Determining the emissivity of the leaves of nine horticultural crops by means of infrared thermography

López, Alejandro López; Molina-Aiz, F.D.; Valera, D.L.; Peña, Araceli

doi:10.1016/j.scienta.2012.01.022

Cited by 78 publications

(66 citation statements)

References 52 publications

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“…Using sonic anemometry would allow the analysis of airflow and temperature distribution inside the greenhouse as in the present work. In addition, thermography would also enable researchers to: (i) study the crop temperature distribution using suitable values of emissivity [25]; (ii) analyze the temperature distribution in the network of warm water pipes, for which it would also be necessary to determine accurately the emissivity of the pipes.…”

Section: Resultsmentioning

confidence: 99%

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Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

López

Valera

Molina-Aiz

et al. 2012

Sensors

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Abstract:The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almerí a's greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W•m −2 ) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C.

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Section: Resultsmentioning

confidence: 99%

“…Emissivity of the upper side of leaves of Cucurbita pepo L. for the spectral infrared range of the infrared camera used in this work was determined at 0.985 [25]. One plant in the central area of the greenhouse was selected to be monitored by measuring its temperature with the thermographic camera every 5 min (Figure 3).…”

Section: Methodsmentioning

confidence: 99%

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

López

Valera

Molina-Aiz

et al. 2012

Sensors

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“…Likewise, we used the same value of T a as a reflected temperature (or commonly known as background radiance) to compute the T leaf ; due to the fact that high emissivity and closed objects allow accurate temperature measurements in almost any background radiance conditions [33]. In addition, to compute T leaf , the emissivity of leaves for the four tree species and seven lianas species was estimated in February 2017 using the reference emissivity technique [34] (data unpublished). The calculation of the T leaf for lianas was performed using the mean value of emissivity (0.983) estimated for this life form, while the calculation for leaves of trees was conducted using the mean value of emissivity determined for each species (A. excelsum = 0.976; A. spraguei = 0.977; C. elastica = 0.976; L. seemannii = 0.980).…”

Section: Estimation Of the Leaf Temperaturementioning

confidence: 99%

Differences in Leaf Temperature between Lianas and Trees in the Neotropical Canopy

Sánchez‐Azofeifa¹,

Rivard²

2018

Forests

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Leaf temperature (T leaf ) influences photosynthesis and respiration. Currently, there is a growing interest in including lianas in productivity models due to their increasing abundance and their detrimental effects in the carbon stock of tropical ecosystems. Therefore, understanding the differences of T leaf between lianas and trees is important for future predictions of productivity. Here, we determined the displayed leaf temperature (T d = T leaf − air temperature) of several species of lianas and their host trees during El Niño-Southern Oscillation (ENSO) and non-ENSO years to evaluate if the presence of lianas affects the T d of their host trees, and if leaves of lianas and their host trees exhibit differences in T d . Our results suggest that close to midday, the presence of lianas does not affect the T d of their host trees; however, lianas tend to have higher values of T d than their hosts across seasons, in both ENSO and non-ENSO years. Although lianas and trees tend to have similar physiological-temperature responses, differences in T d could lead to significant differences in rates of photosynthesis and respiration based on temperature response curves. Future models should thus consider differences in leaf temperature between these two life forms to achieve robust predictions of productivity.

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“…However, a potential source of error is the variation in emissivities between different species and canopy types. Plant leaves have been found to have emissivities between 0.92 and 0.99, and an error of emissivity by 0.026 can give rise to a temperature error of 0.66 °C (Jones, 2004;López et al, 2012). All images were processed using the ExaminIR Pro software (FLIR, Nashua, New Hampshire, U.S.A.) and ImageJ (Rasband, 1997(Rasband, -2014 where leaves, plots, or references were each manually traced and the relevant distribution of temperatures was extracted.…”

Section: Infrared Thermographymentioning

confidence: 99%

Scaling Thermal Properties from the Leaf to the Canopy in the Alaskan Arctic Tundra

Gersony

Prager

Boelman

et al. 2016

Arctic, Antarctic, and Alpine Research

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Plants are strongly influenced by their thermal environments, and this influence manifests itself in a variety of ways, such as altered ranges, growth, morphology, or physiology. However, plants also modify their local thermal environments through feedbacks related to properties and processes such as albedo and evapotranspiration. Here, we used leaf-and plot-level thermography on the north slope of the Brooks Range, Alaska, to explore interspecific differences in thermal properties among arctic tundra plants, and to determine if species differentially contribute to plot temperature. At the leaf-level, we found significant differences (p < 0.05) for in situ temperatures among the 13 study species. At the plot level, we found that the fractional cover of vascular plant species, lichen, litter, and moss had a significant effect on plot temperature (p < 0.05, R 2 = 0.61). A second model incorporating thermal leaf properties-in addition to the fraction of vascular plant and other dominant ground covers-also predicted plot temperature, but with lower explanatory power (p < 0.05, R 2 = 0.32). These results potentially have important implications for our understanding of how individual plant species influence canopylevel thermal properties and how temperature-dependent properties and processes may be impacted by climate change-induced shifts in species composition.

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Determining the emissivity of the leaves of nine horticultural crops by means of infrared thermography

Cited by 78 publications

References 52 publications

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

Differences in Leaf Temperature between Lianas and Trees in the Neotropical Canopy

Scaling Thermal Properties from the Leaf to the Canopy in the Alaskan Arctic Tundra

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