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.

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

<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>Determination coefficients of r<sup>2</sup>=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.</p><p>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’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<sup>2</sup>=0.60 NDWI in 2018), as well as greater differences in terms of water stress presented in the vineyard.</p><p>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.</p>

Multispectral reflectance vegetation indices are highly sensitive to water stress in grapefruit trees

2020 ◽  
Author(s):  
Pablo Berrios ◽  
Abdelmalek Temnani ◽  
David Pérez ◽  
Ismael Gil ◽  
Susana Zapata ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Vegetation Index ◽  
Pearson Correlation ◽  
Vegetation Indices ◽  
Irrigation Scheduling ◽  
Plant Water ◽  
Citrus Paradisi ◽  
Stem Water Potential ◽  
Stem Water

<p>The sensitivity to water stress of different plant water indicators (PWI) at different plot scales (leaf and aerial) was evaluated during the second fruit growth stage of grapefruit (<em>Citrus paradisi</em> cv. Star Ruby) trees growing in a commercial orchard for a sustainable irrigation scheduling. Trees were drip-irrigated and submitted to two irrigation treatments: (i) a control (CTL), irrigated at 100% of crop evapotranspiration to avoid any soil water limitations, and (ii) a non-irrigated (NI) treatment, irrigated as the control until the 104 days after full bloom (DAFB) when the irrigation was suppressed, until to reach a severe water stress level in the plants (around -2.3 MPa of stem water potential at solar midday). The plant water indicators studied were: stem water potential (SWP); leaf conductance (Lc); net photosynthesis (Pn), and several vegetation indices (VI) in the visible spectral region derived from an unmanned aerial vehicle equipped with a multispectral sensor. The measurements were made at 9, 12 and 18h (solar time) on 50 and 134 DAFB, coinciding with a fruit diameter of 20 and 70 mm, respectively. The correlation analysis between the PWI at leaf scale (SWP, Lc and Pn) and at aerial scale showed relatively poor results, with Pearson correlation coefficients (r values) around 0.6. However, SWP presented the highest r value with the normalized difference vegetation index (NVDI), green index (GI), normalized difference greenness vegetation index (NDGI) and red green ratio index (RGRI) showing the higher coefficients 0.80, 0,80, 0.85 and 0.86, respectively. In addition, a quadratic regression curve fitting was made for the SWP and aforementioned indices, obtaining values ​​of R<sup>2</sup> around 0.7 in all cases; the best fit corresponded to SWP = - 4.869 + 15.765 NDGI - 14.283 NDGI<sup>2</sup> (R<sup>2 </sup>= 0.749) to predict SWP values between -0.5 and -2.3 MPa. Results obtained show the possibility of using certain vegetation indices to be used in the detection of water stress in adult grapefruits, and thus propose a sustainable and efficient irrigation scheduling.</p><p>Funding:</p><p>-WATER4EVER is funded by the European Commission under the framework of the ERA-NET COFUND WATERWORKS 2015 Programme</p><p>-RIS3MUR REUSAGUA is funded by the Consejería de Empresa, Industria y Portavocía of the Murcia Region under the Feder Operational Program 2014-2020</p>

Water stress and reduced fruit size in micro-irrigated pear trees under deficit partial rootzone drying

2007 ◽  
Vol 58 (7) ◽  
pp. 670 ◽  
Author(s):  
Mark G. O'Connell ◽  
Ian Goodwin
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Fruit Size ◽  
Leaf Conductance ◽  
Stem Water Potential ◽  
Crop Water ◽  
Reproductive Growth ◽  
Stem Water ◽  
Partial Rootzone Drying

