Abstract
Radar backscatter from a vegetated surface is sensitive to direct backscatter from the canopy and two-way attenuation of the signal as it travels through the canopy. Both mechanisms are affected by the dielectric properties of the individual elements of the canopy, which are primarily a function of water content. Leaf water content of corn can change considerably during the day and in response to water stress, and model simulations suggested that this significantly affects radar backscatter. Understanding the influence of water stress on leaf dielectric properties will give insight into how the plant water status changes in response to water stress and how radar can be used to detect vegetation water stress. We used a microstrip line resonator to monitor the changes in its resonant frequency at corn leaves, due to variations in dielectric properties. This letter presents the in vivo resonant frequency measurements during field experiments with and without water stress, to understand the dielectric response due to stress. The resonant frequency of the leaf around the main leaf of the stressed plant showed increasing diurnal differences. The dielectric response of the unstressed plant remained stable. This letter shows the clear statistically significant effect of water stress on variations in resonant frequency at individual leaves.
Highlights
T HIS letter is motivated by the potential use of radar for early water stress detection in agricultural canopies
This letter shows that after the onset of water stress, the dielectric response of the leaves around the ear is mainly affected. The results of this first field application are promising, as these results demonstrate the dynamic behavior of leaf dielectric constant
The leaf dielectric properties change with time and their response to plant growth and water stress depends on the height and age of the leaf
Summary
T HIS letter is motivated by the potential use of radar for early water stress detection in agricultural canopies. Radar backscatter is sensitive to vegetation because of the direct backscatter from the canopy itself and two-way attenuation of the signal as it travels through the canopy. Both mechanisms are affected by the dielectric constant, architecture, shape, and orientation of all individual scattering elements (leaves, branches, stem, and fruits) within the canopy. The dielectric properties of these individual scatterers are primarily a function of water content and depend on salinity [1] and temperature [2].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have