scholarly journals Rapid Equilibration of Leaf and Stem Water Potential under Field Conditions in Almonds, Walnuts, and Prunes

2001 ◽  
Vol 11 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Allan Fulton ◽  
Richard Buchner ◽  
Cyndi Gilles ◽  
Bill Olson ◽  
Nick Bertagna ◽  
...  
Keyword(s):  
Sample Size ◽  
Water Potential ◽  
Water Status ◽  
Irrigation Management ◽  
Irrigation Scheduling ◽  
Field Conditions ◽  
Equilibration Time ◽  
Diurnal Changes ◽  
Stem Water Potential ◽  
Stem Water

Covering a plant leaf with a reflective, water impervious bag ensures that equilibrium is reached between the nontranspiring leaf and the stem, and appears to improve the accuracy of determining plant water status under field conditions. However, the inconvenience of covering the leaf for 1 to 2 hours before measuring stem water potential (SWP) has constrained on-farm adoption of this irrigation management technique. A second constraint has been that the requirement of midafternoon determinations limits the area that can be monitored by one person with a pressure chamber. This paper reports findings from field studies in almonds (Prunus dulcis),prunes (P. domestica), and walnuts (Juglans regia) demonstrating modified procedures to measure midday SWP, making it a more convenient and practical tool for irrigation management. For routine monitoring and irrigation scheduling, an equilibration period of 10 min or longer appears to be suitable to provide accurate SWP measurements. Based on the large sample sizes in this study, we estimate that measurement error related to equilibration time for SWP can be reduced to an acceptable level [0.05 MPa (0.5 bar)] with a sample size of about 10 leaves when using a 10-min equilibration period. Under orchard conditions where tree growth and health appears uniform, a sample of one leaf per tree and 10 trees per irrigation management unit should give an accurate mean indicator of orchard water status. Under more variable orchard conditions a larger sample size may be needed. Midmorning and midday SWP both exhibited similar seasonal patterns and responded alike to irrigation events. On some occasions, midday SWP was accurately predicted from midmorning SWP and the change in air vapor pressure deficit (VPD) from midmorning to midday, but both over- and underestimate errors [to 0.3 MPa (3.0 bar)] appeared to be associated with unusually low or high diurnal changes in VPD, respectively. Hence, direct measurement of SWP under midday conditions (about 1300 to 1500 hr) is still recommended.

Does predawn water potential discern between irrigation treatments in Galician white grapevine cultivars?

OENO One ◽  
2014 ◽  
Vol 48 (2) ◽  
pp. 123 ◽  
Author(s):  
José Manuel Mirás-Avalos ◽  
Emiliano Trigo-Córdoba ◽  
Yolanda Bouzas-Cid
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Water Status ◽  
Irrigation Management ◽  
Growing Season ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Diurnal Changes ◽  
Stem Water Potential ◽  
Stem Water

<p style="text-align: justify;"><strong>Aims</strong>: To evaluate the usefulness of predawn water potential (<strong>Ψ</strong><sub>pd</sub>) to assess the water status of Galician grapevine cultivars for irrigation purposes.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Three Galician white grapevine cultivars (Albariño, Godello and Treixadura) were subjected to rain-fed and irrigation conditions during the 2013 growing season. Diurnal changes in leaf water potential (<strong>Ψ</strong><sub>l</sub>) were measured using a pressure chamber on days with high evapotranspiration demand. Stem water potential (<strong>Ψ</strong><sub>s</sub>) was measured at midday. <strong>Ψ</strong><sub>pd</sub> was not able to discriminate between treatments, whereas <strong>Ψ</strong><sub>l</sub> and <strong>Ψ</strong><sub>s</sub> at midday were able to detect significant differences in water status among plants.</p><p style="text-align: justify;"><strong>Conclusion</strong>: <strong>Ψ</strong><sub>pd</sub> was not useful to evaluate vine water status under the Galician climatic conditions. In contrast, both <strong>Ψ</strong><sub>l</sub> and <strong>Ψ</strong><sub>s</sub> were effective for detecting differences between treatments and can thus be used for irrigation management purposes.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This is the first study evaluating water status of Galician grapevine cultivars. It also provides useful information about the strategy for its control through measurements of midday <strong>Ψ</strong>l or <strong>Ψ</strong>s.</p>

scholarly journals 593 A Lightweight, Hand-operated Pressure Chamber for Determining Plant Water Status

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 499B-499
Author(s):  
Ken Shackel ◽  
David Paige
Keyword(s):  
Water Potential ◽  
Water Status ◽  
Irrigation Management ◽  
Nitrogen Pressure ◽  
Irrigation Scheduling ◽  
Pressure Chamber ◽  
Plant Water ◽  
Stem Water Potential ◽  
Stem Water ◽  
Time Required

