不同类型界面液滴蒸发特性与农药利用效果研究进展

Reasearch advances of droplet evaporation on different interfaces and the efficiency of pesticide utilization

农药液滴在靶标植物叶片表面的蒸发是农药对靶沉积后的重要过程,也是影响农药利用率和对有害生物防控效果的关键。液滴蒸发过程存在多种模式:接触半径恒定的CCR(Constant contact radius)模式、接触角恒定的CCA(Constant contact angle)模式以及混合模式(Mixed mode)等,不同蒸发模式下液滴的形态变化及蒸发时间均有一定差异。文章综述了液滴在光滑固体界面、人工修饰后具有不同微观结构的粗糙界面以及不同植物界面上的蒸发动力学研究进展。现有研究表明:在光滑固体界面上,液滴蒸发速率随蒸发时间呈线性变化趋势;在不同微观结构修饰后的粗糙界面上,液滴蒸发速率和蒸发模式受固体表面特性的影响;在不同植物界面上,叶片表面的微观结构与组分特性是影响农药液滴在叶片上沉积、持留、铺展及药液渗透过程的重要因素,富含蜡质层以及微纳米结构的叶片,一般不易被农药液滴润湿,液滴铺展面积小,蒸发相对较慢。通过加深对靶标植物叶片表面农药液滴蒸发行为的认知,可以根据有害生物为害特性与有效防控剂量需求,合理调控农药液滴在靶标植物叶面的蒸发时间,同时可为指导农药制剂中表面活性剂的合理应用及提高农药有效利用率提供理论依据。

The evaporation of droplet on crop leaf surface is a key progress in the pesticide spraying application when the droplet deposited on target crops. It also has an effect on the utilization rate of pesticide and the control efficiency. Studies demonstrated that there are many evaporation modes during the whole evaporation period such as CCR（Constant contact radius） mode, CCA（Constant contact angle） mode, Mixed mode and so on. Besides, the evaporation mode has an influence on both the profile of the droplet and the whole evaporation time. To understand the evaporation kinetics of pesticide droplets on the target crop, the evaporation dynamics of droplets on the smooth solid interface, artificial modified interface with different microstructure and on different plants surfaces was reviewed. Recent literature revealed that the evaporation rate of droplet on the smooth solid surface has a linear trend with the evaporation time. On the artificial modified interface, the evaporation rate and the evaporation mode are affected by the solid morphology. On different leaf surfaces, wettability is an important factor in the process of the droplet depositing, withholding, spreading and penetrating on leaf surfaces. In general,the droplet spreading area and the evaporation rate are proportion to the wettability of the leaf surfaces.With better understanding of the evaporation dynamics of the pesticide droplet on target crop leaves, the evaporation time on crop leaf surfaces can be regulated through the damage characteristics of pests and effective prevention of dosage. And this provides the theory basis for suitable use of surfactant and for improving the effective utilization of pesticide.