Accuracy and Usefulness of Psychrometer and Pressure Chamber for Evaluating Water Potentials of Pinus radiata Needles

1982 ◽  
Vol 9 (5) ◽  
pp. 499 ◽  
Author(s):  
BD Millar
Keyword(s):  
Water Potential ◽  
Pinus Radiata ◽  
Xylem Sap ◽  
Pressure Chamber ◽  
Pressure Potential ◽  
Pine Trees ◽  
Average Water ◽  
Potential Gradients ◽  
Fundamental Uncertainty ◽  
The One

Pressure chamber evaluations of xylem sap pressure potential (P) and thermocouple psychrometric evaluations of average water potential (Ψl) in needles from both transpiring and non-transpiring pine trees (Pinus radiata D. Don) were compared in order to determine the relative accuracy and usefulness of these methods for assessing Ψl. Markedly different but linear P v. Ψl relationships were obtained for pine needles of different age and also for the case where resin exudation masked the xylem and led to a 'resin error'. Evidence suggests that these differences are mainly due to injection and resin errors in pressure chamber determinations totalling as much as 1 MPa (a 10 bar). The psychrometric method appears to be the much more accurate. Radial water potential gradients across leaves did not result in differences between evaluations of P and Ψl, at least in P. radiata. The need for multiple 'calibrations' of the pressure chamber and the fundamental uncertainty about the constancy of such calibrations on the one hand and the slowness of the excised-needle psychrometer on the other can restrict the usefulness of these methods.

The hydraulic architecture of Thuja occidentalis

1983 ◽  
Vol 61 (8) ◽  
pp. 2105-2111 ◽  
Author(s):  
M. T. Tyree ◽  
M. E. D. Graham ◽  
K. E. Cooper ◽  
L. J. Bazos
Keyword(s):  
Water Potential ◽  
Water Flow Rate ◽  
Potential Gradient ◽  
Pressure Potential ◽  
Thuja Occidentalis ◽  
Unit Leaf ◽  
Leaf Surface Area ◽  
Potential Gradients ◽  
Evaporative Flux ◽  
Stem Segments

Leaf specific conductivities (LSC's) were measured on stem segments excised from various points within the canopy of eastern white cedar trees, Thuja occidentalis L. LSC is defined as the water flow rate (kilograms per second) through a stem caused by a unit of pressure potential gradient (megapascals per metre) per unit leaf surface area supplied by the stem (square metres). LSC's were measured on stems of various diameters and were found to vary over a factor of 30 in magnitude from 1 × 10−5 kg s−1 m−1 MPa−1 for stems 1 mm in diameter to 3 × 10−4 kg s−1 m−1 MPa−1 for stems 100 mm in diameter. LSC was found to be related to stem diameter (D (millimetres)) by the following empirical formula: LSC = 9.58 × 10−6 × D0.727. LSC's measured on stem segments including a node had significantly lower LSC's than internodal stem segments of the same length. Various water relations parameters were measured on cedar trees on a diurnal basis including evaporative flux, leaf resistance to evaporation, shoot water potential, air temperature, and air humidity. Water potential isotherms were also measured on excised green shoots. From the above data, we estimate that about 15% of the total water evaporated from green shoots comes from stored water while the shoot water potentials are growing progressively negative. The typical peak evaporative flux in midday was 1.5 × 10−5 kg s−1 m−2; using this value and our measured LSC's we estimate that the pressure potential gradients in the stems must be 50 kPa m−1 in stems 100 mm in diameter and 1500 kPa m−1 in stems 1 mm in diameter. Pressure potential gradients were measured in stems 30 to 50 mm in diameter by the pressure bomb technique and were found to be 69 kPa m−1 during a typical afternoon and this confirms the accuracy of the above estimates.

scholarly journals Comparisons of Leaf Water Potential and Xylem Water Potential in tomato Plants

1970 ◽  
Vol 23 (2) ◽  
pp. 485 ◽  
Author(s):  
HD Barrs ◽  
B Freeman ◽  
J Blackwell ◽  
RD Ceccato
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Present Communication ◽  
Pressure Potential ◽  
Xylem Water Potential ◽  
Tomato Plants ◽  
Water Potentials ◽  
Xylem Pressure Potential

