝藻的毒性。[方法]以稻田固氮蓝藻念珠藻FACHB85为供试藻种,研究除草剂莠去津和丁草胺的毒性效应。[结果]莠去津对FACHB85的毒性存在明显的剂量-效应关系,0.8 mg/L莠去津可明显抑制藻体生长(藻体比生长速率仅为对照的25%,且藻体断裂严重);在试验期(15 d)内莠去津对FACHB85的EC50值为0.035～0.080 mg/L,12 d后其EC50值达到稳定且高于前5 d的EC50值;随莠去津浓度增加,FACHB85的异形胞频率逐渐减小。在试验浓度(0～640 mg/L)范围内,丁草胺对FACHB85的生长基本无影响,且不同浓度丁草胺处理FACHB85的异形胞频率无显著差异。[结论]莠去津对FACHB85具有很强的毒性,而丁草胺对FACHB85的毒性较小。

[Objective] The purpose was to evaluate the toxicity of herbicides on nitrogen fixation cyanobacterium.[Method] With nitrogen fixation cyanobacterium Nostoc FACHB85 in paddy field as tested alga strain,the toxic effects of herbicides atrazine and butachlor was studied.[Result] The toxicity of atrazine on FACHB85 showed obvious dose-effect relationship.Atrazine of 0.8 mg/L could inhibit the growth of frond obviously,its specific growth rate was just 25% of that of CK and it had serious fragmentations.In the experimental period of 15 d,the EC50 of atrazine on FACHB85 was 0.035-0.080 mg/L,its EC50 became stable and higher than that of the former 5 d after 12 d;as the concentration of atrazine was increased,the heterocyst frequency of FACHB85 was reduced gradually.In the tested concentration scope of 0~640 mg/L,butachlor showed no influence on the growth of FACHB85 basically and the heterocyst frequencies of FACHB85 treated with butachlor of different concentration showed no obvious difference.[Conclusion] The toxicity of atrazine on FACHB85 was very intense and that of butachlor was less.