Influence of tea leaf morphology on water interception for droplet impact

It is common for plant canopy to intercept water during rainfall or sprinkler irrigation. How tea leaves intercept water droplets are unknown. The objective of this study is to investigate the influence of different shapes of tea leaves on the water droplet retention and distribution. First, the shapes of different tea varieties (Zhongcha 108, Maolu, Longjing 43, Huangjinya, and Anji Baicha) were statistically classified, and a high‐speed camera (with a frame rate of 10 000 fps) was used to record and analyse the interception of single droplet. The results showed that the morphology of tea leaves is flat, V‐shaped and hemispherical. The percentage of flat shaped leaves is the highest in each variety (45.38%–63.20%), the proportion of V‐shaped leaves is 30.40%–42.97%, and the proportion of hemispherical leaves is the least. When the impact velocity is 1.35 ± 0.05 m/s, it takes only 20–26 ms for droplet to start hitting each morphology of leaves and be retained as a static liquid. Droplets were kept as a film of water on the flat leaf, and similar situation happened to the hemispherical leaf, but they slid downward due to gravity. When impact position is near the midrib or leaf surface angle is smaller, retained droplets tends to converge to the bottom of the V‐shape with a symmetrical distribution. This study aids to better understand and model water interception within tea canopies for future practice of irrigation and chemical spraying. The morphology of tea tree leaves has been categorized as flat, V‐shaped and hemispherical, and affects droplet impact and retention differently. Droplets were kept as a film on flat leaf, and similar situation happened to the hemispherical leaf, but they slid downward due to gravity. When impact position is near the midrib or leaf surface angle is smaller, retained droplets tends to converge to the V‐shaped leaf bottom with a symmetrical distribution.