Stomatal conductance and photosynthesis in water hyacinth: Effects of removing water from roots as quantified by a foliage-temperature-based plant water stress index☆

1984 ◽  
Vol 32 (3-4) ◽  
pp. 249-256 ◽  
Author(s):  
S IDSO ◽  
P PINTERJR ◽  
R REGINATO ◽  
K CLAWSON
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Hyacinth ◽  
Stress Index ◽  
Plant Water ◽  
Plant Water Stress ◽  
Water Stress Index

scholarly journals Stem Water Potential and Apple Size

1995 ◽  
Vol 120 (4) ◽  
pp. 577-582 ◽  
Author(s):  
Amos Naor ◽  
Isaac Klein ◽  
Israel Doron
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Fruit Size ◽  
Plant Water ◽  
Stem Water Potential ◽  
Plant Water Stress ◽  
Stem Water ◽  
Irrigation Treatments ◽  
Highly Correlated

The sensitivity of leaf (ψleaf) and stem (ψstem) water potential and stomatal conductance (gs) to soil moisture availability in apple (Malus domestics Borkh.) trees and their correlation with yield components were studied in a field experiment. Two drip irrigation treatments, 440 mm (H) and 210 mm (L), were applied to a `Golden Delicious' apple orchard during cell enlargement stage (55-173 days after full bloom). Data collected included ψstem, y leaf, gs, and soil water potential at 25 (ψsoil-25) and 50 cm (ψsoil-50). No differences in midday ψleaf's were found between irrigation treatments. Stem water potential was higher in the H treatment than in the L treatment in diurnal measurements, and at midday throughout the season. Stomatal conductance of the H treatment was higher than the L treatment throughout the day. Stomatal conductance between 0930 and 1530 hr were highly correlated with ψstem. The H treatment increased the percentage of fruit >65 mm, and increased the proportion of earlier harvested fruit reaching marketable size compared to the L treatment. Fruit size in the first harvest and the total yield were highly correlated with ψstem. The degree of correlation between plant water stress indicators and yield component decreased in the following order: ψstem>ψsoil-25,>ψsoil-50>ψleaf. The data suggest that midday ψstem may serve as a preferable plant water stress indicator with respect to fruit size.

scholarly journals Evaluation of Water Stress Impact on the Parameter Values in Stomatal Conductance Models Using Tower Flux Measurement of a Boreal Aspen Forest

2012 ◽  
Vol 13 (1) ◽  
pp. 239-254 ◽  
Author(s):  
Shusen Wang
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Flux Measurement ◽  
Relative Reduction ◽  
Model Parameters ◽  
Plant Water ◽  
Plant Water Stress ◽  
Aspen Forest ◽  
Parameter Values ◽  
The Impact

Abstract The impact of water stress on plant stomatal conductance (g) has been widely studied but with little consensus as to the processes governing its responses. The photosynthesis-driven stomatal conductance models usually employ constant model parameters and attribute the decrease of g from water stress to the reduction of leaf photosynthesis. This has been challenged by studies showing that the model parameter values decrease when the plant is under water stress. In this study, the impact of plant water stress on the parameter values in stomatal conductance models is evaluated using the approach recently developed by S. Wang et al. and the tower flux measurements at a Canadian boreal aspen forest. Results show that the slope parameter (α) in the stomatal conductance models decreases substantially with the development of plant water stress. The magnitude of this reduction is dependent on how plant water stress is represented. Overall, the relative reduction of α from its maximum value is 28% when soil water content decreases from 0.38 to 0.18 m3 m−3, and is 38% when Bowen ratio increases from 0.25 to 3.5. Equations for α correction to account for water stress impacts are proposed. Further studies on different ecosystems are necessary to quantify the parameter variations with water stress among different climate regions and plant species.

Estimation of Stomatal Conductance using Crop Water Stress Index based on the Thermal Image at a Leaf Scale

2020 ◽  
Author(s):  
Hoejeong Jeong ◽  
Jae-Hyun Ryu ◽  
Sang-il Na ◽  
Jaeil Cho
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Thermal Image ◽  
Crop Growth ◽  
Leaf Temperature ◽  
Stress Index ◽  
Crop Water ◽  
Crop Water Stress Index ◽  
Water Stress Index ◽  
Crop Water Stress

<p>  In 1980s, Crop Water Stress Index (CWSI) is suggested to indicate the water stress of crops. CWSI is based on the leaf energy balance, which is closely related to leaf temperature. To calculate CWSI, meteorological factors such as air temperature and vapor pressure deficit should be measured besides leaf temperature. As recent technology has been developed, leaf temperature can be easily observed by thermal camera or infrared thermometer. Stomatal conductance (g<sub>s</sub>, mmol m<sup>-2</sup> s<sup>-1</sup>) is one of the critical factors to understand crop photosynthesis and water demand. In addition, the behaviors of g<sub>s</sub> can represent the biotic and abiotic plant stresses. In abnormal condition, such as drought, insects or disease, g<sub>s</sub> getting lower. The observation of g<sub>s</sub> will make better to evaluate and predict crop growth and conditions. Therefore, the time series data of g<sub>s</sub> is useful for the monitoring of crop growth and the quick detection of abnormal crop condition in smart-farming system but there are some limitations to measure g<sub>s</sub> continuously and easily.</p><p>  We assume that there is some relationship between CWSI and g<sub>s</sub> because both has strong relation to leaf temperature. Thus, the aim of this study is to investigate possibility of estimation of g<sub>s</sub> using CWSI which is derived from thermal image. Through the data collected from literatures, negative correlations between CWSI and g<sub>s</sub> were revealed. The slope of correlation was changed according to crop types. In addition, as a result of simulation, there is almost linear negative relationship between CWSI and g<sub>s</sub>, and the slope was determined by maximum stomatal conductance (g<sub>s_max</sub>). Field measurement in this study was also demonstrated to identify such correlation. Further, various methods to measure CWSI were tested. This relationship will contribute to not only monitoring of crop stress for irrigation scheduling in smart farm system but also estimating evapotranspiration, photosynthesis, and crop yield.</p>

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

Horticulturae ◽  
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.

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.

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