scholarly journals Hydraulic Press Measurements of Leaf Water Potential in Groundnuts

1983 ◽  
Vol 19 (4) ◽  
pp. 287-291 ◽  
Author(s):  
G. Rajendrudu ◽  
M. Singh ◽  
J. H. Williams
Keyword(s):  
Regression Analysis ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Error Variance ◽  
Hydraulic Press ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Dew Point ◽  
Functional Relations ◽  
The Press

SUMMARYThe hydraulic press was compared with the dew point psychrometer and the pressure chamber methods for measuring leaf water potential (Ψ) in groundnuts (Arachis hypogaea L.). For measurements on the same leaf, regression analysis revealed that the slopes did not differ significantly from unity. An analysis of functional relations between measurements made by the press and the dew point psychrometer or the press and the pressure chamber showed that the error variance of the press was similar to those of the two other methods. Therefore, we conclude that for groundnuts the performance of the press, the dew point psychrometer and the pressure chamber are similar.

Comparisons between Press and Pressure Chamber Techniques for Measuring Leaf Water Potential

1981 ◽  
Vol 17 (1) ◽  
pp. 75-84 ◽  
Author(s):  
T. M. Yegappan ◽  
B. J. Mainstone
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Elaeis Guineensis ◽  
Water Status ◽  
High Water ◽  
Hydraulic Press ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Wide Range ◽  
The Press

SUMMARYA hydraulic press (the J-14) was compared with a Scholander pressure chamber to measure leaf water potential in Theobroma cacao, Gliricidia maculata, Cajanus cajan and Elaeis guineensis. Although the press satisfactorily estimated water status in soft, unhardened leaves of T. cacao, G. maculata and C. cajan at high water potential, it underestimated water status in hardened leaves of T. cacao. Satisfactory estimates were obtained at low water potential for hardened leaves of T. cacao but not for the others. There was a poor relation between readings of the two instruments for E. guineensis over a wide range of water potentials because press readings appeared to be influenced by leaf structure.

Evaluation of the hydraulic press for measurement of leaf water potentials in cassava

1983 ◽  
Vol 101 (2) ◽  
pp. 407-410 ◽  
Author(s):  
J. A. Palta
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Hydraulic Press ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Moisture Loss ◽  
Total Leaf Area ◽  
Water Potentials ◽  
Wide Range ◽  
Poor Relationship

SUMMARYIn the application of the Scholander pressure chamber technique to cassava water relations studies, the leaf water potential measured on central lobules was initially compared with that measured on entire leaves (including petiole). Measurements made using both a Campbell-Brewster hydraulic press and a pressure chamber of the leaf water potential in six different cassava clones were also compared. Although the central lobules showed a greater sensitivity to moisture loss after sampling than entire leaves, their leaf water potential was in close agreement with those measured on the entire leaves (r3 = 0·96). Therefore, for routine and field estimates in cassava, measurements made on the central lobules may be used to avoid the large reduction in total leaf area. The Campbell-Brewster hydraulic press satisfactorily estimated leaf water potential in M.Col. 1684 clone, which had the longest and narrowest lobules, but in other clones the leaf water potential was overestimated at high leaf potential (> -12·5) and underestimated at low water potentials (< -12·5). Over a wide range of leaf water potentials, a poor relationship between leaf water potentials estimated with hydraulic press and with the pressure chamber was observed for cassava because press estimates are influenced by lobule length and lobule width.

Evaluation of the pressure chamber technique for measurement of leaf water potential in cassava (Manihot species)

1978 ◽  
Vol 56 (14) ◽  
pp. 1638-1641 ◽  
Author(s):  
I. F. Ike ◽  
G. W. Thurtell ◽  
K. R. Stevenson
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Dew Point ◽  
Manihot Esculenta Crantz ◽  
Osmotic Potentials ◽  
Chamber Technique ◽  
Cassava Varieties

The pressure chamber technique was evaluated as a method for estimating leaf water potential in cassava (Manihot esculenta Crantz). Xylem pressure potentials (ψP) measured with the pressure chamber were compared with leaf water potential (ψL) obtained for the same leaf with the in situ dew-point hygrometer.In both cassava varieties studied, ψL and ψP were linearly related (r2 = 0.87 and 0.98 for CMC9 and CMC40 respectively). The length of petiole exposed outside the chamber affects the relation between ψL and ψP and should be kept at between 1 and 3 cm for better agreement. In CMC40, ψP was consistently lower (drier) than ψL by about 1.0 bar (1 bar = 100 kPa) in the entire range of water potential studied, but was not the case in CMC9. The reason for this difference is unclear but may be due to a filling of tissues other than xylem tissues (Boyer 1967) during the measurement of ψP in CMC40. Average xylem osmotic potentials (ψS) were low (−1.0 ± 0.2 bars and −1.0 ± 0.4 bars for CMC9 and CMC40 respectively). It is, therefore, unnecessary to correct for ψS when using the pressure chamber to estimate leaf water potentials in cassava.

