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

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.

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Monitoring Crop Water Status and Irrigation Needs Using Multispectral Airborne Sensors

HortScience ◽

10.21273/hortsci.30.4.905d ◽

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.

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Crop water stress index derived from multi-year ground and aerial thermal images as an indicator of potato water status

Precision Agriculture ◽

10.1007/s11119-014-9351-z ◽

2014 ◽

Vol 15 (3) ◽

pp. 273-289 ◽

Cited By ~ 35

Author(s):

Ronit Rud ◽

Y. Cohen ◽

V. Alchanatis ◽

A. Levi ◽

R. Brikman ◽

...

Keyword(s):

Water Stress ◽

Water Status ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Thermal Images ◽

Water Stress Index ◽

Crop Water Stress

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CROP WATER STRESS INDEX FOR PREDICTING YIELD LOSS IN COMMON BEAN

Irriga ◽

10.15809/irriga.2021v1n4p687-695 ◽

2022 ◽

Vol 1 (4) ◽

pp. 687-695

Author(s):

Carlos Quiloango-Chimarro ◽

Rubens Duarte Coelho ◽

Jéfferson de Oliveira Costa ◽

Rafael Gomez-Arrieta

Keyword(s):

Water Stress ◽

Grain Yield ◽

Common Bean ◽

Yield Loss ◽

Canopy Temperature ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Water Stress Index ◽

Crop Water Stress

The crop water stress index (CWSI), an index derived from canopy temperature, has been widely studied as a physiological indicator of plant water status to optimize irrigation in common beans. However, it is not clear how this index could contribute to yield prediction as a decision support tool in irrigation management. This paper aimed to use the CWSI for predicting yield loss in common bean (Phaseolus vulgaris L.) subjected to water stress under drip irrigation. A rain shelter experiment was conducted using a completely randomized design with five replications. The indeterminate growth cultivar TAA Dama was subjected to three irrigation treatments: 100% of the field capacity (FC), 75 and 50% FC from 20 days after sowing (DAS) until the end of the crop cycle. Grain yield was reduced by 42% under 50% FC treatment. Furthermore, stomatal conductance was reduced under this treatment, whereas the CWSI and canopy temperature increased as irrigation levels decreased. The relationship between grain yield and CWSI (R2=0.76, RSME=2.35g) suggests that canopy temperature data could be used to forecast grain yield losses. In conclusion, farmers can have a low-cost, effective technique for making water management decisions in common bean.

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Determination of Crop Water Stress Index by Infrared Thermometry in Grapefruit Trees Irrigated with Saline Reclaimed Water Combined with Deficit Irrigation

Remote Sensing ◽

10.3390/rs11070757 ◽

2019 ◽

Vol 11 (7) ◽

pp. 757 ◽

Cited By ~ 3

Author(s):

Cristina Romero-Trigueros ◽

José María Bayona Gambín ◽

Pedro Antonio Nortes Tortosa ◽

Juan José Alarcón Cabañero ◽

Emilio Nicolás Nicolás

Keyword(s):

Water Stress ◽

Water Status ◽

Reclaimed Water ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Infrared Thermometry ◽

Water Stress Index ◽

Thermal Indicators ◽

Crop Water Stress

Water is not always accessible for agriculture due to its scarcity. In order to successfully develop irrigation strategies that optimize water productivity characterization of the plant, the water status is necessary. We assessed the suitability of thermal indicators by infrared thermometry (IRT) to determine the water status of grapefruit in a commercial orchard with long term irrigation using saline reclaimed water (RW) and regulated deficit irrigation (RDI) in Southeastern Spain. The results showed that Tc-Ta differences were positive in a wide range of vapor pressure deficits (VPD), and the major Tc-Ta were found at 10.00 GMT, before and after the highest daily values of VPD and solar radiation, respectively, were reached. In addition, we evaluated the relationships between Tc-Ta and VPD to establish the Non-Water Stressed Baselines (NWSBs), which are necessary to accurately calculate the crop water stress index (CWSI). Two important findings were found, which include i) the best significant correlations (p < 0.005) found at 10.00 GMT and their slopes were positive, and ii) NWSBs showed a marked hourly and seasonal variation. The hourly shift was mainly explained by the variation in solar radiation since both the NWSB-slope and the NWSB-intercept were significantly correlated with a zenith solar angle (θZ) (p < 0.005). The intercept was greater when θZ was close to 0 (at midday) and the slope displayed a marked hysteresis throughout the day, increasing in the morning and decreasing in the afternoon. The NWSBs determination, according to the season improved most of their correlation coefficients. In addition, the relationship significance of Tc-Ta versus VPD was higher in the period where the intercept and Tc-Ta were low. CWSI was the thermal indicator that showed the highest level of agreement with the stem water potential of the different treatments even though Tc and Tc-Ta were also significantly correlated. We highlight the suitability of thermal indicators measured by IRT to determine the water status of grapefruits under saline (RW) and water stress (RDI) conditions.