The rapidity and convenience of the pressure chamber technique for estimating leaf water potentials, especially under field conditions, has been remarked (Boyer 1967; Kaufmann 1968a, 1968b) and demonstrated (Klepper and Ceccato 1969). However, Kaufmann (1968a) showed that it is necessary to exercise caution .in using measurements made with the pressure chamber as direct estimates of leaf water potential. Instead, he recommended that calibration curves should be drawn up for each species, relating measurements of xylem pressure potential obtained with this technique to corresponding known leaf water potentials. The present communication reports such a relation for tomato leaves, which have not previously been studied in this way. Plant age is shown to affect the relation.

scholarly journals Drought Adaptation in Fuchsia magellanica and Its Effect on Freezing Tolerance

2008 ◽  
Vol 133 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Majken Pagter ◽  
Karen K. Petersen ◽  
Fulai Liu ◽  
Christian R. Jensen
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Freezing Tolerance ◽  
Woody Plants ◽  
Xylem Sap ◽  
Water Deficiency ◽  
Frost Injury ◽  
Different Types ◽  
Curvilinear Relation ◽  
Reduced Water

Fuchsia (Fuchsia L.) is a popular woody ornamental, but it is very susceptible to frost injury during winter. As drought stress may be used to enhance freezing tolerance in woody plants, the effects of different types of water deficit on growth, selected physiological traits, and freezing tolerance were examined in Fuchsia magellanica Lam. ‘Riccartonii’. Drought responses were investigated after 6 weeks of pretreatment, where individual plants grown in a greenhouse under conditions of unrestricted water supply were compared with plants subjected to cyclic or continuous water deficit. After an additional 4 weeks of treatment at short day (10 h) and low temperature (8 °C day/4 °C night), freezing tolerance was examined. Both continuous and cyclic water deficit plants reduced water loss by reducing aboveground biomass and by efficient stomatal regulation. Continuous water deficit plants tended to adjust osmotically, while cyclic water deficit induced significantly higher xylem sap abscisic acid [(ABA)xylem] and leaf proline concentrations and a lower leaf water potential (ψl) than continuous water deficit, indicating that F. magellanica responds differently to continuous water deficit and to fast drying associated with stress phases of cyclic water deficit. The root water potential (ψr) and (ABA)xylem were negatively linearly correlated, implying that increasing water deficiency stimulated formation of ABA in the roots. An inverse, curvilinear relation between (ABA)xylem and stomatal conductance (g s) indicated that root-originated ABA might control g s during mild water deficits. Neither cold-acclimating conditions alone nor combined with water deficit increased stem freezing tolerance, indicating that F. magellanica lacks cold-acclimation ability under the inductive conditions used in this study.

Linguistic organization of the duality of mythological worlds in B. Pasternak’s poem "Wind" ("Veter")

2021 ◽  
Vol 82 (5) ◽  
pp. 74-79
Author(s):  
I. V. Yakushevich
Keyword(s):  
Actual World ◽  
Symbolic Meaning ◽  
Lexical Resources ◽  
Fictional World ◽  
The Past ◽  
Poetic Text ◽  
Pine Trees ◽  
The One ◽  
Main Ideas ◽  
Linguistic Means

This article presents a linguopoetic analysis of Boris Pasternak’s poem "Wind" ("Veter") from the position of the lingual embodiment of the duality of mythological worlds. This research focuses on the symbol of "the wind as a spirit", upon which the poem’s whole mystical idea relies. The purpose of this article is to reveal which the linguistic means used to translate the duality of mythological worlds, as well as how this cognition merges with the author’s experience and determines the poem’s figurative system and idea. The understanding of the duality of mythological worlds requires the law of participation (L. L vy-Bruhl) – the identification of the mental, emotional, and physical properties of a person and nature. In Pasternak’s poem, the suffering and rushing "I" of the deceased lyrical hero becomes the wind. In this study, the word-symbol "wind" is studied in the semantic and semiotic aspect as a sign. Its signifier is the lexeme wind meaning 'perceptual idea of an air flow'; signified – the symbolic meaning of 'spirit, soul, immortality', due to the etymological meaning of the word and pagan mythology. The results reveal that the symbol "wind" is the carrier of the duality of mythological worlds, and it programs the fictional world of the poem: on the one hand, these are the actual world of the lyrical heroine, the house, and the wind, which swings pine trees; on the other hand – the imaginary world of the spirit of the dead lyrical hero. The lexical resources of the poetic text translate this opposition in the ratio of the words I and wind, personal pronouns I and you, as well as the words ended and alive. At the grammatical level, the duality is expressed by the contrast of the verbal forms of the past and present time, as well as by the passage from the indirect thought (the lyrical hero’s mental monologue) to the 3rd person narrative about the wind and the pine trees and by the return of the poem to the lyrical hero’s indirect thought at the end. This is how Pasternak implements one of the main ideas of his novel "Doctor Zhivago" – the idea of immortality, which is confirmed in the article by referring to the novel’s macro context and biographical materials.

