scholarly journals A New Low-Cost Device Based on Thermal Infrared Sensors for Olive Tree Canopy Temperature Measurement and Water Status Monitoring

2020 ◽  
Vol 12 (4) ◽  
pp. 723 ◽  
Author(s):  
Miguel Noguera ◽  
Borja Millán ◽  
Juan José Pérez-Paredes ◽  
Juan Manuel Ponce ◽  
Arturo Aquino ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Low Cost ◽  
Canopy Temperature ◽  
Olive Tree ◽  
Thermal Infrared ◽  
Tree Canopy ◽  
Coefficient Of Determination ◽  
Crop Water ◽  
Olive Orchard

In recent years, many olive orchards, which are a major crop in the Mediterranean basin, have been converted into intensive or super high-density hedgerow systems. This configuration is more efficient in terms of yield per hectare, but at the same time the water requirements are higher than in traditional grove arrangements. Moreover, irrigation regulations have a high environmental (through water use optimization) impact and influence on crop quality and yield. The mapping of (spatio-temporal) variability with conventional water stress assessment methods is impractical due to time and labor constraints, which often involve staff training. To address this problem, this work presents the development of a new low-cost device based on a thermal infrared (IR) sensor for the measurement of olive tree canopy temperature and monitoring of water status. The performance of the developed device was compared to a commercial thermal camera. Furthermore, the proposed device was evaluated in a commercially managed olive orchard, where two different irrigation treatments were established: a full irrigation treatment (FI) and a regulated deficit irrigation (RDC), aimed at covering 100% and 50% of crop evapotranspiration (ETc), respectively. Predawn leaf water potential (ΨPD) and stomatal conductance (gs), two widely accepted indicators for crop water status, were regressed to the measured canopy temperature. The results were promising, reaching a coefficient of determination R2 ≥ 0.80. On the other hand, the crop water stress index (CWSI) was also calculated, resulting in a coefficient of determination R2 ≥ 0.79. The outcomes provided by the developed device support its suitability for fast, low-cost, and reliable estimation of an olive orchard’s water status, even suppressing the need for supervised acquisition of reference temperatures. The newly developed device can be used for water management, reducing water usage, and for overall improvements to olive orchard management.

Assessing canopy temperature-based water stress indices for soybeans under subhumid conditions

2020 ◽  
Author(s):  
Angela Morales Santos ◽  
Reinhard Nolz
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Status ◽  
Canopy Temperature ◽  
Irrigation Scheduling ◽  
Stress Index ◽  
Crop Water ◽  
Stress Indices ◽  
Soil Water Status ◽  
Crop Water Stress

<p>Sustainable irrigation water management is expected to accurately meet crop water requirements in order to avoid stress and, consequently, yield reduction, and at the same time avoid losses of water and nutrients due to deep percolation and leaching. Sensors to monitor soil water status and plant water status (in terms of canopy temperature) can help planning irrigation with respect to time and amounts accordingly. The presented study aimed at quantifying and comparing crop water stress of soybeans irrigated by means of different irrigation systems under subhumid conditions.</p><p>The study site was located in Obersiebenbrunn, Lower Austria, about 30 km east of Vienna. The region is characterized by a mean temperature of 10.5°C with increasing trend due to climate change and mean annual precipitation of 550 mm. The investigations covered the vegetation period of soybean in 2018, from planting in April to harvest in September. Measurement data included precipitation, air temperature, relative humidity and wind velocity. The experimental field of 120x120 m<sup>2</sup> has been divided into four sub-areas: a plot of 14x120 m<sup>2</sup> with drip irrigation (DI), 14x120 m<sup>2</sup> without irrigation (NI), 36x120 m<sup>2</sup> with sprinkler irrigation (SI), and 56x120 m<sup>2</sup> irrigated with a hose reel boom with nozzles (BI). A total of 128, 187 and 114 mm of water were applied in three irrigation events in the plots DI, SI and BI, respectively. Soil water content was monitored in 10 cm depth (HydraProbe, Stevens Water) and matric potential was monitored in 20, 40 and 60 cm depth (Watermark, Irrometer). Canopy temperature was measured every 15 minutes using infrared thermometers (IRT; SI-411, Apogee Instruments). The IRTs were installed with an inclination of 45° at 1.8 m height above ground. Canopy temperature-based water stress indices for irrigation scheduling have been successfully applied in arid environments, but their use is limited in humid areas due to low vapor pressure deficit (VPD). To quantify stress in our study, the Crop Water Stress Index (CWSI) was calculated for each plot and compared to the index resulting from the Degrees Above Canopy Threshold (DACT) method. Unlike the CWSI, the DACT method does not consider VPD to provide a stress index nor requires clear sky conditions. The purpose of the comparison was to revise an alternative method to the CWSI that can be applied in a humid environment.</p><p>CWSI behaved similar for the four sub-areas. As expected, CWSI ≥ 1 during dry periods (representing severe stress) and it decreased considerably after precipitation or irrigation (representing no stress). The plot with overall lower stress was BI, producing the highest yield of the four plots. Results show that DACT may be a more suitable index since all it requires is canopy temperature values and has strong relationship with soil water measurements. Nevertheless, attention must be paid when defining canopy temperature thresholds. Further investigations include the development and test of a decision support system for irrigation scheduling combining both, plant-based and soil water status indicators for water use efficiency analysis.</p>