In a number of tree crops, we have found that the water potential of lower canopy, nontranspiring leaves, measured with the pressure chamber at midday (midday stem water potential), is an excellent index of plant water stress and can be used for irrigation scheduling. Because stem water potential is typically much higher than transpiring leaf water potential, a lower pressure is required for the measurement, allowing us to design and build a lightweight device that could be easily operated by hand. The prototype was designed for pressures up to 2 MPa, which is sufficient for most irrigation conditions. A number of design features were incorporated into the sealing gland to eliminate the need for retightening during the pressurization process, reduce the amount of tissue external to the pressure chamber, and allow a greater visibility of the petiole. Identical values to those obtained with the standard, compressed nitrogen pressure chamber were obtained over the entire 2-MPa range, and the time required using either device under field conditions was the same (about 1 min per measurement). A number of alternative protocols were tested, and we found that even substantial recutting of the petiole had no influence on the measured water potential, contrary to popular belief. We also found that the same sample could be remeasured multiple times (five), with no net change in the water potential, allowing the measurement to be checked if necessary. This device should be of great utility in field irrigation management.

scholarly journals Midday Stem Water Potential Values Needed to Maintain Photosynthesis and Leaf Gas Exchange Established for Pecan

2014 ◽  
Vol 139 (5) ◽  
pp. 537-546 ◽  
Author(s):  
Yahia Othman ◽  
Dawn VanLeeuwen ◽  
Richard Heerema ◽  
Rolston St. Hilaire
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Stem Water Potential ◽  
Flood Irrigation ◽  
Dry Down ◽  
Stem Water ◽  
The Impact

Demand for New Mexico’s limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (Pn), and gas exchange [stomatal conductance (gS) to H2O (gH2O), transpiration (E), and intercellular CO2 (ci)] and to establish values of midday stem water potential (Ψsmd) that are needed to maintain Pn and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and Pn, gH2O, E, and ci were assessed at Ψsmd of –0.4 to –2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in Pn was markedly noticeable when Ψsmd dropped below –0.9 MPa. We attributed the reduction in Pn mostly to stomatal limitation. The decline in Pn and gH2O exceeded 50% when Ψsmd ranged from –1.5 to –2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at Ψsmd higher than –0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.

scholarly journals Impacts of water stress, environment and rootstock on the diurnal behaviour of stem water potential and leaf conductance in pistachio (Pistacia vera L.)

2016 ◽  
Vol 14 (2) ◽  
pp. e0804 ◽  
Author(s):  
Houssem Memmi ◽  
Jose F. Couceiro ◽  
Carmen Gijón ◽  
David Pérez-López
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Leaf Conductance ◽  
Irrigation Season ◽  
Stem Water Potential ◽  
Stem Water ◽  
Diurnal Behaviour ◽  
Pistachio Trees

Little information is available on the diurnal behaviour of water potential and leaf conductance on pistachio trees despite their relevance to fine tune irrigation strategies. Mature pistachio trees were subject to simultaneous measurements of stem water potential (Ψx) and leaf conductance (gl) during the day, at three important periods of the irrigation season. Trees were grown on three different rootstocks and water regimes. An initial baseline relating Ψx to air vapor pressure deficit (VPD) is presented for irrigation scheduling in pistachio. Ψx was closely correlated with VPD but with a different fit according to the degree of water stress. No evidence of the variation of Ψx in relation to the phenology of the tree was observed. Furthermore, midday Ψx showed more accuracy to indicate a situation of water stress than predawn water potential. Under well irrigated conditions, gl was positively correlated with VPD during stage II of growth reaching its peak when VPD reached its maximum value (around 4 kPa). This behaviour changed during stage III of fruit growth suggesting a reliance of stomatal behaviour to the phenological stage independently to the tree water status. The levels of water stress reached were translated in a slow recovery of tree water status and leaf conductance (more than 40 days). Regarding rootstocks, P. integerrima showed little adaptation to water shortage compared to the two other rootstocks under the studied conditions.

scholarly journals Towards Vine Water Status Monitoring on a Large Scale Using Sentinel-2 Images

2021 ◽  
Vol 13 (9) ◽  
pp. 1837
Author(s):  
Eve Laroche-Pinel ◽  
Sylvie Duthoit ◽  
Mohanad Albughdadi ◽  
Anne D. Costard ◽  
Jacques Rousseau ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Potential ◽  
Large Scale ◽  
Water Status ◽  
Vegetation Indices ◽  
Machine Learning Algorithms ◽  
Severe Drought ◽  
Stem Water Potential ◽  
Stem Water ◽  
Sentinel 2

Wine growing needs to adapt to confront climate change. In fact, the lack of water becomes more and more important in many regions. Whereas vineyards have been located in dry areas for decades, so they need special resilient varieties and/or a sufficient water supply at key development stages in case of severe drought. With climate change and the decrease of water availability, some vineyard regions face difficulties because of unsuitable variety, wrong vine management or due to the limited water access. Decision support tools are therefore required to optimize water use or to adapt agronomic practices. This study aimed at monitoring vine water status at a large scale with Sentinel-2 images. The goal was to provide a solution that would give spatialized and temporal information throughout the season on the water status of the vines. For this purpose, thirty six plots were monitored in total over three years (2018, 2019 and 2020). Vine water status was measured with stem water potential in field measurements from pea size to ripening stage. Simultaneously Sentinel-2 images were downloaded and processed to extract band reflectance values and compute vegetation indices. In our study, we tested five supervised regression machine learning algorithms to find possible relationships between stem water potential and data acquired from Sentinel-2 images (bands reflectance values and vegetation indices). Regression model using Red, NIR, Red-Edge and SWIR bands gave promising result to predict stem water potential (R2=0.40, RMSE=0.26).