scholarly journals Growth Dynamics and Water Potential Components of Three Summer Squash (Cucurbita pepo L.) Cultivars

2015 ◽  
Vol 43 (2) ◽  
pp. 420-425 ◽  
Author(s):  
Alejo RODRÍGUEZ-BURGOS ◽  
Armando CARRILLO-LÓPEZ ◽  
Tomás OSUNA-ENCISO ◽  
Manuel BÁEZ-SAÑUDO ◽  
Adriana SAÑUDO-BARAJAS ◽  
...  
Keyword(s):  
Water Potential ◽  
Histological Analysis ◽  
Growth Dynamics ◽  
Titratable Acidity ◽  
Soluble Solids ◽  
Pressure Potential ◽  
Horticultural Crop ◽  
Total Soluble Solids ◽  
Summer Squash ◽  
Postharvest Life

Summer squash fruit is a horticultural crop that possesses a very short postharvest life due to its high rates of metabolism and transpirationalong with a low cuticle resistance exhibited mainly when the fruit is harvested at horticultural maturity. This research was realized following thefruit growth of the summer squash cultivars: ‘Enterprise’, ‘Pascola’ and ‘Hurakan F1’, whose seeds were germinated in polystyrene trays and theirseedlings were subsequently transferred to pots for optimum growth under greenhouse conditions. Fruits were sampled at 3, 5, 7 and 9 days afteranthesis (DAA). Physical (weight, diameter, and length of fruit), chemical (pH, titratable acidity and total soluble solids), hydric status (water,osmotic and pressure potentials), and histological analysis were done. The highest number of fruits having marketing quality were shown in both‘Pascola’ and ‘Hurakan F1’ cultivars at 7 DAA, whereas, in ‘Enterprise’ was shown at 9 DAA. Marketing quality fruits from the three cultivarsshowed similarities on pH (about 6.6), titratable acidity (TA) decreases in ‘Enterprise’ and ‘Hurakan F1’, whereas total soluble solids (TSS)decreases in ‘Pascola’ and ‘Hurakan F1’ (pJ 0.5). From 3 to 9 DAA, in all cultivars, the water potential was close to -1.0 MPa, the osmoticpotential showed an increasing pattern ranging between -1.59 and -1.15 MPa, and the pressure potential remained in the positive range. Tissuewater stability was histologically related to a well-defined parenchyma tissue showing thin-walled, polygonal, intact and turgid cells during fruitgrowth.

Comparative analysis reveals gravity is involved in the MIZ1-regulated root hydrotropism

2020 ◽  
Vol 71 (22) ◽  
pp. 7316-7330
Author(s):  
Ying Li ◽  
Wei Yuan ◽  
Luocheng Li ◽  
Hui Dai ◽  
Xiaolin Dang ◽  
...  
Keyword(s):  
Water Potential ◽  
Double Mutant ◽  
Root Elongation ◽  
Vertical Orientation ◽  
Tomato Plants ◽  
Oblique Orientation ◽  
Experimental Systems ◽  
Potential Gradients ◽  
Insight Into

Abstract Hydrotropism is the directed growth of roots toward the water found in the soil. However, mechanisms governing interactions between hydrotropism and gravitropism remain largely unclear. In this study, we found that an air system and an agar–sorbitol system induced only oblique water-potential gradients; an agar–glycerol system induced only vertical water-potential gradients; and a sand system established both oblique and vertical water-potential gradients. We employed obliquely oriented and vertically oriented experimental systems to study hydrotropism in Arabidopsis and tomato plants. Comparative analyses using different hydrotropic systems showed that gravity hindered the ability of roots to search for obliquely oriented water, whilst facilitating roots’ search for vertically oriented water. We found that the gravitropism-deficient mutant aux1 showed enhanced hydrotropism in the oblique orientation but impaired root elongation towards water in the vertical orientation. The miz1 mutant exhibited deficient hydrotropism in the oblique orientation but normal root elongation towards water in the vertical orientation. Importantly, in contrast to miz1, the miz1/aux1 double mutant exhibited hydrotropic bending in the oblique orientation and attenuated root elongation towards water in the vertical orientation. Our results suggest that gravitropism is required for MIZ1-regulated root hydrotropism in both the oblique orientation and the vertical orientation, providing further insight into the role of gravity in root hydrotropism.

