Spatial and temporal variability of soil water in drylands: plant water potential as a diagnostic tool

2008 ◽  
Vol 10 (2) ◽  
pp. 74-80 ◽  
Author(s):  
Maik Veste ◽  
Markus Staudinger ◽  
Manfred Küppers
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Diagnostic Tool ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
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

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.

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.

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.

Seasonal changes in the water balance of Douglas-fir (Pseudotsuga menziesii) seedlings grown under different light intensities

1979 ◽  
Vol 57 (6) ◽  
pp. 666-674 ◽  
Author(s):  
Allan P. Drew ◽  
William K. Ferrell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Leaf Conductance ◽  
Soil Drought ◽  
Plant Water ◽  
Wide Range ◽  
Plant Water Potential ◽  
Lower Plant

The water relations of germinant seedlings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) grown outdoors under 9, 44, and 100% full light were analyzed during the summer, autumn, and winter seasons. Empirical regression models, based on the relationship plant water potential = f(soil water potential, leaf conductance), were determined for selected light treatment – season combinations. Plant water potential is higher during active summer shoot growth than after elongation growth has ceased in the autumn owing to earlier stomatal closure in response to soil drought in summer compared with a more abrupt closure at a lower plant water potential in the autumn.For all light treatments, leaf conductance declined in the winter independent of plant water potential and simultaneously with the onset of subfreezing air temperatures. During the first winter, water potential of seedlings was higher than during the previous summer or autumn over a wide range of equivalent soil water potentials.Seedlings grown under low light intensity are less drought resistant and have lower plant water potential than those grown under full light regardless of soil moisture status.

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