scholarly journals Challenges and Future Perspectives of Multi-/Hyperspectral Thermal Infrared Remote Sensing for Crop Water-Stress Detection: A Review

2019 ◽  
Vol 11 (10) ◽  
pp. 1240 ◽  
Author(s):  
Max Gerhards ◽  
Martin Schlerf ◽  
Kaniska Mallick ◽  
Thomas Udelhoven
Keyword(s):  
Remote Sensing ◽  
Water Stress ◽  
Water Status ◽  
Thermal Infrared ◽  
Hyperspectral Remote Sensing ◽  
Plant Responses ◽  
Plant Water ◽  
Stress Detection ◽  
Crop Water ◽  
Crop Water Stress

Thermal infrared (TIR) multi-/hyperspectral and sun-induced fluorescence (SIF) approaches together with classic solar-reflective (visible, near-, and shortwave infrared reflectance (VNIR)/SWIR) hyperspectral remote sensing form the latest state-of-the-art techniques for the detection of crop water stress. Each of these three domains requires dedicated sensor technology currently in place for ground and airborne applications and either have satellite concepts under development (e.g., HySPIRI/SBG (Surface Biology and Geology), Sentinel-8, HiTeSEM in the TIR) or are subject to satellite missions recently launched or scheduled within the next years (i.e., EnMAP and PRISMA (PRecursore IperSpettrale della Missione Applicativa, launched on March 2019) in the VNIR/SWIR, Fluorescence Explorer (FLEX) in the SIF). Identification of plant water stress or drought is of utmost importance to guarantee global water and food supply. Therefore, knowledge of crop water status over large farmland areas bears large potential for optimizing agricultural water use. As plant responses to water stress are numerous and complex, their physiological consequences affect the electromagnetic signal in different spectral domains. This review paper summarizes the importance of water stress-related applications and the plant responses to water stress, followed by a concise review of water-stress detection through remote sensing, focusing on TIR without neglecting the comparison to other spectral domains (i.e., VNIR/SWIR and SIF) and multi-sensor approaches. Current and planned sensors at ground, airborne, and satellite level for the TIR as well as a selection of commonly used indices and approaches for water-stress detection using the main multi-/hyperspectral remote sensing imaging techniques are reviewed. Several important challenges are discussed that occur when using spectral emissivity, temperature-based indices, and physically-based approaches for water-stress detection in the TIR spectral domain. Furthermore, challenges with data processing and the perspectives for future satellite missions in the TIR are critically examined. In conclusion, information from multi-/hyperspectral TIR together with those from VNIR/SWIR and SIF sensors within a multi-sensor approach can provide profound insights to actual plant (water) status and the rationale of physiological and biochemical changes. Synergistic sensor use will open new avenues for scientists to study plant functioning and the response to environmental stress in a wide range of ecosystems.

scholarly journals Simulating Canopy Temperature Using a Random Forest Model to Calculate the Crop Water Stress Index of Chinese Brassica