Use of a Hydraulic Press for Estimation of Leaf Water Potential in Grain Sorghum 1

1986 ◽  
Vol 78 (4) ◽  
pp. 749-751 ◽  
Author(s):  
S. K. Hicks ◽  
R. J. Lascano ◽  
C. W. Wendt ◽  
A. B. Onken
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Grain Sorghum ◽  
Hydraulic Press ◽  
Leaf Water

The relationship between steady-state transpiration rates and leaf water potential in cassava (Manihot esculenta cv. Llanera)

1978 ◽  
Vol 56 (13) ◽  
pp. 1537-1539 ◽  
Author(s):  
I. F. Ike ◽  
G. W. Thurtell ◽  
K. R. Stevenson
Keyword(s):  
Steady State ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Manihot Esculenta ◽  
Regression Line ◽  
Leaf Water ◽  
Dew Point ◽  
Manihot Esculenta Crantz ◽  
The Relationship

The relationship between leaf water potential (ψL) and transpiration rate (T) was investigated using indoor-grown cassava plants (Manihot esculenta Crantz cv. Llanera). Leaf water potentials were measured with in situ dew-point hygrometer and transpiration rates by gas exchange analysis technique.Regression analyses of the data showed that T was consistently linearly related to ψL (r2 = 0.94). This implies that the plant resistance to flow was constant and hence that an Ohm's Law analog is valid for the transpiration range studied. Extrapolated values of leaf water potential at zero transpiration were close to the osmotic potential of the nutrient solution. Calculated resistance values (slope of regression line for individual plants) varied between 2.90 and 3.05 bars dm2 h g−1 (1 bar = 100 kPa).

scholarly journals Vine water deficit : among the 3 applications of pressure chamber, stem water potential is the most sensitive indicator

OENO One ◽  
2000 ◽  
Vol 34 (4) ◽  
pp. 169
Author(s):  
Xavier Choné ◽  
Olivier Trégoat ◽  
Cornelis Van Leeuwen ◽  
Denis Dubourdieu
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Water Status ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Sensitive Indicator ◽  
Stem Water Potential ◽  
Water Deficits ◽  
Stem Water

<p style="text-align: justify;">Vine water status is an important factor in grape quality. High tannin and anthocyanin content in red grape berries are related to moderate vine water deficits. Hence, a simple and sensitive indicator is required to determine vine water status and especially water constraint. Pressure chamber allows a quick and easy to practice determination of water status in the vineyard. Three applications of pressure chamber are known: predawn leaf water potential (ΨB), leaf water potential (ΨF) and stem water potential (ΨT). Only ΨB and ΨF are widely used on vines. In this survey ΨB, ΨF, ΨT and transpiration flow were measured on mature leaves to determine non-irrigated vine water status in field grown vines during the growing season. In California as well as in France, stem Ψ was the most discriminating indicator for both moderate and severe water deficits. In every plot surveyed ΨT was much better correlated to leaf transpiration than ΨF. Moreover, ΨT revealed nascent water deficit earlier than ΨB did. Among the three application of pressure chamber, ΨT was the only one to indicate short term water deficit after a rainfall. Hence, ΨT appears to be a useful indicator for grapevine management in both non-irrigated and irrigated vineyards.</p>

Errors Arising From Rapid Water Loss in the Measurement of Leaf Water Potential by the Pressure Chamber Technique

1980 ◽  
Vol 7 (5) ◽  
pp. 527 ◽  
Author(s):  
NC Turner ◽  
MJ Long
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Water Loss ◽  
Water Retention ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Diurnal Changes ◽  
Water Potentials ◽  
Retention Characteristics ◽  
Flow Through

In rapidly transpiring leaves, the water potentials of uncovered leaves measured in a pressure chamber were 0.2-0.7 MPa lower than the water potentials of leaves that were covered with a plastic sheath from just prior to their excision to the completion of the measurement. The error in the water potential of uncovered leaves arose from rapid water loss in the first 30 s after excision. The degree to which the water potentials were lowered depended on the rate of transpiration, the leaf water potential at the time of excision, the species, and whether the plants were grown in the glasshouse or field. It is suggested that the variation between species and between glasshouse-grown and field-grown plants arises from differences in water retention characteristics of plant tissue as well as to differences in the rates of transpiration at excision. The size of the error induced by the rapid water loss on diurnal changes in leaf water potential is demonstrated and the effect of the error in the calculation of turgor potentials and in the resistances to water flow through the plant is discussed.

Bias in pressure chamber measurements of leaf water potential

1982 ◽  
Vol 27 (3-4) ◽  
pp. 257-263 ◽  
Author(s):  
J.E. Leach ◽  
T. Woodhead ◽  
W. Day
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Chamber Measurements
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