Crop water relations, vegetative and reproductive growth, and soil water status were studied during 2 seasons to determine the effectiveness of partial rootzone drying (PRD) in a mature micro-irrigated pear orchard in the Goulburn Valley, Australia. PRD treatments were 50% (PRD50) and 100% (PRD100) of predicted crop water requirement (ETc) applied on one side of the tree alternated on a 14-day cycle compared with a Control treatment, which received 100% of ETc irrigated on both sides of the tree. Irrigation was applied daily by micro-jets to replace ETc estimated using reference crop evapotranspiration (ETo) and a FAO-56 crop coefficient of 1.15 adjusted for tree size. The PRD50 regime applied 174–250 mm for the season v. 347–470 mm for both the Control and PRD100 treatments. Irrigation maintained a well watered rootzone under the emitter compared with the drying profiles of the alternated wet/dry irrigated zones of the PRD treatments. There was no significant benefit of PRD100 compared with the Control irrigation regime. Similar vegetative growth (canopy radiation interception), reproductive growth (fruit growth rate, final fruit size, yield), fruit quality (total soluble solids, flesh firmness), and crop water relations (midday leaf conductance, midday leaf and stem water potential) were measured between the Control and PRD100. Trees under the PRD50 regime showed symptoms of severe water stress, that being greater fruit drop, reduced fruit size, lower yield, reduced leaf conductance, and lower leaf and stem water potential. The 50% water saving afforded by PRD50 led to a yield penalty of 16–28% compared with the Control and PRD100. PRD50 fruit failed to meet commercial cannery requirements due to poor fruit size. We conclude from an agronomic basis that deficit PRD irrigation management is not recommended for micro-irrigated pear orchards on fine-textured soils in the Goulburn Valley, Australia.

scholarly journals Effect of Fall Irrigation Level in `Mauritius' and `Floridian' Lychee on Soil and Plant Water Status, Flowering Intensity, and Yield

1998 ◽  
Vol 123 (1) ◽  
pp. 150-155 ◽  
Author(s):  
R.A. Stern ◽  
M. Meron ◽  
A. Naor ◽  
R. Wallach ◽  
B. Bravdo ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Shoot Growth ◽  
Water Status ◽  
Plant Water ◽  
Stem Water Potential ◽  
Irrigation Level ◽  
Irrigation Control ◽  
Stem Water ◽  
Flowering Intensity

The effect of fall irrigation level in `Mauritius' and `Floridian' lychee (Litchi chinensis Sonn.) on soil and plant water status, flowering intensity, and yield the following year was studied in a field during 2 consecutive years. At the end of the second vegetative flush after harvest (1 Oct. 1994 and 10 Oct. 1995), four irrigation treatments were initiated: 0.5, 0.25, 0.125, and 0 Class A pan evaporation coefficients designated 100%, 50%, 25%, and 0%. The three lower irrigation levels effectively stopped shoot growth, suggesting the 50% treatment to be the threshold for shoot growth cessation in both years. For both years, flowering intensity and yield in the 100% treatment were lower than those following the other three treatments. Soil and plant water-stress indicators responded to the water-stress irrigation treatments. However soil water-potential values were highly variable relative to plant water potentials. Stem water potential differed more markedly between treatments than leaf water potential. Midday stem water potential appeared to be the best water-stress indicator for irrigation control. Midday stem water potential in both years was correlated with midday vapor-pressure deficit, suggesting that the threshold for irrigation control should take into account evaporative demand.

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 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.

scholarly journals Performance Assessment of Thermal Infrared Cameras of Different Resolutions to Estimate Tree Water Status from Two Cherry Cultivars: An Alternative to Midday Stem Water Potential and Stomatal Conductance

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3596 ◽  
Author(s):  
Marcos Carrasco-Benavides ◽  
Javiera Antunez-Quilobrán ◽  
Antonella Baffico-Hernández ◽  
Carlos Ávila-Sánchez ◽  
Samuel Ortega-Farías ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Prunus Avium ◽  
Water Status ◽  
Thermal Infrared ◽  
Stem Water Potential ◽  
Cherry Tree ◽  
Stem Water ◽  
Irrigation Treatments

The midday stem water potential (Ψs) and stomatal conductance (gs) have been traditionally used to monitor the water status of cherry trees (Prunus avium L.). Due to the complexity of direct measurement, the use of infrared thermography has been proposed as an alternative. This study compares Ψs and gs against crop water stress indexes (CWSI) calculated from thermal infrared (TIR) data from high-resolution (HR) and low-resolution (LR) cameras for two cherry tree cultivars: ‘Regina’ and ‘Sweetheart’. For this purpose, a water stress–recovery cycle experiment was carried out at the post-harvest period in a commercial drip-irrigated cherry tree orchard under three irrigation treatments based on Ψs levels. The water status of trees was measured weekly using Ψs, gs, and compared to CWSIs, computed from both thermal cameras. Results showed that the accuracy in the estimation of CWSIs was not statistically significant when comparing both cameras for the representation of Ψs and gs in both cultivars. The performance of all evaluated physiological indicators presented similar trends for both cultivars, and the averaged differences between CWSI’s from both cameras were 11 ± 0.27%. However, these CWSI’s were not able to detect differences among irrigation treatments as compared to Ψs and gs.