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2244
Author(s):  
Mingxin Yang ◽  
Peng Gao ◽  
Ping Zhou ◽  
Jiaxing Xie ◽  
Daozong Sun ◽  
...  
Keyword(s):  
Water Stress ◽  
Random Forest ◽  
Water Status ◽  
Canopy Temperature ◽  
Random Forest Model ◽  
Stress Index ◽  
Crop Water ◽  
Crop Water Stress Index ◽  
Forest Model ◽  
Water Stress Index

The determination of crop water status has positive effects on the Chinese Brassica industry and irrigation decisions. Drought can decrease the production of Chinese Brassica, whereas over-irrigation can waste water. It is desirable to schedule irrigation when the crop suffers from water stress. In this study, a random forest model was developed using sample data derived from meteorological measurements including air temperature (Ta), relative humidity (RH), wind speed (WS), and photosynthetic active radiation (Par) to predict the lower baseline (Twet) and upper baseline (Tdry) canopy temperatures for Chinese Brassica from 27 November to 31 December 2020 (E1) and from 25 May to 20 June 2021 (E2). Crop water stress index (CWSI) values were determined based on the predicted canopy temperature and used to assess the crop water status. The study demonstrated the viability of using a random forest model to forecast Twet and Tdry. The coefficients of determination (R2) in E1 were 0.90 and 0.88 for development and 0.80 and 0.77 for validation, respectively. The R2 values in E2 were 0.91 and 0.89 for development and 0.83 and 0.80 for validation, respectively. Our results reveal that the measured and predicted CWSI values had similar R2 values related to stomatal conductance (~0.5 in E1, ~0.6 in E2), whereas the CWSI showed a poor correlation with transpiration rate (~0.25 in E1, ~0.2 in E2). Finally, the methodology used to calculate the daily CWSI for Chinese Brassica in this study showed that both Twet and Tdry, which require frequent measuring and design experiment due to the trial site and condition changes, have the potential to simulate environmental parameters and can therefore be applied to conveniently calculate the CWSI.

Linking canopy temperature and trunk diameter fluctuations with other physiological water status tools for water stress management in citrus orchards

2011 ◽  
Vol 38 (2) ◽  
pp. 106 ◽  
Author(s):  
Iván F. García-Tejero ◽  
Víctor H. Durán-Zuazo ◽  
José L. Muriel-Fernández ◽  
Juan A. Jiménez-Bocanegra
Keyword(s):  
Water Stress ◽  
Deficit Irrigation ◽  
Water Status ◽  
Irrigation Treatment ◽  
Canopy Temperature ◽  
Control Treatment ◽  
Stem Water Potential ◽  
Crop Water ◽  
Trunk Diameter ◽  
Trunk Diameter Fluctuations

The continuous monitoring of crop water status is key to the sustainable management of water stress situations. Two deficit irrigation (DI) treatments were studied during the maximum evapotranspirative demand period in an orange orchard (Citrus sinensis (L.) Osb. cv. Navelina): sustained deficit irrigation irrigated at 55% crop evapotranspiration (ETC), and low-frequency deficit irrigation treatment, in which the plants were irrigated according to stem water potential at midday (Ψstem). Additionally, a control treatment irrigated at 100% of ETC was established. The daily canopy temperature (TC) was measured with an infrared thermometer camera together with measurements of trunk diameter fluctuations (TDF), Ψstem and stomatal conductance (gS). The time course of all physiological parameters and their relationships were analysed, confirming that canopy air temperature differential (TC – Ta) variations and TDF are suitable approaches for determining the water stress. In addition, the maximum daily shrinkage (MDS) and TC – Ta showed high sensitivity to water stress in comparison to Ψstem and gS. Significant relationships were found among MDS and TC – Ta with Ψstem and gS, for monitoring the crop water status by means of MDS vs Ψstem and TC – Ta vs Ψstem. Thus, the combination of these techniques would be useful for making scheduling decisions on irrigation in orchards with high variability in plant water stress.

scholarly journals Prediction of Olive Tree Water Requirements under Limited Soil Water Availability, Based on Sap Flow Estimations

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1318
Author(s):  
Efthimios Kokkotos ◽  
Anastasios Zotos ◽  
George Tsirogiannis ◽  
Angelos Patakas
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Availability ◽  
Reference Evapotranspiration ◽  
Water Status ◽  
Low Cost ◽  
Olive Tree ◽  
Thermal Dissipation ◽  
Soil Water Availability ◽  
Water Losses

