Open Access

ARTICLE

Leaf Wettability Difference Among Tea Leaf Ages and Analysis Based on Microscopic Surface Features

by Qingmin Pan¹, Yongzong Lu¹, Liang Xue², Yongguang Hu^1,*

1 School of Agricultural Engineering, Jiangsu University, Zhenjiang, 212013, China
2 National Institute of Measurement and Testing Technology, Chengdu, 610021, China

* Corresponding Author: Yongguang Hu. Email:

(This article belongs to the Special Issue: Plant–Environment Interactions)

Phyton-International Journal of Experimental Botany 2023, 92(2), 411-421. https://doi.org/10.32604/phyton.2022.023437

Received 26 April 2022; Accepted 06 June 2022; Issue published 12 October 2022

Abstract

The wettability of leaf surface, commonly represented by contact angle (CA), affects various physiological and physical processes. The present study aims to better understand the wettability of tea leaves and elucidate its influence on the energy barrier of the droplet condensation process. The CA values of different leaf ages (young, mature and old) of five famous tea cultivars (Maolu, longjing 43, Huangjinya, Zhongcha 108 and Anji Baicha) were measured via the sessile drop method, and the micro-morphology of two cultivars leaves (Maolu, Zhongcha 108) was investigated by a 3D super depth-of-field digital microscope. Specifically, two radically distinctive types of CA trends were observed, one was the decreased firstly and then increased slightly with the increase of leaf age, while the other stayed constant. The valley depth or maximum height (R_Z) of Maolu leaf surface increased with the leaf age while the R_Z of Zhongcha 108 leaf remained unchanged by comparing the microscopic features. The Maolu mature leaf CA decline attributed to the young leaf was hydrophilic (θ < 90°), and it was considered that surface structures like folds and pits on old leaf played a crucial role in making CA increased. Small deviation in CA can lead to significant error in calculation of the contact angle function of energy barrier in phase change. It will have great significant for simulating and better understanding the formation of frost on tea leaves.

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Keywords

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