除草剂药液体系在不同水稻季别温度下的稳定性

    Stability of herbicide solution systems under temperature variations across different rice-growing seasons

    • 摘要: 为探索稻田除草剂药液因天气变化、作业调度冲突等需临时存放的实际问题,本研究明确了6种常用稻田除草剂300 g/L丙草胺乳油 (EC)、60%丁草胺EC、100 g/L氰氟草酯EC、3%氯氟吡啶酯EC、10%噁唑酰草胺·氰氟草酯EC和38% 2甲4氯·灭草松水剂 (AS)药液在不同水稻季别温度下的稳定性。按稻田除草剂常规喷液量450 L/hm2标准,采用超纯水配制药液,分别模拟早、中、晚稻除草剂施用时期的昼/夜温度(早稻22 ℃/15 ℃和25 ℃/18 ℃,中稻29 ℃/22 ℃和31 ℃/24 ℃,晚稻33 ℃/26 ℃和36 ℃/27 ℃)于黑暗条件下储存24 h,评估其物理稳定性、化学稳定性及田间生物活性稳定性。结果显示:物理稳定性方面,300 g/L丙草胺EC和100 g/L氰氟草酯EC药液储存后出现了分层现象,且早稻温度下分层出现时间较中、晚稻晚,但达到最大分层体积的时间更早;其余4种药剂则均未出现分层。化学稳定性方面,在配制后24 h内,所有药液有效成分质量浓度均无显著性变化(P > 0.05)。生物活性稳定性方面,药液配制后24 h施用与现用现配效果相当。其中,10%噁唑酰草胺·氰氟草酯EC 2250 mL/hm2剂量下处理后15 d 和30 d,对稗草的防效均在95%以上;38% 2甲4氯·灭草松AS 1500 mL/hm2剂量下处理后15 d和30 d,对阔叶杂草及莎草科杂草的防效均为100%,且对水稻安全。研究表明,在常规喷液量下,稻田除草剂药液配制后24 h内化学稳定性良好,且不影响其生物活性稳定性。

       

      Abstract: To explore the temporary storage of paddy herbicide solutions due to weather changes, operational scheduling conflicts, and other factors, the stability of six herbicides for paddy fields, including pretilachlor 300 g/L EC, butachlor 60% EC, cyhalofop-butyl 100 g/L EC, florpyrauxifen-benzyl 3% EC, metamifop + cyhalofop-butyl 10% EC, and MCPA + bentazone 38% AS was clarified under temperature variations among different rice-growing seasons. Herbicide solutions were prepared in ultrapure water corresponding to a field spray volume of 450 L/hm2 and stored in dark for 24 h. The storage conditions simulated diurnal temperature fluctuations during early- (22/15 °C, 25/18 °C), middle- (29/22 °C, 31/24 °C), and late-season (33/26 °C, 36/27 °C) rice application periods. Then, their physical, chemical, and bioactivity stability were evaluated. Physical stability results showed phase separation in solutions of pretilachlor 300 g/L EC and cyhalofop-butyl 100 g/L EC. Under early-season rice temperature regimes, phase separation initiated later but progressed to its maximum volume more rapidly compared to middle- and late-season conditions. No phase separation was observed in the other four herbicide formulations. Regarding to chemical stability, there were no significant differences (P > 0.05) in the mass concentrations of active ingredients in all solutions within 24 h after preparation. Bioactivity of solutions stored for 24 h was comparable to that of immediate application after preparation. For instance, metamifop + cyhalofop-butyl 10% EC, applied at the dosage of 2250 mL/hm2, provided over 95% control of barnyardgrass at 15 and 30 days after application. MCPA + bentazone 38% AS applied at 1500 mL/hm2 achieved 100% control of broadleaf weeds and sedges at 15 and 30 days after application, with no observed phytotoxicity to rice. These results indicate that the tested paddy herbicide solutions exhibit satisfactory chemical stability within 24 h after preparation under conventional spray volumes, without compromising the stability of their bioactivity.

       

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