The forecast of irrigation requirements in commercial olive orchards in the era of climate change is at the forefront of scientific research. Simplified models that are based on monitoring soil and plant water status, along with microclimatic variables are well established. In the present study, an attempt was made to correlate the olive tree sap fluxes and the theoretical grass water losses, as expressed by reference evapotranspiration (ETo) in mild to moderate water-stress conditions. The water flow in the soil–plant–air continuum was monitored using soil water and thermal dissipation probes (TDP), which have a comparatively low cost and satisfactory reliability, while microclimatic variability was monitored by a meteorological station placed within the experimental orchard. The assessment of water stress was conducted via a stress coefficient (Ks), which was determined according to soil water availability, and validated with measurements of pre-dawn water potential and stomatal conductance. The results suggest the existence of an exponential correlation (R2 = 0.869) between daily plant transpirational losses and reference evapotranspiration, while the methodology’s applicability is verified by the validation process (R2 = 0.804 and RMSE = 0.579 L per day).

scholarly journals Assessing the Water-Stress Baselines by Thermal Imaging for Irrigation Management in Almond Plantations under Water Scarcity Conditions

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1298
Author(s):  
Saray Gutiérrez-Gordillo ◽  
Iván Francisco García-Tejero ◽  
Víctor Hugo Durán Zuazo ◽  
Amelia García Escalera ◽  
Fernando Ferrera Gil ◽  
...  
Keyword(s):  
Water Stress ◽  
Thermal Imaging ◽  
Water Status ◽  
Irrigation Management ◽  
Irrigation Treatment ◽  
Canopy Temperature ◽  
Irrigation Scheduling ◽  
Stress Index ◽  
Crop Water ◽  
Crop Water Stress Index

This work examines the use of thermal imaging to determine the crop water status in young almond trees under sustained deficit irrigation strategies (SDIs). The research was carried out during two seasons (2018–2019) in three cultivars (Prunus dulcis Mill., cvs. Guara, Lauranne, and Marta) subjected to three irrigation treatments: a full irrigation treatment (FI) at 100% of irrigation requirements (IR), and two SDIs that received 75% and 65% of the IR, respectively. Crop water monitoring was done by measurements of canopy temperature, leaf water potential (Ψleaf), and stomatal conductance. Thermal readings were used to define the non-water-stress baselines (NWSB) and water-stress baselines (WSB) for each treatment and cultivar. According to our findings, Ψleaf was the most responsive parameter to reflect differences in almond water status. In addition, NWSB and WSB allowed the determination of the crop water-stress index (CWSI) and the increment of canopy temperature (ITC) for each SDI treatment, obtaining threshold values of CWSI (0.12–0.15) and ITC (~1 °C) that would ensure maximum water savings by minimizing the effects on yield. The findings highlight the importance of determining the different NWSB and WSB for different almond cultivars and its potential use for proper irrigation scheduling.

Monitoring Crop Water Status and Irrigation Needs Using Multispectral Airborne Sensors

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 905D-905
Author(s):  
Thomas R. Clarke ◽  
M. Susan Moran
Keyword(s):  
Water Stress ◽  
Near Infrared ◽  
Water Status ◽  
Canopy Cover ◽  
Stress Index ◽  
Crop Water ◽  
Vegetative Cover ◽  
Crop Water Stress Index ◽  
Water Stress Index ◽  
Subsurface Drip

Water application efficiency can be improved by directly monitoring plant water status rather than depending on soil moisture measurements or modeled ET estimates. Plants receiving sufficient water through their roots have cooler leaves than those that are water-stressed, leading to the development of the Crop Water Stress Index based on hand-held infrared thermometry. Substantial error can occur in partial canopies, however, as exposed hot soil contributes to deceptively warm temperature readings. Mathematically comparing red and near-infrared reflectances provides a measure of vegetative cover, and this information was combined with thermal radiance to give a two-dimensional index capable of detecting water stress even with a low percentage of canopy cover. Thermal, red, and near-infrared images acquired over subsurface drip-irrigated cantaloupe fields demonstrated the method's ability to detect areas with clogged emitters, insufficient irrigation rate, and system water leaks.