Physiological trade-offs associated with methyl jasmonate - induced resistance in Pinus radiata

2008 ◽  
Vol 38 (4) ◽  
pp. 677-684 ◽  
Author(s):  
Nick Gould ◽  
Tony Reglinski ◽  
Mike Spiers ◽  
Joe T. Taylor
Keyword(s):  
Growth Rate ◽  
Disease Resistance ◽  
Methyl Jasmonate ◽  
Water Potential ◽  
Seedling Growth ◽  
Pinus Radiata ◽  
Transpiration Rate ◽  
Meja Treatment ◽  
Seedling Growth Rate ◽  
The Impact

Methyl jasmonate (MeJA) can induce defence responses in plants to pathogen attack, but it can also have consequences for plant growth. The transient effects of exogenous MeJA treatment on the resistance of Monterey pine ( Pinus radiata D. Don) seedlings to Diplodia pinea (Desm.) Kickx. and some physiological parameters affecting the impact of treatment on seedling growth were investigated. Following foliar application of 4.5 mmol·L–1 MeJA, disease resistance was greatest 1–2 weeks after treatment and declined with time thereafter. Elevated disease resistance was accompanied by a reduction in seedling growth rate the second week following MeJA treatment. Thereafter, seedling growth rate recovered and exceeded that of the control seedlings 4–5 weeks after MeJA treatment. Within hours of MeJA treatment, reductions in both the capacity of photosystem II and transpiration rate were observed, resulting in a concomitant reduction in net CO2 uptake rate. The slight reduction in transpiration rate was also associated with an increase in needle water potential. Longer term measurements showed no effect of MeJA on photosynthetic rate, transpiration rate, chlorophyll content, or shoot water potential and thus could not account for the elevated growth rate observed 4–5 weeks after treatment.

Loss of pod set caused by drought stress is associated with water status and ABA content of reproductive structures in soybean

2003 ◽  
Vol 30 (3) ◽  
pp. 271 ◽  
Author(s):  
Fulai Liu ◽  
Mathias N. Andersen ◽  
Christian R. Jensen
Keyword(s):  
Drought Stress ◽  
Water Potential ◽  
Seed Yield ◽  
Water Status ◽  
Xylem Sap ◽  
Physiological Maturity ◽  
Reproductive Structures ◽  
Glycine Max L ◽  
Aba Content ◽  
Days After Anthesis

Drought stress occurring during flowering and early pod expansion decreases pod set in soybean (Glycine max L. Merr.). The failure of pod set may be associated with changes in water status and ABA content in soybean reproductive structures under drought stress. To test this, pot experiments in an environmentally-controlled greenhouse were conducted, in which soybeans were exposed to drought stress around anthesis. In a preliminary experiment (Expt. I), irrigation was withheld at –6 (D1), –4 (D2) and –2 (D3) to 11 days after anthesis (DAA), then the droughted plants were re-watered to control levels until physiological maturity. Pod set percentage, seed yield and yield components were recorded. In the main experiment (Expt. II), irrigation was withheld from –11 to 10�DAA. During the drying cycle, parts of the droughted plants were re-watered at 0, 3, 5, 7 and 10 DAA and kept well-watered until physiological maturity. In Expt. II, water status, ABA contents in xylem sap, leaves, flowers and pods were measured at 0, 3, 5, 7 and 10 DAA. The water potential in the flowers and pods was always lower than the leaf water potential. Turgor was decreased in leaves by drought 3 DAA, but remained at control levels in flowers and pods. Compared with well-watered plants, in severely droughted plants (10 DAA), xylem [ABA] increased about 60-fold; leaf [ABA] increased 9-fold; pod [ABA] increased 6-fold. During soil drying, flower and pod [ABA] was linearly correlated with xylem [ABA] and leaf [ABA], indicating that root-originated ABA and/or leaf ABA were the likely sources of ABA accumulated in the flowers and pods. In Expt. I, pod set and seed number per pod was unaffected by drought stress, while seed yield and individual seed weight was significantly decreased by drought. In Expt. II, significant reductions in pod set and seed yield were observed when re-watering the droughted plants at 3–5 DAA, re-watering the droughted plants later than this stage resulted in a similar pod set. Collectively, these results suggest that drought-induced decrease in water potential and increase in ABA content in flowers and pods at critical developmental stage (3–5 DAA) contribute to pod abortion in soybean.

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