Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1 ◽  
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

Corrigenda - Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

Correction

Soil Research ◽  
1993 ◽  
Vol 31 (2) ◽  
pp. 225
Author(s):  
IM Wood
Keyword(s):  
Polyethylene Glycol ◽  
Aqueous Solutions ◽  
Water Potential ◽  
Soil Cores ◽  
Total Water ◽  
Thermocouple Psychrometer

Measurement of the Total Water Potential of Aqueous-Solutions of Polyethylene-Glycol - a Comparison Between Osmometer, Thermocouple Psychrometer and Equilibrated Soil Cores (Vol 31, Pg 7, 1993)

Water potentials of seeds of Bromus inermis and Medicago sativa imbibed on media of various osmotic potentials

1976 ◽  
Vol 54 (17) ◽  
pp. 1997-1999 ◽  
Author(s):  
W. T. McDonough
Keyword(s):  
Polyethylene Glycol ◽  
Medicago Sativa ◽  
Bromus Inermis ◽  
Smooth Brome ◽  
Thermocouple Psychrometer ◽  
Water Potentials ◽  
The Media ◽  
Medicago Sativa L ◽  
Brome Grass ◽  
Osmotic Potentials

Seeds of smooth brome grass (Bromus inermis Leyss.) and alfalfa (Medicago sativa L. cultivar Ladak) were allowed to imbibe in water or solutions of polyethylene glycol (Carbowax 1540), mannitol, or sodium chloride. Seed water potentials were determined over a 72-h period after transfer of seeds to thermocouple psychrometer chambers. Seed water potentials were lower than osmotic potentials of the media, but these two potentials were not clearly related to each other. Possible reasons for the lack of gradation in response are discussed.

Evaporation from porous media as influenced by osmotic potential

2020 ◽  
Author(s):  
Adil Salman ◽  
Deep Joshi ◽  
Mahyar Naseri ◽  
Wolfgang Durner
Keyword(s):  
Porous Media ◽  
Water Potential ◽  
Osmotic Potential ◽  
Soil Surface ◽  
Natural Soil ◽  
Total Water ◽  
Matric Potential ◽  
Model Calculations ◽  
Two Stages ◽  
Saline Solutions

<p>The measurement of the water potential is important to characterize solute transport in soil and water uptake by plants. Many researchers have characterized the matric potential and its impact on evaporation from porous media. However, only few studies have been carried out to characterize the effect of the osmotic potential. In this study, we investigated the simultaneous influences of the osmotic and matric potentials on the evaporation from soil. Our hypothesis was that both potential components affect the two stages of evaporation and that the osmotic potential in direct vicinity of the soil surface is a controlling variable. To meet our objective, we performed evaporation experiments on columns filled with pure quartz sand and natural soil materials with different textures, under climate-controlled laboratory conditions. The soils were initially saturated with different concentrations of saline solutions and evaporation from each column was measured daily. Our results show that the osmotic potential reduced the amount of evaporated water from the investigated porous media. The amount of reduction due to the osmotic potential is compared with model calculations that consider the total water potential at the soil surface.</p>

Effects of water potential on germination of lettuce, sunflower, and citrus seeds

1969 ◽  
Vol 47 (11) ◽  
pp. 1761-1764 ◽  
Author(s):  
Merrill R. Kaufmann
Keyword(s):  
Polyethylene Glycol ◽  
Water Stress ◽  
Water Potential ◽  
Cellulose Acetate Membrane ◽  
Lettuce Seeds ◽  
Water Potentials ◽  
Citrus Seeds ◽  
Germinating Seeds ◽  
Polyethylene Glycol 6000 ◽  
Selection Of

The effect of nearly constant water potential on germination of citrus, sunflower, and lettuce seeds was studied. Water potential equilibration was achieved by placing soil above a cellulose acetate membrane which was in contact with a solution of polyethylene glycol-6000. Selection of solute potentials in the solution resulted in controlled water potentials in the soil over a range of 0 to −14.9 bars for citrus and 0 to −8.0 bars for sunflower and lettuce. The water stress experienced by germinating seeds in this system is largely the result of a matric effect rather than a solute effect.Citrus seeds germinated at water potentials as low as −4.7 bars and lettuce at −4.1 bars, but sunflower germinated at −8.0 bars. Sunflower germinated as rapidly at −4.1 bars as lettuce at −2.3 bars, both reaching 50% germination at about 8 days. Citrus germinated much more slowly, requiring 26 days at 0 bars.

scholarly journals Linear Relationship of a Soil Total Water Potential Function and Relative Yield—A Technique to Control Salinity and Water Stress on Golf Courses and Other Irrigated Fields

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1916
Author(s):  
Jose Beltrao ◽  
Gulom Bekmirzaev ◽  
Jiftah Ben Asher ◽  
Manuel Costa ◽  
Thomas Panagopoulos
Keyword(s):  
Water Potential ◽  
Crop Yields ◽  
Relative Yield ◽  
Golf Courses ◽  
Simple Relationship ◽  
Total Water ◽  
Trickle Irrigation ◽  
Matric Potential ◽  
Retention Model ◽  
Relationship Of

