Document Type : Research Paper

Authors

• NOZAR GHAHREMAN
• Azar Sahragard

UNIVERSITY OF TEHRAN

Abstract

Leaf Wetness Duration (LWD) is a key element in plant water balance. Water wets leaf surfaces following various events such as rainfall, dew formation, etc. The result of the interaction between atmosphere and the plant leaf and canopy characteristics determine the leaves wetness duration (LWD) on the plant. This variable is measured by electronic sensors, but, due to the difficulty of measurement, various empirical models using meteorological data have been developed for its estimation. Despite their limitations, these models are widely used. In this study, two empirical models of LWD estimation using relative humidity were evaluated at Paliz station in Fars province. The simplest empirical model uses only the relative humidity (RH), and wetness occurs when the RH is greater than a certain threshold. On the basis of different studies under wet conditions, for several plants, a  threshold value of 87% RH has been determined for this purpose. In this study, the optimized RH-threshold model did a better job compared to non-optimized constant threshold and the extended threshold models in both warm and cold seasons.

Keywords

• Relative Humidity
• Leaf Wetness Sensor
• Empirical model