Internal Water Balance of Brigalow (Acacia harpophylla F. Muell.) Under Natural Conditions

1975 ◽  
Vol 2 (4) ◽  
pp. 489 ◽  
Author(s):  
BR Tunstall ◽  
DJ Connor
Keyword(s):  
Water Potential ◽  
Water Status ◽  
Carbon Uptake ◽  
Diurnal Changes ◽  
Plant Water ◽  
Litter Fall ◽  
Tissue Water ◽  
Diffusive Resistance ◽  
Plant Water Potential ◽  
Water Contents

On one day each month over a period of 2½ years, diurnal measurements of plant water status, leaf diffusive resistance, carbon uptake, irradiance, ambient temperature and humidity were made in a brigalow community. Diurnal changes in leaf diffusive resistance, osmotic potential, plant water potential, and carbon uptake are shown to follow general patterns and the changes in plant water potential were related to the dawn value of plant water potential. The data suggest the development of negative turgor in brigalow and demonstrate the capacity of the plant to maintain high tissue water contents at low water potentials. Measurements of shoot extension and litter fall showed that litter fall occurred principally following shoot extension.

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

The influences of temperature and soil water on growth, photosynthesis, and nitrogen fixation of red alder (Alnusrubra) seedlings

1994 ◽  
Vol 24 (5) ◽  
pp. 1029-1032 ◽  
Author(s):  
B.J. Hawkins ◽  
S. McDonald
Keyword(s):  
Nitrogen Fixation ◽  
Water Potential ◽  
Soil Water ◽  
Water Status ◽  
Net Photosynthesis ◽  
Field Capacity ◽  
Plant Water ◽  
Red Alder ◽  
Plant Water Potential ◽  
The Difference

A 3 × 2 factorial experiment was conducted to investigate the interaction of temperature and soil water status on the growth, photosynthetic, transpiration, and nitrogen fixation rates of 2-month-old red alder (Alnusrubra Bong.) seedlings. Three day: night temperature treatments, 15:10 °C, 20:10 °C, and 25:10 °C were used. Two soil-water treatments kept pots between 85 and 100% of field capacity (wet) and 70–85% of field capacity (dry). Treatment effects on growth, net photosynthetic, transpiration and nitrogen fixation rates, plant water potential, and foliar nutrient concentration were measured over a 9-week period. The greatest seedling growth occurred at 25 °C day temperatures, while 20 and 25 °C days produced the greatest nodule growth. The allocation of biomass to roots increased with decreasing temperature. The highest rates of net photosynthesis occurred at 15 and 20 °C whereas transpiration was greatest at 25 °C. Plant water stress was greatest at 25 °C. The difference in plant water potential between the wet and dry treatments was only 0.04 MPa, which was not great enough to produce significant effects on growth or photosynthesis. Nitrogen fixation rates were highest in the wet treatment seedlings at 20 and 25 °C.

Branch water potential; a useful indicator of plant water potential in comparison to leaf water potential in canola

2000 ◽  
Vol 40 (5) ◽  
pp. 687 ◽  
Author(s):  
A. L. Bernardi
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Water Status ◽  
Source Material ◽  
Leaf Water ◽  
Moisture Loss ◽  
Plant Water ◽  
Portable Equipment ◽  
Plant Water Potential ◽  
Main Growth

The water potentials of canola branches and leaves were compared using a pressure chamber to determine whether they produced similar results. This study also investigated the magnitude of errors in the water status of canola resulting from re-cutting the branches, and the effects of delaying readings. The use of branches containing pods or pods and flowers/buds gave very good correlation with leaves. As this is the area of greatest photosynthesis and transpiration from mid-flowering, it provides an easily obtainable source material close to the main growth areas to measure plant water potential. Storage of both leaves and stems before measurement is an acceptable procedure if a large number of samples are required to be completed or portable equipment is not available provided precautions are taken to prevent moisture loss. Re-cutting the branch leads to lower water potential and should be avoided.

Diurnal Changes in Plant Water Potential and Canopy Temperature of Wheat as Affected by Drought 1

1978 ◽  
Vol 70 (6) ◽  
pp. 999-1004 ◽  
Author(s):  
W. L. Ehrler ◽  
S. B. Idso ◽  
R. D. Jackson ◽  
R. J. Reginato
Keyword(s):  
Water Potential ◽  
Canopy Temperature ◽  
Diurnal Changes ◽  
Plant Water ◽  
Plant Water Potential

scholarly journals Dynamic aspects of plant water potential revealed by a microtensiometer

2021 ◽  
Author(s):  
Vinay V Pagay
Keyword(s):  
Water Potential ◽  
Water Status ◽  
Vapour Pressure Deficit ◽  
Irrigation Scheduling ◽  
Field Conditions ◽  
Plant Water ◽  
Water Potentials ◽  
Cross Correlation Analysis ◽  
Plant Water Potential ◽  
Long Time

Water potential is a fundamental thermodynamic parameter that describes the activity of water. In this paper, we describe the continuous measurement of plant water potential, a reliable indicator of its water status, using a novel in situ sensor known as a microtensiometer in mature grapevines under field conditions. The microtensiometer operates on the principle of equilibration of water potentials of internal liquid water with an external vapour or liquid phase. We characterised the seasonal and diurnal dynamics of trunk water potentials (Ψtrunk) obtained from microtensiometers installed in two grapevine cultivars, Shiraz and Cabernet Sauvignon, and compared these values to pressure chamber-derived stem (Ψstem) and leaf (Ψleaf) water potentials as well as leaf stomatal conductance. Diurnal patterns of Ψtrunk matched those of Ψstem and Ψleaf under low vapour pressure deficit (VPD) conditions, but diverged under high VPD conditions. The highest diurnal values of Ψtrunk were observed shortly after dawn, while the lowest values were typically observed in the late afternoon. Differential responses of Ψtrunk to VPD were observed between cultivars, with Shiraz more sensitive than Cabernet to increasing VPD over long time scales, and both cultivars had a stronger VPD response than soil moisture response. On a diurnal basis, however, time cross correlation analysis revealed that Shiraz Ψtrunk lagged Cabernet Ψtrunk in response to changing VPD. Microtensiometers were shown to operate reliably under field conditions over several months. To be useful for irrigation scheduling of woody crops, new thresholds of Ψtrunk need to be developed.

Development of a sensor suite to determine plant water potential

2010 ◽  
Author(s):  
Vasu Udompetaikul ◽  
Shrini K Upadhyaya ◽  
David C Slaughter ◽  
Bruce D Lampinen
Keyword(s):  
Water Potential ◽  
Plant Water ◽  
Plant Water Potential ◽  
Sensor Suite

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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