多效唑15%可湿性粉剂在小白菜和土壤中残留动态研究

Residual Dynamics of 15% Paclobutrazol Wettable Powder on Cabbage and Soil

为了验证多效唑推荐施用浓度50mg·L-1的合理性,采用田间试验方法,施用不同浓度的多效唑50、250、500mg·L-1,研究在不同处理时间1、24、72h和7、14d,多效唑在小白菜以及土壤中的残留动态变化。结果表明:(1)多效唑在小白菜和土壤中的降解过程分别符合不同的一级动力学方程,当施用浓度为500mg·L-1时,其在小白菜叶片中的残留半衰期为57.76h,在土壤中的半衰期为60.27h;(2)按照推荐使用的施用浓度,采收时多效唑在小白菜和土壤中基本无残留,证明推荐施用浓度是合理的。

For identifying the rationality of recommended dosage 50 mg·L^-1 of paclobutrazol, a field trial was carried out to study the residual dynamics of 15% paclobutrazol wettable powder on cabbage and soil. The paclobutrazol of different concentrations 50、250、500 mg·L^-1 was used on the cabbage in its three-leaf period. By using Gas chromatography techniques, the residual dynamics were research on cabbage and soil, under the different exposure of 1,24,72,168,336 h.The results were as follows：（1）The degradation of paclobutrazol in cabbage and soil could be described with different one class dynamics equation. When 500 mg·L^-1 of paclobutrazol was applied, the half life of cabbage and soil was 57.76 h and 60.27 h.（2）When applied according to the recommended dosage, There was no residues of paclobutrazol in the cabbage can be checked in 168h.The average growth period of cabbage was 30 d. Using the one class dynamics equatio, the residuce of paclobutrazol was extremely lower than the lowest limit of detection when the cabbage was mature. So it testified that using this recommended dosage was reasonable.