Phetkhajone Supawadee, Pichakum Aussanee, Songnuan Wisuwat
M.Sc. Programme in Plant Science, Faculty of Graduate Studies, Mahidol University, Nakhon Pathom 73170, Thailand.
Department of Plant Science, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
Plants (Basel). 2021 Apr 6;10(4):708. doi: 10.3390/plants10040708.
Metalaxyl is an effective approach to control infection in durian plantation. However, inappropriate metalaxyl usage may increase production cost, pathogen with fungicide resistance, and environmental toxicity. This study established and validated a simple and reproducible procedure to measure metalaxyl concentration in the durian leaf using HPLC. Linearity of the detection ranged from 1-100 µg/mL. The limits of detection (LOD) and quantification (LOQ) were 0.27 and 0.91 µg/mL, respectively. The extraction method gave recovery rates ranging from 88% to 103%. Durian seedlings were treated with 4 g/L metalaxyl either by foliar spray or soil drench. The highest metalaxyl accumulation in durian leaf was found between 6-24 h after treatment and persisted above its effective concentration at least 60 days after foliar application. The dissipation pattern fit to a first-order kinetics equation showed a half-life of 16.50 days. Soil drenching led to eight times higher metalaxyl concentrations in plants than foliar spraying and caused plant death within 15 days after application. These results suggest that foliar spraying of 4 g/L metalaxyl or soil drenching at a lower concentration every two months is sufficient in controlling infection in durian seedlings.
甲霜灵是控制榴莲种植园感染的一种有效方法。然而，不恰当使用甲霜灵可能会增加生产成本、产生具有杀菌剂抗性的病原体以及造成环境毒性。本研究建立并验证了一种使用高效液相色谱法（HPLC）测量榴莲叶片中甲霜灵浓度的简单且可重复的程序。检测的线性范围为1 - 100 µg/mL。检测限（LOD）和定量限（LOQ）分别为0.27和0.91 µg/mL。该提取方法的回收率在88%至103%之间。对榴莲幼苗通过叶面喷施或灌根的方式用4 g/L甲霜灵进行处理。在处理后6 - 24小时发现榴莲叶片中甲霜灵积累量最高，并且在叶面喷施后至少60天内其浓度持续高于有效浓度。符合一级动力学方程的消散模式显示半衰期为16.50天。灌根导致植物中甲霜灵浓度比叶面喷施高八倍，并在施药后15天内导致植物死亡。这些结果表明，每两个月叶面喷施4 g/L甲霜灵或较低浓度灌根足以控制榴莲幼苗的感染。