A simple empirical approach is proposed for the determination of crop relative yield (%) through the soil total water potential (kPa). Recurring to decimal logarithms, from analytical exponential expressions, a linear simple relationship of soil total water potential Ψt (matric Ψm + potential Ψo) function and crop relative yield was studied and developed. The combination of the salinity model, the soil water retention model and the matric potential approach were used to reach this objective. The representation of turfgrass crop relative yield (%) versus a function of soil total water potential f(Ψt) values was shown through a log-normal graph (y = a + mx); the log scale axis “y” (ordinates) defines relative yield Yr, being two the origin ordinate “a” and “m” the slope; the normal decimal scale axis “x” (abscissa) is the function of soil total water potential f(Ψt). Hence, it is possible, using only two experimental points, to define a simple linear relation between a function of soil total water potential and crop relative yield, for a soil matric potential value lower than −20 kPa. This approach was first tested on golf courses (perennial turfgrass fields), but it was further decided to extend it to other annual crop fields, focused on the model generalization. The experimental plots were established, respectively, in Algarve, Alentejo and Oeiras (Portugal) and in the North Negev (Israel). Sprinkler and trickle irrigation systems, under randomized blocks and/or water and salt gradient techniques, were used for water application with a precise irrigation water and salt distribution. Results indicated that there is a high agreement between the experimental and the prediction values (R2 = 0.92). Moreover, the precision of this very simple and easy tool applied to turfgrass fields and other irrigated soils, including their crop yields, under several different sites and climatic conditions, can contribute to its generalization.

MEASUREMENT OF INTERNAL WATER STRESS IN WHEAT PLANTS

1968 ◽  
Vol 48 (1) ◽  
pp. 89-95 ◽  
Author(s):  
S. J. Yang ◽  
E. de Jong
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Great Promise ◽  
Plant Water ◽  
Thermocouple Psychrometer ◽  
Water Potentials ◽  
Plant Water Potential ◽  
Highly Correlated ◽  
The Many ◽  
Non Destructive

The thermocouple psychrometer technique was used to measure plant water stresses of wheat. The usefulness of this technique is limited due to the many precautions that must be taken. The β-ray absorption and relative turgidity were highly correlated (P = 0.01) with plant water potential, but the correlation changed with age. Relative turgidity gave a slightly better estimate of leaf water potential than β-ray absorption (r2 of 0.88 to 0.99 and 0.81 to 0.96 respectively). The β-ray technique has great promise because of its non-destructive nature.At soil water potentials higher than −10 atm, plant water potentials remained nearly constant, indicating that soil water was equally available. Temporary wilting occurred at soil water potentials of −35 to −40 atm.

The importance of liquid-seed contact during the germination of Medicago tribuloides Desr.

1963 ◽  
Vol 14 (5) ◽  
pp. 646 ◽  
Author(s):  
RH Sedgley
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Liquid Water ◽  
Total Water ◽  
Matric Potential ◽  
Small Pressure ◽  
Plate Apparatus

At a given matric potential, rates of uptake of water and rates of seed germination on a suction plate apparatus were increased by improving the degree of contact between liquid water and seed. The conclusion of Collis-George and Sands (1962) that small matric potentials, as such, influence the rate of seed germination is critically reviewed in the light of the present investigation. The rate of germination of seeds was not influenced by small pressure potentials, which like matric potentials are a non-osmotic component of the total water potential.

A preliminary study of the influence of water potential on sclerotium germination in Sclerotinia sclerotiorum

1977 ◽  
Vol 55 (1) ◽  
pp. 8-11 ◽  
Author(s):  
R. A. A. Morrall
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Sclerotinia Sclerotiorum ◽  
Clay Soil ◽  
Semipermeable Membrane ◽  
Water Potentials ◽  
Heavy Clay ◽  
Influence Of Water ◽  
Preliminary Study

Sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary buried in a heavy clay soil at 15 °C germinated over a range of moisture levels from 15% to 50%. A method of germinating sclerotia held at constant matric water potentials was tested. Sclerotia were placed in soil in bags of a semipermeable membrane; the bags were immersed in solutions of polyethylene glycol 20 000.Germination occurred between 0 and −7.5 bars but not at lower potentials.

GERMINATION OF WHEAT AS AFFECTED BY SOIL WATER STRESS

1972 ◽  
Vol 52 (4) ◽  
pp. 619-623 ◽  
Author(s):  
M. C. PAWLOSKI ◽  
C. F. SHAYKEWICH
Keyword(s):  
Water Stress ◽  
Hydraulic Conductivity ◽  
Water Potential ◽  
Soil Water ◽  
Germination Rate ◽  
Membrane System ◽  
Semipermeable Membrane ◽  
Matric Potential ◽  
Soil Water Stress ◽  
Water Potentials

Germination rate of wheat was determined at several water potentials (−0.8, −5.3, −7.8, and −15.3 bars) on two soils and a semipermeable membrane. Germination rate decreased as matric potential decreased. At a given water potential, germination rates were the same for both soils but germination on the membrane system was faster than on soils. Hydraulic conductivity was different on the two media, indicating that the hydraulic conductivity is an important component of soil water stress. Germination rate was not affected by decreasing water potential to −7.8 bars on each medium. At the −15.3-bar potential germination rate was considerably slower.

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