School of Mathematical Sciences, Queensland University of Technology, Brisbane, Australia.
TERRA Research and Teaching Centre, Gembloux Agro Bio-Tech, University of Liège, Gembloux, Belgium.
Pest Manag Sci. 2020 Oct;76(10):3477-3486. doi: 10.1002/ps.5796. Epub 2020 Mar 3.
A key challenge for developing computer models of spray retention by plants is to accurately predict how spray drops behave when impacting leaf surfaces. One poorly understood outcome occurs when drops bounce or shatter on impact but leave behind a proportion of the liquid on the surface (designated as pinning). This process is studied via impaction experiments with two hard-to-wet leaf surfaces (fat-hen: Chenopodium album and barnyard grass: Echinochloa crus-galli L. P. Beauv) and one hydrophobic artificial surface (Teflon) using three liquid formulations.
Drops that impact upon Teflon underwent pinning shatter events via a well-known mechanism referred to as receding breakup. Drops impacting on leaf surfaces did not undergo receding breakup because the liquid rim was not in direct contact with the leaf surface when it broke into secondary droplets. However, pinning did occur on plant surfaces via a different mechanism, especially when using formulations containing a surfactant.
Newly developed image analysis and methodology has allowed quantification of the volume fraction pinned to surfaces when drops shatter. The addition of surfactant can increase both the probability of pinning and the pinned volume when drops shatter on fat-hen or Teflon. However, the surfactants studied did not substantially improve the probability of pinning on barnyard grass. The difference in behaviour between the two leaf surfaces and the underlying mechanism is worth further study. © 2020 Society of Chemical Industry.
开发植物喷雾保留计算机模型的一个关键挑战是准确预测喷雾液滴在撞击叶片表面时的行为。一种理解不佳的结果是，当液滴在撞击时反弹或破碎，但在表面留下一部分液体（称为固定）时发生。通过使用三种液体配方，对两种难以润湿的叶片表面（Chenopodium album 和 Echinochloa crus-galli L. P. Beauv）和一种疏水人工表面（特氟龙）进行撞击实验来研究该过程。
撞击特氟龙的液滴会通过一种称为后退破裂的众所周知的机制发生固定破碎事件。撞击叶片表面的液滴不会发生后退破裂，因为当液滴分裂成次级液滴时，液滴边缘并未直接与叶片表面接触。然而，固定确实会在植物表面发生，特别是当使用含有表面活性剂的配方时。
新开发的图像分析和方法学允许量化液滴破碎时固定在表面的体积分数。当液滴在 Chenopodium album 或特氟龙上破碎时，表面活性剂的添加可以增加固定的概率和固定的体积。然而，研究的表面活性剂并没有显著提高液滴在 Echinochloa crus-galli L. P. Beauv 上固定的概率。两种叶片表面之间的行为差异及其潜在机制值得进一步研究。© 2020 英国化学工业学会。