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Quantifying Water Status of Safflower (Carthamus Tinctorius L.) Cultivars by Crop Water Stress Index Under Different Irrigation Regimes

SSRN Electronic Journal ◽

10.2139/ssrn.3943405 ◽

2021 ◽

Author(s):

Ehsan Bijanzadeh ◽

Seyed Mojtaba Mosavi ◽

Fatemeh Bahadori

Keyword(s):

Water Stress ◽

Water Status ◽

Carthamus Tinctorius ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Water Stress Index ◽

Irrigation Regimes ◽

Crop Water Stress

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Using a crop water stress index based on a sap flow method to estimate water status in conilon coffee plants

Agricultural Water Management ◽

10.1016/j.agwat.2020.106343 ◽

2020 ◽

Vol 241 ◽

pp. 106343

Author(s):

Afonso Zucolotto Venturin ◽

Claudinei Martins Guimarães ◽

Elias Fernandes de Sousa ◽

José Altino Machado Filho ◽

Weverton Pereira Rodrigues ◽

...

Keyword(s):

Water Stress ◽

Sap Flow ◽

Water Status ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Flow Method ◽

Water Stress Index ◽

Coffee Plants ◽

Crop Water Stress

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Evaluation of the Crop Water Stress Index as an Indicator for the Diagnosis of Grapevine Water Deficiency in Greenhouses

Horticulturae ◽

10.3390/horticulturae6040086 ◽

2020 ◽

Vol 6 (4) ◽

pp. 86

Author(s):

Chen Ru ◽

Xiaotao Hu ◽

Wene Wang ◽

Hui Ran ◽

Tianyuan Song ◽

...

Keyword(s):

Water Stress ◽

Water Status ◽

Leaf Temperature ◽

Stress Index ◽

Plant Water ◽

Crop Water ◽

Crop Water Stress Index ◽

Water Stress Index ◽

The Relationship ◽

Crop Water Stress

Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study evaluated the applicability of crop water stress index (CWSI) based on the leaf temperature for diagnosing the grapevine water status. The experiment was conducted at Yuhe Farm (northwest China), with drip-irrigated grapevines under three irrigation treatments. Meteorological factors, soil moisture contents, leaf temperature, growth indicators including canopy coverage and fruit diameter, and physiological indicators including SPAD (relative chlorophyll content), stem water potential (φs), stomatal conductance (gs), and transpiration rate (E) were studied during the growing season. The results show that the relationship between the leaf-air temperature difference (Tc-Ta) and the plant water status indicators (φs, gs, E) were significant (P < 0.05), and the relationship between gs, E and Tc-Ta was the closest, with R2 values ranging from 0.530–0.604 and from 0.545–0.623, respectively. CWSI values are more easily observed on sunny days, and it was determined that 14:00 BJS is the best observation time for the CWSI value under different non-water-stressed baselines. There is a reliable linear correlation between the CWSI value and the soil moisture at 0–40 cm (P < 0.05), which could provide a reference when using the CWSI to diagnose the water status of plants. Compared with the Tc-Ta value, the CWSI could more accurately monitor the plant water status, and above the considered indictors, gs has the greatest correlation with the CWSI.

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Application of a Daily Crop Water Stress Index to Deficit Irrigate Malbec Grapevine under Semi-Arid Conditions

Agriculture ◽

10.3390/agriculture10110492 ◽

2020 ◽

Vol 10 (11) ◽

pp. 492

Author(s):

Krista C. Shellie ◽

Bradley A. King

Keyword(s):

Water Stress ◽

Water Status ◽

Irrigation Scheduling ◽

Stress Index ◽

Crop Water ◽

Crop Water Stress Index ◽

Irrigation Amount ◽

Water Stress Index ◽

Arid Conditions ◽

Crop Water Stress

Precision irrigation of wine grape is hindered by the lack of an automated method for monitoring vine water status. The objectives of this study were to: Validate an automated model for remote calculation of a daily crop water stress index (CWSI) for the wine grape (Vitis vinifera L.) cultivar Malbec and evaluate its suitability for use in irrigation scheduling. Vines were supplied weekly with different percentages of evapotranspiration-based estimated water demand (ETc) over four growing seasons. In the fifth growing season, different daily CWSI threshold values were used to trigger an irrigation event that supplied 28 mm of water. All three indicators of vine water status (CWSI, midday leaf water potential (Ψlmd), and juice carbon isotope ratio (δ13C)) detected an increase in stress severity as the irrigation amount decreased. When the irrigation amount decreased from 100% to 50% ETc, 70% to 35% ETc, or the daily CWSI threshold value increased from 0.4 to 0.6, berry fresh weight and juice titratable acidity decreased, juice δ13C increased, the weekly CWSI increased, and Ψlmd decreased. Under the semi-arid conditions of this study, utilizing a daily CWSI threshold for irrigation scheduling reduced the irrigation amount without compromising the yield or changes in berry composition and remotely provided automated decision support for managing water stress severity in grapevine.

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