Effect of Stem Excision Under Water on Bulk Leaf Water Potential, Leaf Conductance, CO2 Assimilation and Stemwood Water Storage in Eucalyptus behriana F. Muell

1987 ◽  
Vol 14 (2) ◽  
pp. 135 ◽  
Author(s):  
BA Myers ◽  
M Kuppers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Intercellular Co2 Concentration ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Bulk Water ◽  
Leaf Conductance ◽  
Leaf Water ◽  
Stem Cutting

Cutting the stem, under water and above the lignotuber, of intact trees of Eucalyptus behriana caused rapid increases in the bulk leaf water potential (Ψ) in the canopy above. In eight separate experiments the mean increase in Ψ of 3.1 MPa in 1 h was associated with rapid and persistent decreases in leaf conductance (g), which have been ascribed to hydropassive changes in leaf turgor. The water content of the stemwood increased by 1.8-2.0% as the bulk water potential increased by approximately 2.5 MPa. In the first hour after cutting the stems under water, the observed rate of water uptake by the cut stem was approximately six times the estimated transpiration rate of the leaves. This discrepancy is attributed to an increase in stem water content. The specific capacitance of the stemwood was estimated to be 0.008 g g-1 (dry weight) Mpa-1. The quantity of water available from storage in the stem was estimated to be less than 0.1 mm. Continuous measurements of gas exchange on a leaf before, during and after stem-cutting showed that CO2 assimilation decreased in parallel with g, but in a manner that caused increases in intercellular CO2 concentration. This indicated that the rapid increases of bulk leaf turgor, induced by stem-cutting, affected photosynthetic capacity.

scholarly journals Capillary Mats Modify Media Moisture Content during Mist Propagation of Chrysanthemum Cuttings

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 634a-634
Author(s):  
Jennifer Marohnic ◽  
Robert Geneve ◽  
Jack W. Buxton
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Relative Water Content ◽  
Dry Weight ◽  
Leaf Water ◽  
Root Numbers ◽  
Relative Water ◽  
Leaf Relative Water Content ◽  
Initial Root

Capillary mats were used to vary the water content in oasis blocks during mist propagation of chrysanthemum cuttings. Mats placed on the surface of the propagation bench extended over the edge of the bench and downward a distance of either 0 or 20 cm. Oasis blocks with chrysanthemum cuttings `Boaloi' and `Salmon Charm' were placed on mats under intermittent mist (10 seconds every 5 minutes) between 5 am and 8 pm. Relative water content, mL of water/gram oasis, and leaf water potential were measured at noon every 5 days. After 26 days number of roots per cutting was evaluated. Water content in the oasis block was reduced by 49% (450 to 219 mL/g dry weight of oasis) by hanging the capillary mat 20 cm over the edge of the bench compared to 0 cm treatment. Cuttings showed an increase in leaf relative water content from 49% and 51% at day 1 to 65% and 71% by day 11 for `Boaloi' and `Salmon Charm', respectively. Following initial root formation, leaf relative water content increased to 85%. Over the course of the experiment `Boaloi' and `Salmon Charm' showed an average reduction in leaf water potential of 0.14 and 0.08 MPA, respectively. `Boaloi' showed overall higher root numbers than `Salmon Charm'; however, no difference in rooting between mat treatments was observed.

Agronomic and Physiological Responses of Soybean and Sorghum Crops to Water Deficits. III. Components of Leaf Water Potential, Leaf Conductance, 14co2 Photosynthesis and Adaptation to Water Deficits.

1978 ◽  
Vol 5 (2) ◽  
pp. 179 ◽  
Author(s):  
NC Turner ◽  
JE Begg ◽  
HM Rawson ◽  
SD English ◽  
AB Hearn
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Relative Water Content ◽  
Leaf Conductance ◽  
Leaf Water ◽  
Starch Accumulation ◽  
Water Deficits ◽  
Relative Water

Concurrent measurements of leaf water potential, leaf osmotic potential, leaf relative water content, quantum flux density, leaf conductance, 14CO2 photosynthesis, soluble and insoluble sugars, starch and potassium concentrations were made diurnally on six occasions between flowering and maturity on upper leaves of irrigated and rainfed crops of soybean (cvv. Ruse and Bragg) and a rainfed crop of sorghum (cv. TX 610). With adequate soil water, sorghum had lower values of leaf conductance than did soybeans at high light and yet had higher rates of photosynthesis. Stage of plant development had no effect on either leaf conductance or photosynthesis of the youngest fully expanded leaves of both sorghum and soybean, but starch accumulation in the leaf over the day was less at grain-filling than at flowering in the soybean. Starch and sugar levels in the leaf had no apparent effect on photosynthesis. The daily minimum leaf water potential decreased in Ruse soybean from - 1.5 to -2.7 MPa as soil water was depleted. Late in the drying cycle, the daily minimum leaf water potential was higher in Bragg than in Ruse. In both cultivars, stomatal closure and decrease in 14CO2 photosynthesis commenced at leaf water potentials below - 1.5 MPa. Thus, the effect of water deficits on leaf conductance and photosynthesis occurred later in the drying cycle in Bragg than Ruse. As photosynthesis decreased with the depletion of soil water, starch accumulation in leaves of both cultivars of soybean decreased; changes in soluble and insoluble sugars and in potassium were small. The relationships among leaf water potential, osmotic potential, turgor potential, and leaf relative water content did not change with season or soil water depletion. Bragg and Ruse soybeans showed a similar response and both approached zero turgor at the same relative water content (82-83 %) and the same leaf water potential (- 1.5 to - 1.7 MPa). No evidence ofr osmotic adjustment was found in either soybean cultivar.