scholarly journals Relationship of stem water potential and leaf conductance to vegetative growth of young olive trees in a hedgerow orchard

2008 ◽  
Vol 59 (3) ◽  
pp. 270 ◽  
Author(s):  
María Gómez-del-Campo ◽  
A. Leal ◽  
C. Pezuela
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Vegetative Growth ◽  
Shoot Growth ◽  
Irrigation Treatment ◽  
Leaf Conductance ◽  
Stem Water Potential ◽  
Trunk Diameter ◽  
Stem Water

In 2005, four irrigation treatments were applied to a 3-year-old cv. Cornicabra orchard. In T1, wetted soil volume was maintained close to field capacity by irrigating when soil sensors indicated that soil water potential in the root zone had fallen to –0.03 MPa and 0.06 MPa from spring until 15 August and from 15 August until September, respectively. On those days, 8, 6, 4, and 2 h of irrigation was applied to T1, T2, T3, and T4, so that over the season they received 106, 81, 76 and 31 mm of irrigation, respectively. The high value for T3 was the result of a valve failure on 13 June. Measurements were maintained throughout the experimental period of relative extractable water (REW) to 1 m depth at the wetted volume (0.30 m from a drip emitter), shoot length, trunk diameter, stem water potential (Ψstem) and leaf conductance (gl). The irrigation treatment significantly affected REW (P < 0.10), Ψstem, gl and vegetative growth (P < 0.05). Ψstem, and trunk diameter were the least variable parameters and Ψstem and shoot growth were the most sensitive to water stress. Although T1 received 24% more water than T2, no significant differences were detected in vegetative growth. T2 should be considered the optimum irrigation value. The mean monthly Kc for T2 was 0.086. The failure of the valve in T3 simulated a wet spring followed by limited irrigation. Irrigation applied was similar to T2 but shoot growth stopped one month earlier and lower values of Ψstem and gl were observed after mid August. REW was highly related to vegetative growth, 66% of maximum being achieved at REW 0.53 and 50% at 0.45. gl was independant of plant or soil water status and did not determine vegetative growth. A strong relationship established Ψstem as a good indicator of vegetative growth and hence of water stress. Shoot growth was 66% of maximum at Ψstem –1.5 MPa and 50% at –1.8 MPa.

scholarly journals Irrigation Water Management for Pecans in Humid Climates

HortScience ◽  
2015 ◽  
Vol 50 (7) ◽  
pp. 1070-1074 ◽  
Author(s):  
Lenny Wells
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Water Potential ◽  
Irrigation Water ◽  
Irrigation Schedule ◽  
Irrigation Scheduling ◽  
Stem Water Potential ◽  
Crop Load ◽  
Early Season ◽  
Stem Water

Pecan [Carya illinoinensis (Wangenh.) K. Koch] tree stem water potential (ψ), shoot length, nut yield, and nut quality for the following treatments were evaluated in a commercial pecan orchard in Berrien County, GA; 1) current recommended irrigation schedule, 2) a reduced early season irrigation schedule, and 3) non-irrigated control. Water Stress on pecan occurred at ≈−0.78 MPa using the pressure chamber to measure stem water potential. Regression analysis suggests that irrigation scheduling for mature pecan trees may be needed when volumetric water content reaches 10% on Tifton loamy sand soil. Water stress in pecan is correlated with soil moisture from budbreak through the end of nut sizing. Pecan trees bearing a moderate to heavy crop load may undergo water stress during the kernel-filling stage regardless of soil moisture level. Therefore, it is suggested that water stress during the kernel-filling period is a function of nut development, crop load, or both in addition to soil moisture. The reduced early season irrigation schedule provided a 38% reduction in irrigation water use with no significant effect on pecan tree water stress, yield, or quality, suggesting that pecan trees can tolerate moderate early season water stress with no effect on pecan yield or quality under southeastern U.S. environmental conditions.

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