Applications of Thermal Imaging in Agriculture—A Review

Abstract

In thermal remote sensing the invisible radiation patterns of objects are converted into visible images and these images are called thermograms or thermal images. Thermal images can be acquired using portable, hand-held or thermal sensors that are coupled with optical systems mounted on an airplane or satellite. This technology is a non-invasive, non-contact and non-destructive technique used to determine thermal properties and features of any object of interest and therefore it can be used in many fields, where heat is generated or lost in space and time. Potential use of thermal remote sensing in agriculture includes nursery and greenhouse monitoring, irrigation scheduling, plants disease detection, estimating fruit yield, evaluating maturity of fruits and bruise detection in fruits and vegetables. This paper reviews the application of thermal imaging in agriculture and its potential use in various agricultural practices.

Plant-Based Methods for Irrigation Scheduling of Woody Crops

“…Ground-based and airborne thermal images can be combined to assess within-orchard spatial heterogeneity in water status, as demonstrated with grape [64] and olive plants [65]. The principles of thermal sensing are described elsewhere [66,67] and nice examples on both the linking between thermal imaging to main physiological indicators [68] and the use of thermal imaging for irrigation scheduling [56,60,66,69] can be found in the literature.…”

An Application of Close-Up Photogrammetry in Viticulture

“…In particular more extensive and demanding field sessions will be carried out to establish how many grape samples, measured by the proposed methodology, can become representative of the vine-yard health status and how they can be related to the ground conditions. In this sense the approach presented in the paper can represent a further example of the precision viticulture that seeks to exploit the widest range of available observations, through unmanned aerial vehicles (UAVs), aircraft or satellites, (Kavvadias et al, 2015;Ishimwe et al, 2014) to describe the vineyards spatial variability with high resolution and provide recommendations to improve management efficiency in terms of quality, production and sustainability.…”

Application of Thermal Imaging in Agriculture and Forestry

“…We conclude that hyperspectral imaging combined with texture analysis can be implemented for fast classification of different varieties of maize seeds." Ishimwe et al (2014) indicated that, according to Hellebrand et al (2002) and Ljungberg & Jonsson (2002), significant positive correlations were found between seedling temperature and damage degree. Thus, IR thermography can be used to detect seed and seedling viability, physical damage, physiological disorders, and to evaluate seed growth processes and plants grown in nurseries and greenhouses.…”

“…Special attention was given to more recent advances such as the use of infrared thermometry and thermography to detect changes in canopy stomatal conductance. Monitoring stomatal conductance (rather than water pontential) may be a better indicator of plant response to drying soil since reductions in conductance can occur before major changes in plant water status that would result in fruit bruising (Ishimwe et al, 2014).…”

“…In the field of biological applications infrared thermography (IRT) is used for visualizing stress induced changes in leaf transpiration". Thermography has been used for scheduling irrigation, assessing soil salinity, disease and pathogen detection, yield estimation, maturity evaluation and bruise detection (Ishimwe et al, 2014). This paper briefly reviews several studies that apply thermal imaging in agriculture and forestry.…”