Estimation water status of the vineyard by calculating multispectral index from satellite images

2021 ◽  
Author(s):  
Marta Rodríguez-Fernández ◽  
María Fandiño ◽  
Xesús Pablo González ◽  
Javier J. Cancela
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Spectral Index ◽  
Satellite Images ◽  
Irrigation System ◽  
Water Status ◽  
Stress Index ◽  
Stem Water Potential ◽  
Stem Water ◽  
Water Potential Measurements

&lt;p&gt;The estimation of the water status in the vineyard, is a very important factor, in which every day the winegrowers show more interest since it directly affects the quality and production in the vineyards. The situation generated by COVID-19 in viticulture, adds importance to tools that provide information of the hydric status of vineyard plants in a telematic way.&lt;/p&gt;&lt;p&gt;In the present study, the stem water potential in the 2018 and 2019 seasons, is analysed in a vineyard belonging to the Rias Baixas wine-growing area (Vilagarcia de Arousa, Spain), with 32 sampling points distributed throughout the plot, which allows the contrast and validation with the remote sensing methodology to estimate the water status of the vineyard using satellite images.&lt;/p&gt;&lt;p&gt;The satellite images have been downloaded from the Sentinel-2 satellite, on the closets available dates regarding the stem water potential measurements, carried out in the months of June to September, because this dates are considered the months in which vine plants have higher water requirements.&lt;/p&gt;&lt;p&gt;With satellite images, two spectral index related to the detection of water stress have been calculated: NDWI (Normalized Difference Water Index) and MSI (Moisture Stress Index). Stem water potential measurements, have allowed a linear regression with both index, to validate the use of these multispectral index to determine water stress in the vineyard.&lt;/p&gt;&lt;p&gt;Determination coefficients of r&lt;sup&gt;2&lt;/sup&gt;=0.62 and 0.67, have been obtained in July and August 2018 and 0.54 in June of 2019 for the NDWI index, as well as values of 0.53 and 0.63 in July 2018 and June 2019 respectively, when it has been analysed the MSI index.&lt;/p&gt;&lt;p&gt;Between both seasons, the difference observed, that implies slightly greater water stress in 2019, is reflected in the climate conditions during the summer months, with an average accumulated rainfall that doesn&amp;#8217;t exceed 46 mm of water. Although, the NDWI index has allowed to establish better relationships in the 2018 season respect to the MSI index and the 2019 season, (r&lt;sup&gt;2&lt;/sup&gt;=0.60 NDWI in 2018), as well as greater differences in terms of water stress presented in the vineyard.&lt;/p&gt;&lt;p&gt;With the spectral index calculated, it has been possible to validate the use of these index for the determination of the water stress of the vineyard plants, as an efficient, fast and less expensive method, which allows the application of an efficient irrigation system in the vineyard.&lt;/p&gt;

scholarly journals Microtensiometers Accurately Measure Stem Water Potential in Woody Perennials

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2780
Author(s):  
Victor Blanco ◽  
Lee Kalcsits
Keyword(s):  
Water Potential ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Full Range ◽  
Canopy Temperature ◽  
Plant Water ◽  
Stem Water Potential ◽  
Woody Tissue ◽  
Woody Perennials ◽  
Stem Water

Stem water potential (Ψstem) is considered to be the standard measure of plant water status. However, it is measured with the pressure chamber (PC), an equipment that can neither provide continuous information nor be automated, limiting its use. Recent developments of microtensiometers (MT; FloraPulse sensors), which can continuously measure water tension in woody tissue of the trunk of the tree, can potentially highlight the dynamic nature of plant water relations. Thus, this study aimed to validate and assess the usefulness of the MT by comparing the Ψstem provided by MT with those same measurements from the PC. Here, two irrigation treatments (a control and a deficit treatment) were applied in a pear (Pyrus communis L.) orchard in Washington State (USA) to capture the full range of water potentials in this environment. Discrete measurements of leaf gas exchange, canopy temperature and Ψstem measured with PC and MT were made every two hours for four days from dawn to sunset. There were strong linear relationships between the Ψstem-MT and Ψstem-PC (R2 > 0.8) and with vapor pressure deficit (R2 > 0.7). However, Ψstem-MT was more variable and lower than Ψstem-PC when Ψstem-MT was below −1.5 MPa, especially during the evening. Minimum Ψstem-MT occurred later in the afternoon compared to Ψstem-PC. Ψstem showed similar sensitivity and coefficients of variation for both PC and MT acquired data. Overall, the promising results achieved indicated the potential for MT to be used to continuously assess tree water status.

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