Predawn plant water potential does not necessarily equilibrate with soil water potential under well-watered conditions

Oecologia ◽  
2001 ◽  
Vol 129 (3) ◽  
pp. 328-335 ◽  
Author(s):  
L. Donovan ◽  
M. Linton ◽  
J. Richards
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Plant Water ◽  
Plant Water Potential

Water relations of winter wheat. 5. The root system and osmotic adjustment in relation to crop evaporation

1984 ◽  
Vol 102 (2) ◽  
pp. 415-425 ◽  
Author(s):  
M. McGowan ◽  
P. Blanch ◽  
P. J. Gregory ◽  
D. Haycock
Keyword(s):  
Winter Wheat ◽  
Water Potential ◽  
Root System ◽  
Soil Water ◽  
Osmotic Adjustment ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Plant Water ◽  
Potential Evaporation ◽  
Plant Water Potential

SummaryShoot and root growth and associated leaf and soil water potential relations were compared in three consecutive crops of winter wheat grown in the same field. Despite a profuse root system the crop grown in the second drought year (1976) failed to dry the soil as throughly as the crops in 1975 and 1977. Measurements of plant water potential showed that the restricted utilization of soil water reserves by this crop was associated with failure to make any significant osmotic adjustment, leading to premature loss of leaf turgor and stomatal closure. The implications of these results for models to estimate actual crop evaporation from values of potential evaporation are discussed.

THE EFFECT OF WATER DEFICIT ON N2(C2H2) FIXATION BY WHITE BEAN AND SOYBEAN

1988 ◽  
Vol 68 (4) ◽  
pp. 957-967 ◽  
Author(s):  
D. L. SMITH ◽  
M. DIJAK ◽  
D. J. HUME
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Acetylene Reduction ◽  
Physiological Responses ◽  
Plant Water ◽  
Diffusive Resistance ◽  
Drought Conditions ◽  
Plant Water Potential ◽  
White Bean

White bean (Phaseolus vulgaris L.) is generally reported to fix less N than soybean (Glycine max Merrill [L.]). Recent work has shown that in soybean the onset of physiological responses that conserve plant and soil water occurs at greater water deficits than in some other legumes. Little is known about water use regulation in white bean. Research was conducted to compare the responses of these two species to water deficit, particularly its effects on N2 fixation, in both controlled environment and field conditions. In the growth room, plant water potential, leaf diffusive resistance, acetylene reduction and nodule mass per plant were measured for both species during progressive drought, and compared to watered controls. In the field, the leaf diffusive resistance of irrigated and unirrigated plants of both species was measured, as was the soil water potential in plots where these crops were grown. Under conditions of increasing water deficit white bean reacts to conserve plant and soil water sooner than soybean: closing its stomates earlier under drought conditions and maintaining higher plant water potentials. White bean acetylene reduction declined more rapidly over time and over plant water potential levels, but not over changes in leaf diffusive resistance, than that of soybean, as the droughting progressed. In the field, under drought conditions, white bean root nodules senesced, while soybean nodules did not, and white bean was observed to exhibit more parahelionasty than soybean. The onset of physiological responses that conserve plant and soil water occurred at lesser water deficits in white bean than soybean, and this was reflected in more extreme effects on N2 fixation by white bean.Key words: White bean, soybean, water deficit, acetylene reduction, nitrogen fixation, nodulation

Soil Moisture as Predictor of Plant Water Status

2021 ◽  
Vol 47 (3) ◽  
pp. 110-115
Author(s):  
Johannes Hertzler ◽  
Steffen Rust
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Status ◽  
Soil Water Potential ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Plant Water ◽  
Estimation Errors ◽  
Plant Available Water ◽  
The Relationship

Soil water potential can be used as a proxy for plant available water in irrigation scheduling. This study investigated the relationship between soil water potential and plant water status of pines (Pinus sylvestris L.) planted into two different substrates. Predawn leaf water potential as a well-established measure of the plant water status and soil water potential correlated very well. However, estimating the plant water status from individual sensor readings is subject to significant estimation errors. Furthermore, it was shown that heterogeneous soil/root ball combinations can lead to critical effects on the soil water balance, and that sensors installed outside of the root balls cannot estimate the plant water status without site-specific calibration.

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.

Location of hydraulic resistance in the soil–plant pathway in seedlings of Pinussylvestris L. grown in peat

1986 ◽  
Vol 16 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Göran Örlander ◽  
Karin Due
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Dry Weight ◽  
Membrane System ◽  
Point Of View ◽  
Plant Water ◽  
Water Conductance ◽  
Dry Conditions ◽  
Total Dry Weight

Seedlings of Pinussylvestris L. were grown in three different soil media: 100% peat, 40% silt–60% peat, and 60% silt–40% peat. The percentages refer to total dry weight. Needle conductance, needle water potential, and plant water conductance were measured at different levels of soil water potentials controlled with a semipermeable membrane system. Seedlings grown in the 60:40 silt–peat mixture had a plant water conductance at a soil water potential of −0.1 MPa 3 times that of seedlings grown in pure peat. In an experiment where the roots were dipped in a silt slurry before planting, it was found that the plant water conductance at low soil water potential (−0.1 MPa) increased more than 2 times compared with undipped controls. We concluded that an important resistance to water flow in the soil–plant pathway was located in the soil outside the roots and probably was the most important resistance in the root–soil interface. The use of low humified peat as a growth medium is open to discussion from a silvicultural point of view because of its hydraulic properties under dry conditions.

scholarly journals Comparison of Leaf and Stem Hygrometers for Measuring Changes in Peanut Plant Water Potential1

1978 ◽  
Vol 5 (2) ◽  
pp. 65-67 ◽  
Author(s):  
James E. Pallas ◽  
Burlyn E. Michel
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Movement ◽  
Plant Water ◽  
Dynamic Changes ◽  
Soil Water Stress ◽  
Arachis Hypogaea L ◽  
Plant Water Potential ◽  
Plant Process

Abstract For an “in situ” thermocouple hygrometer to be of value it must give reasonable estimates of plant-water potential and must respond rapidly to plant-water potential changes. Leaf thermocouple hygrometers (Wescor) and specially fabricated stem thermocouple hygrometers were evaluated on peanut (Arachis hypogaea L.) plants under well-watered and drought conditions in a growth chamber. When soil-water stress was low and plant-water movement was near steady state, the two sensors gave similar water potential values. When soil-water stresses were imposed or when plant process varied cyclically (eg., photosynthesis, transpiration), stem hygrometers sensed dynamic changes in the plant's water potential more consistently than did leaf hygrometers placed on leaves with intact cuticles. It appears that both the stem and leaf hygrometers hold promise for sensing plant water potential changes of peanut in the field.

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