Measurement of Energy Status of Water in Plants With a Thermocouple Psychrometer

Ehlig, C. F.

doi:10.1104/pp.37.3.288

Cited by 91 publications

(37 citation statements)

References 4 publications

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“…Despite the initial trend for the use of own manufactured equipment (Spanner, 1951;Ehlig, 1962;Campbell and Campbell, 1974; …”

Section: Commercial Equipmentsmentioning

confidence: 99%

“…The first study that addressed measurements of leaf water potential was carried out by Ehlig (1962), who measured osmotic potential and diffusion pressure deficit in individual leaves by using a slightly modified Richards-type TCP in greenhouses. Ehlig (1962) presented TCP as a method that allowed for the determination of osmotic potential and diffusion pressure deficit with a measurement range 0.33-1.13 MPa requiring a single leaf and short preparation time.…”

Section: Measurement Of Leaf Water Potentialmentioning

confidence: 99%

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Review. Use of psychrometers in field measurements of plant material: accuracy and handling difficulties

Martínez¹,

Cancela²,

García³

et al. 1970

Span. j. agric. res.

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For years, one of the major concerns of agronomists has been the study of how variations in the crop environment can affect proper crop development. A variety of factors must be considered, including factors such as plant genetics, climatic conditions or soil, and factors directly dependent on man such as technology or labour. In the search for sustainable development, all these factors must coexist in perfect harmony in order AbstractThe determination of leaf water potential is useful in the establishment of irrigation guidelines for agricultural crop management practices and requires the use of various methods, among which thermocouple psychrometers (TCP). TCP have been widely used for this purpose. However, the psychrometric technique is complex and difficult to understand and the instrumentation required is difficult to handle. For this reason, a profound knowledge of the different aspects involved in the technique -which have not been clearly explained in the literature-is required. This paper reviews a number of research areas of TCP and focuses on three very specific fields: a) main applications of phsychrometry in field studies; b) determination of the measurement accuracy of psychrometric equipment, accuracy per se and accuracy tested against alternative methods; c) main errors and handling difficulties of TCP in the field. Research in these areas provides an updated overview of TCP as a method for determining water relations in plant material that will contribute criteria to select the most suitable technique according to the type of plant material and the purpose of the research and will highlight the types of instruments, accuracies and errors that have detrimental effects on measurements.Additional key words: hygrometric technique; irrigation; isopiestic technique; pressure chamber; psychrometric technique. ResumenRevisión. Aplicación de la psicrometría en campo a material vegetal: precisión y dificultades de manejo La determinación del potencial hídrico foliar es muy útil en el establecimiento de directrices de riego en las prácti-cas de manejo agrícola de los cultivos, requiriéndose del uso de diferentes métodos como los psicrómetros termopar (TCP). Los TCP han sido ampliamente utilizados. Sin embargo, se trata de una técnica compleja de difícil manejo. Por lo tanto, se requiere un profundo conocimiento de los diferentes aspectos involucrados en la técnica, que no han sido claramente explicados en los diferentes estudios publicados. Este artículo revisa una serie de líneas de investigación de los TCP. Estas áreas de investigación se han centrado en tres campos muy específicos: a) principales actuaciones en campo empleando la psicrometría; b) especificación de la precisión de los equipos, per se y frente a otras metodologías alternativas; c) principales errores y dificultades de manejo en campo de los psicrómetros. La investigación en esta área permitirá aportar una visión actualizada sobre los TCP como método de determinación de relaciones hídricas en material vegetal, aportando criterios de sele...

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“…Despite the initial trend for the use of own manufactured equipment (Spanner, 1951;Ehlig, 1962;Campbell and Campbell, 1974; …”

Section: Commercial Equipmentsmentioning

confidence: 99%

Section: Measurement Of Leaf Water Potentialmentioning

confidence: 99%

Review. Use of psychrometers in field measurements of plant material: accuracy and handling difficulties

Martínez¹,

Cancela²,

García³

et al. 1970

Span. j. agric. res.

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“…In both soil and plant systems. these 5 The lid was molded with a 6 cm diameter hole in the center into which a bored-out cork was placed. The roots of a seedling were put through the hole of the cork and split equally between 2 culture solutions.…”

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confidence: 99%

Leaf Water Potential of Differentially Salinized Plants

1969

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Abstract. Water and osmotic potential energies were measured with thermocouple psvchrometers, at intervals during a 4-week period, in growing leaves of bean (Phaseolus vulgaris, var. Blue Lake) and barley (Hordeum vulgare, var. Liberty) plants having roots equally split between 2 differentially salinized nutrient solutions. The osmotic potentials of plants with half their roots in saline solutions were about halfway between the osmotic potentials of plants grown in nonsaline solutions and those grown in saline solutions. By the end of the 4-week measurement period, the beans and barley were almost mature. The final dry weights of shoots of plants with half their roots in saline solutions were about halfway between the dry weights of the shoots of plants grown in nonsaline solutions and the dry weights of those in saline solutions. The results obtained showed that the degree of osmotic adjustment and the rate of growth were functions of the proportion of the root system exposed to saline conditions.There are relatively few reported experinments oni water uptake by l)lant root systemiis growing under a nonuniform-i distribution of salt concentration (4, 9, 10). It is known that when saline conditions vary with depth, water extraction is niot uniform with depth (11). Often a plant does not extract the more saline water toward the bottom of its root zone until most of the less saline water has 'been removed from the tupperl root zone (7). During the water extraction process. differences in total potential, osmotic potential, pressure potential, matric potential, and gravitational potential can develop in the water of the root zonie (soil water) or in the water of a part of the plant, for exanmple, a leaf. In both soil and plant systems. these 5

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“…However, visual examination of such tissue shows minute droplets on its surface. Since Ehlig (5) reported that the accumulation of salt on the surface of cotton leaves caused spurious depressions in his psychrometric determinations of water potential, salt secretion could be responsible for the failure to attain a stable equilibrium in our experiments with this species.…”

Section: Methodsmentioning

confidence: 95%

Effects of Salt Secretion on Psychrometric Determinations of Water Potential of Cotton Leaves

Klepper¹,

Barrs²

1968

Plant Physiol.

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A bstract. Thermocouple psychrometers gave lower estimates of water potential of cotton leaves 'than did a pressure chan-ber. This difference was considerable for turgid leaves, but progressively decreased for leaves with lower water potentials and fell to zero at water potentials below about -10 bars. The oonductivity of washings from cotton leaves removed from the psychrometric equilibration chambers was related to the magnitude of -this disorepancy in water potential, indicating that the discrepancy is due to salts on the leaf surface which make the psychrometric estimates too low. This error, which may be as great as 400 to 500 %, oannot be eliminated by washing the leaves because salts may be secreted during the equilibration period. Therefore, a thermocouple psyohrometer is not suitable for measuring the water potential of cotton leaves when it is above about -10 bars.

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Measurement of Energy Status of Water in Plants With a Thermocouple Psychrometer

Abstract: The thermocouple psvchromiieter (leveloped by Richardls and Ogata (1)

Cited by 91 publications

References 4 publications

Review. Use of psychrometers in field measurements of plant material: accuracy and handling difficulties

Review. Use of psychrometers in field measurements of plant material: accuracy and handling difficulties

Leaf Water Potential of Differentially Salinized Plants

Effects of Salt Secretion on Psychrometric Determinations of Water Potential of Cotton Leaves

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