殺草劑樂滅草在不同土壤中分解速率之比較

The Rate of Disappearance ofRonstar (Oxadiazon) in Different Soils

李國欽(Gwo-Chen Li) ； 翁愫慎(Sue-Sun Wong)

《中華民國雜草學會會刊》 1卷1期 (1980/06) Pp. 52-59

https://doi.org/10.6274/WSSROC-1980-001(1)-052

摘要

研究樂滅草Ronstar（oxadiazon; 2-tert-buty1-4-(2, 4-dichloro 5-isopropoxyphenyl) 1, 3, 4-oxadiazolin-5-one）在不同土壤中之分解速率發現，經過144天之後，不同土壤中分別殘留有73.1~96%之樂滅草。在含黏粒較多之土壤，樂滅草分解較快。在高壓殺菌後之土壤及未經高壓殺菌土壤中樂滅草之消失速率無顯著之差異，顯然樂滅草在環境中不易被微生物所分解。將Ronstar分別加入含飽和水，淹水30ml及淹水50ml之三種不同土壤之中，並曝露於254nm之紫外光下24小時。在含飽和水之處理下，樂滅草在三種不同土壤中，照光不照光者消失速率並無顯著差異，但以在含黏粒較多之土壤樂滅草分解較快。淹水狀況似有助於樂滅草之光分解。其在水土之分布中，偏土者消失較慢，偏水者消失較快。比較未照光及照光後樂滅草對稗草之毒性，以稗草之莖長及根長作比較，發現經照光後樂滅草之毒性顯著降低，顯然其分解產物具有較低之殺草能力。進一步研究樂滅草在日光下之分解速率及分解途徑之工作正在進行之中。

並列摘要

Studies on the rate of disappearance of Ronstar (Oxadiazon; 2-tert-butyl-4-(2, 4-dichloro 5-isopropoxyphenyl) 1, 3, 4-oxadiazolin-5-one) in three different soils revealed that after 144 days, 73.1 to 96% of initial ronstar still remained in the soil. The rate of disappearance of ronstar in the soil of high clay content was slightly faster than that of low clay content.There were no significant differences between the rate of disappearance of ronstar in the autoclaved and non-autoclaved soil, which indicated that microbial degradation played only a minor role in the degradation of ronstar in the soils.To study the photodegradation of ronstar in three different soils with saturated and flooded water by measuring the ronstar in the soil and water after exposure under UV light 254 nm for 24 hr, it was found that there were no significant differences the amounts of ronstar in the soils exposed to UV light and dark condition when the soils were saturated with water. But in the soils, flooded with water, the degradation occurred after 24 hr' exposure to the UV light. By comparing the amounts of ronstar in the soils, with higher clay content, it was found that exposure to the UV caused 33.8% and 21.3% disappearance of ronstar in soil and 1.7% to 69.6% disappearance in the surface water. In the soil with low clay content, exposure to the UV caused only to 0.9% disappearance in soil and 47.4% to 21.1% disappearance in the water. Degradation evidently occurred in the water and the rates of degradation was, higher in the system with high clay content than low clay content.Using the effect on shoot length and root length of barnyard grass as an indicator to study the toxicity of ronstar revealed that the herbicidal effects of ronstar was greatly decreased after exposure to the UV light.

並列關鍵字

Microbial and photo-degradation ； bioassay by barnyard grass