scholarly journals Simulating nectarine tree transpiration and dynamic water storage from responses of leaf conductance to light and sap flow to stem water potential and vapor pressure deficit

2015 ◽  
Vol 35 (4) ◽  
pp. 425-438 ◽  
Author(s):  
I. Paudel ◽  
A. Naor ◽  
Y. Gal ◽  
S. Cohen
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Water Storage ◽  
Leaf Conductance ◽  
Stem Water Potential ◽  
Tree Transpiration ◽  
Stem Water

Relationships Between Climatic Variables and Sap Flow, Stem Water Potential and Maximum Daily Trunk Shrinkage in Lemon Trees

2006 ◽  
Vol 279 (1-2) ◽  
pp. 229-242 ◽  
Author(s):  
M. F. Ortuño ◽  
Y. García-Orellana ◽  
W. Conejero ◽  
M. C. Ruiz-Sánchez ◽  
O. Mounzer ◽  
...  
Keyword(s):  
Water Potential ◽  
Sap Flow ◽  
Climatic Variables ◽  
Stem Water Potential ◽  
Stem Water

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.

Assessing reliability of HRM sap-flow sensors under large range of vapor pressure deficit

2020 ◽  
Author(s):  
Rémy Schoppach ◽  
Daniella Ekwalla Hangue ◽  
Julian Klaus
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Heat Waves ◽  
Linear Trend ◽  
Water Flux ◽  
Gravimetric Method ◽  
Flow Sensors ◽  
Tree Transpiration ◽  
Sap Flow Sensors

<p>Evapotranspiration (ET) is a major water flux of ecosystems and represents globally 60-80% of the incoming precipitation lost by terrestrial environments. In forested lands, tree transpiration (TR) is the dominant component of ET, yet remains challenging to measure. Over the years, sap-flow sensors have become the standard tool for quantifying tree TR and different methods based on thermal approaches have been developed. Heat ratio methods (HRM) are considered as the most reliable and accurate method to quantify absolute flows. Leading commercial brands ensure an accurate measurement of positive flows up to 100 cm hr<sup>-1</sup> but different studies have highlighted a saturation effect at high flows with threshold for accuracy remaining elusive[RS1] . Due to climate change, the occurrence, the severity and the duration of extreme events like heat waves and dry periods are expected to increase in future, so the potential for high TR rate periods will also increase. Therefore, it is crucial to determine the species-specific environmental conditions allowing a reliable measurement of TR in order to improve or understanding of eco-hydrological and physiological processes during high potential TR periods that can be crucial for vegetation survival. In this study, we tested the accuracy of HRM sap-flow sensors for beech (Fagus sylvatica) and oak (Quercus robur) tree species under extreme vapor pressure deficit (VPD) conditions in order to determine threshold for reliable measurements. In greenhouse conditions, we collected a complete and dense series of TR response to VPD between 0.7 to 8.3 kPa for potted beech and oak trees using three different methods: infrared gas analyser, gravimetric method, and HRM sap-flow sensors. Responses shown a linear trend at the low-canopy leaf level (41.5 and 45.1 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> respectively for beech and oak) but a bi-linear conformation at the whole plant level (1<sup>st</sup> slope = 12.04 ± 0.7 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> and break-point at 3.9 ± 0.07 kPa for beech trees). Sap-flow sensors using the HRM method displayed a clear inability to reliably measure flows under high VPD conditions. Thresholds of 2.25 ± 0.04 and 2.87 ± 0.14 kPa were identified as the maximum limit of method reliability for beech and oak respectively. In highly demanding environments, we suggest a bi-linear extrapolation beyond VPD threshold for better quantifying tree TR. Further experiments aiming at characterizing TR responses to VPD for a broad range of species and in different water deficit conditions are certainly needed for better understanding tree transpiration at the whole stand level.</p>

Examination and parameterization of the root water uptake model from stem water potential and sap flow measurements

2012 ◽  
pp. n/a-n/a ◽  
Author(s):  
Yuting Yang ◽  
Huade Guan ◽  
John L. Hutson ◽  
Hailong Wang ◽  
Caecilia Ewenz ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Uptake ◽  
Sap Flow ◽  
Root Water Uptake ◽  
Stem Water Potential ◽  
Flow Measurements ◽  
Stem Water ◽  
Sap Flow Measurements

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 Effect of canopy management in the water status of cacao (Theobroma cacao) and the microclimate within the crop area

2019 ◽  
Vol 97 (4) ◽  
pp. 701-710
Author(s):  
Alfredo Jiménez-Pérez ◽  
Manuel J. Cach-Pérez ◽  
Mirna Valdez-Hernández ◽  
Edilia De la Rosa-Manzano
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Sap Flow ◽  
Theobroma Cacao ◽  
Vapor Pressure Deficit ◽  
Soil Water Potential ◽  
Flow Density ◽  
Closed Canopy ◽  
Sap Flow Density ◽  
Crop Area

Background: Cacao is an umbrophile species and therefore the handling of shade by producers can cause a microclimatic modification that influences the physiology of the plant. Questions: Can canopy management influence the microclimate of the crop area and the water content of cacao? Species of study: Theobroma cacao L. (Malvaceae). Study site: Comalcalco, Tabasco, Mexico; dry and rainy season 2018. Methods: Three sites were selected with an open canopy (OC) and three with a closed canopy (CC), where we determined air temperature and humidity, soil temperature, vapor pressure deficit, photosynthetically active radiation, soil water potential and leaf water potential in 15 cacao trees and the sap flow density in 12 trees, by canopy condition and by season. Results: Higher values of solar radiation, air and soil temperature, vapor pressure deficit and lower relative humidity were recorded under OC compared to CC, in both seasons. Differences in soil water potential between 10 and 60 cm depth in CC were recorded during the dry season. There was a lower sap flow density and daily water use in OC. The leaf water potential was similar between canopy conditions, in both seasons. Conclusions: Changes in canopy coverage significantly modify the microclimate of the crop area, a less stressful environment being generated under closed canopy conditions, influencing the sap flow density of cacao trees.

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