On-the-go thermal imaging for water status assessment in commercial vineyards

2017 ◽  
Vol 8 (2) ◽  
pp. 520-524
Author(s):  
S. Gutiérrez ◽  
M. P. Diago ◽  
J. Fernández-Novales ◽  
J. Tardaguila
Keyword(s):  
Thermal Imaging ◽  
Water Status ◽  
Canopy Temperature ◽  
Stress Index ◽  
Coefficient Of Determination ◽  
Stem Water Potential ◽  
Water Stress Index ◽  
Status Assessment ◽  
Commercial Vineyard ◽  
East And West

The goal of this work was the assessment of commercial vineyard water status using on-the-go thermal imaging. On-the-go thermal imaging acquisition was conducted with a thermal camera operating at 1.20 m distance from the canopy, mounted on a quad moving at 5 km/h. Canopy temperature, cross water stress index (CWSI) and stomatal conductance index (Ig) were strongly and significantly correlated to stem water potential (Ψstem) in east and west side of the canopy. For CWSI, the values of the coefficient of determination (R2) were 0.88*** and 0.73*** for east and west sides, respectively. As regards the index Ig, its relationships with Ψstem showed R2=0.89*** and R2=0.77*** for east and west sides, respectively. These results are promising and evidence the potential of on-the-go thermal imaging to become a new tool to evaluate the vineyard water status.

On the use of different approaches based on photochemical reflectance index and surface temperature to monitor the water status of winter wheat in semi-arid regions

2020 ◽  
Author(s):  
Zoubair Rafi ◽  
Valérie Le Dantec ◽  
Olivier Merlin ◽  
Said Khabba ◽  
Patrick Mordelet ◽  
...  
Keyword(s):  
Water Stress ◽  
Winter Wheat ◽  
Surface Temperature ◽  
Water Status ◽  
Stress Index ◽  
Coefficient Of Determination ◽  
Temperature Index ◽  
Water Stress Index ◽  
Semi Arid

<p>Agriculture is considered to be the human activity that consumes the most mobilized water on a global scale. However, crops planted in semi-arid areas regularly face periods of moderate to extreme water stress. Such water stress periods have a considerable impact on the seasonal yield of these crops. In order to participate in a more rational irrigation water management, monitoring of the rapid changes in plant water status is necessary. For this purpose, the combination of two different wavelength ranges will be explored : an index based on Xanthophyll cycle (Photochemical Reflectance Index, PRI) and a commonly-used index from thermal infrared spectral range (LST). An experiment on winter wheat was carried out over two agricultural campaigns (2016 to 2018) in the Haouz basin, which is located in the Marrakech region, to better assimilate the temporal dynamics of PRI and surface temperature. In this study, four different approaches are proposed to study the functioning of wheat : 1- an approach based on solar angle to remove the structure effect (PRI<sub>0</sub>) from the PRI signal and to derive a water stress index PRI<sub>j</sub>, 2- an approach based on global radiation (R<sub>g</sub>) to extrapolate a theoretical PRI (PRI<sub>th</sub>) for R<sub>g</sub> equal to zero and to calculate a water stress index PRI<sub>lin</sub>, 3- an approach that determines an optimal PRI (PRI<sub>pot</sub>) on the basis of the available water content (AWC) criterion in order to derive a stress index I-PRI and 4- an energy balance approach to extract dry and wet surface temperatures in order to establish a normalized surface temperature index (T<sub>norm</sub>). The results of this work show a strong correlation between the PRI<sub>0</sub> and the Leaf Area Index with a coefficient of determination equal to 0.92, indicating that it is possible to isolate the structural effects of wheat on the PRI signal. In addition, over the range of variation in AWC, a significant correlation with PRI<sub>j</sub>, PRI<sub>jlin</sub> and I-PRI was observed with coefficients of determination of 0.71, 0.42 and 0.24, respectively. In contrast to the T<sub>norm</sub>, which varies only for values of AWC below 30%, a coefficient of determination of 0.22 is obtained. Finally, the PRI allows us to acquire early and complete information on the response of wheat to change in AWC as opposed to the surface temperature index, revealing the potential of the PRI to monitor the water status of plants and their responses to changing environmental conditions.</p>

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