Leaf Gas Exchange and Water Relations of Lupins and Wheat. I. Shoot Responses to Soil Water Deficits

1989 ◽  
Vol 16 (5) ◽  
pp. 401 ◽  
Author(s):  
IE Henson ◽  
CR Jensen ◽  
NC Turner
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Turgor Pressure ◽  
Leaf Conductance ◽  
Leaf Water

The effects of a progressive increase in soil water deficit on the leaf conductance and gas exchange of lupin (Lupinus cosentinii) and wheat (Triticum aestivum) were investigated in pot experiments in a temperature-regulated glasshouse, using a coarse, sandy soil characteristic of the Western Australian wheatbelt. Transpiration rates decreased rapidly in both species after water was withheld, mainly as a result of stomatal closure. Photosynthesis declined also, but to a lesser extent than conductance. Leaf extension in lupin was equally as sensitive to a decrease in leaf water potential and soil water potential as stomatal conductance. Stomatal closure served to maintain the water potential of lupin leaves to within 0.1 MPa of that of control (watered) plants as the soil water content decreased from 0.14 to 0.06 m3 m-3 and as the leaf conductance and the relative transpiration rate fell to less than 50% of control values. Maintenance of leaf water potential with decreasing soil water content and stomatal conductance was less evident in wheat. In both lupin and wheat, leaf conductance decreased linearly with soil water content and curvilinearly with bulk soil matric potential, indicating that water uptake was restricted at similar water contents and matric potentials in both species. Diurnal measurements on lupin indicated a substantial reduction in stomatal conductance after water was withheld, even when the leaf water potential at midday was reduced by only 0.1 MPa and no change could be detected in the bulk leaf turgor pressure. Conductance in lupin was reduced even though the soil matric potential decreased in only part of the rooting zone. This, together with the absence of any significant change in the leaf water potential, turgor pressure, or relative water content in lupin during the initial stages of stomatal closure, suggests that a soil or root factor initiates the reduction in leaf conductance - and hence regulates the shoot water status - in response to soil drying.

Seasonal changes in leaf water potential components in two almond cultivars

1993 ◽  
Vol 120 (3) ◽  
pp. 347-351 ◽  
Author(s):  
M. C. Ruíz-Sánchez ◽  
M. J. Sánchez-Blanco ◽  
J. Planes ◽  
J. J. Alarcón ◽  
A. Torrecillas
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Leaf Osmotic Potential ◽  
Relative Water ◽  
Almond Trees ◽  
Amygdalus Communis

SUMMARYAlmond trees (Amygdalus communis L. cvs Garrigues and Ramillete) were grown in the field under non-irrigated conditions in Murcia, Spain. Seasonal variations in leaf water potential components were studied in 1989. Predawn leaf water potential showed high values in both cultivars, due to the absence of soil water stress. Pressure-volume curve analysis indicated that the leaf osmotic potential at full saturation (Ψo(sat)) for cv. Garrigues remained fairly constant throughout the season. Bulk modulus of elasticity (E) showed, in both cultivars, a tendency to decrease as the season progressed. E values were higher in Ramillete than in Garrigues. The relative water content at the turgor loss point (RWCtlp) seemed to be controlled by E values. The larger relative apoplastic water content (RWCa found in Ramillete might have allowed it to retain more water at low leaf water potentials than Garrigues. These facts would support the suggestion that Ramillete is a more drought-resistant cultivar than Garrigues.

Water Relations and Leaf Structure of the Evergreen Shrubs Eurya emarginata (Theaceae) and E. japonica in Coastal and Inland Habitats

1998 ◽  
Vol 46 (1) ◽  
pp. 135 ◽  
Author(s):  
Masako Mishio ◽  
Naoki Kachi
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Leaf Water Potential ◽  
Unit Area ◽  
Leaf Water ◽  
Photon Flux ◽  
Leaf Water Content ◽  
Shrub Species ◽  
Eurya Emarginata

Stomatal conductance and leaf water potential at around noon, pre-dawn leaf water potential, pressure–volume parameters, and leaf structural characteristics including leaf thickness, leaf dry mass per unit area and turgid leaf water content per unit area were compared between a coastal shrub species, Eurya emarginata (Thunb.) Makino and an inland shrub species, E. japonica Thunb. The pre-dawn leaf water potential was only slightly lower in E. emarginata than in E. japonica, and the environmental conditions such as the photosynthetic photon flux density and the vapour pressure deficit did not differ obviously between the two habitats. No apparent differences were observed in the pressure–volume parameters between the two species. On the other hand, E. emarginata had much higher stomatal conductance and significantly thicker leaves with higher turgid leaf water content per unit area than E. japonica. The thicker leaf with higher water content on an area basis in E. emarginata maintains adequate leaf turgor pressure against a higher rate of transpiration.

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