scholarly journals Relationship of Xylem Embolism to Xylem Pressure Potential, Stomatal Closure, and Shoot Morphology in the Palm Rhapis excelsa

1986 ◽  
Vol 80 (1) ◽  
pp. 110-116 ◽  
Author(s):  
John S. Sperry
Keyword(s):  
Stomatal Closure ◽  
Pressure Potential ◽  
Xylem Embolism ◽  
Shoot Morphology ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
Relationship Of

Xylem Embolism in the Palm Rhapis Excelsa

IAWA Journal ◽  
1985 ◽  
Vol 6 (4) ◽  
pp. 283-292 ◽  
Author(s):  
John S. Sperry
Keyword(s):  
Flow Resistance ◽  
Stomatal Closure ◽  
Gas Embolism ◽  
Hydraulic Architecture ◽  
Pressure Potential ◽  
Xylem Embolism ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
Prolonged Drought ◽  
Xylem Flow

Xylem failure via gas embolism (cavitation) was investigated in Rhapis excelsa (Palmae). Embolism was detected using measurements of xylem flow resistance in excised stems and petioles: a decrease in resistance after the removal of flow-impeding embolisms by a pressure treatment indicated their previous presence in the axis. Results suggested that Rhapis avoids serious damage from embolism in at least four ways. 1) Xylem pressure potentials reached embolism-inducing levels (c. -2.90 MPa) only during prolonged drought. 2) When embolism did occur, it was confined to leaf xylem; stem xylem, most critical to shoot survival, remained fully functional. This is due in part to hydraulic architecture: 70 to 85% of shoot xylem resistance is in the leaf, and thus xylem pressures are much lower in leaves than stems. 3) Even during prolonged drought, the amount of embolism is probably limited by complete stomatal closure, which occurred at xylem pressure potentials of -3.20 ± 0.18 MPa. 4) Embolism is potentially reversible during prolonged rains, since embolism dissolved within 5 h at zero pressure (atmospheric), and xylem pressure potential can reach zero during extended rain.

Stomatal control and the development of water deficit in Engelmann spruce seedlings during drought

1979 ◽  
Vol 9 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Merrill R. Kaufmann
Keyword(s):  
Flux Density ◽  
Stomatal Closure ◽  
Absolute Humidity ◽  
Pressure Potential ◽  
Evaporative Demand ◽  
Xylem Pressure ◽  
Full Sunlight ◽  
Engelmann Spruce ◽  
Xylem Pressure Potential ◽  
The Relationship

The effects of soil drying on water relations of Engelmann spruce (Piceaengelmannii Engelm.) were studied by withholding water from 4-year-old potted seedlings in full sunlight and under a shade screen transmitting 55–60% light. During a period of 2 months, xylem pressure potential, water vapor conductance, and transpirational flux density gradually declined compared with well watered controls, with drying being more rapid in full sunlight. As drying progressed, xylem pressure potential at 0 transpiration (predawn potential) decreased and the slope of the relationship between xylem pressure potential and transpirational flux density became more negative. Hysteresis in the relationship occurred when predawn xylem pressure potential was −6 bars (1 bar = 105 Pa) or lower. Needle conductance during daylight hours decreased as the absolute humidity difference from leaf to air increased but conductances were lower in September than in August for given humidity differences. Xylem pressure potentials between −15 and −19 bars had no clear effect on conductance in August but apparently caused significant stomatal closure in September. Because of humidity-induced stomatal closure, evaporative demand had little effect on transpirational flux density over a broad range of humidity gradient. Thus increased leaf-to-air vapor gradients for transpiration are not always accompanied by increased transpiration.

Changes in xylem pressure potential of red spruce seedlings treated with ozone and simulated acid rain

1989 ◽  
Vol 19 (9) ◽  
pp. 1200-1203 ◽  
Author(s):  
Bruce R. Roberts ◽  
William N. Cannon Jr.
Keyword(s):  
Acid Rain ◽  
Stomatal Closure ◽  
Turgor Pressure ◽  
Red Spruce ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
Acid Rainfall ◽  
Area Expansion ◽  
Air Control

Two-year-old containerized seedlings of red spruce (Picearubens Sarg.) were exposed for 8 weeks to charcoal-filtered air (control) or to 7 and 15 parts per hundred million (pphm) ozone (O3) alone and 15 pphm O3 in combination with simulated acid rainfall at pH 4.2 and 3.0 prior to measuring shoot xylem pressure potential. Pressure potential determinations for seedlings treated with O3 alone or O3 + acid rain were always higher (less negative) than similar determinations made on comparable seedlings grown in charcoal-filtered air. These results suggest that exposure to atmospheric deposition may affect xylem pressure potential indirectly by influencing transpirational water loss via stomatal closure and (or) reductions in leaf area expansion. Calculations of osmotic potential and turgor pressure suggest the possibility of some osmotic adjustment in response to deposition stress in this species.

Relation between root system size and water inflow capacity of Abiesamabilis growing in a subalpine forest

1985 ◽  
Vol 15 (4) ◽  
pp. 669-672 ◽  
Author(s):  
Robert O. Teskey ◽  
Charles C. Grier ◽  
Thomas M. Hinckley
Keyword(s):  
Root System ◽  
Stomatal Closure ◽  
System Size ◽  
Water Inflow ◽  
Subalpine Forest ◽  
Silver Fir ◽  
Small Contribution ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Xylem Pressure Potential

The water inflow capacity of the root systems of several 15- to 18-year-old Pacific silver fir (Abiesamabilis (Dougl.) Forbes) trees was investigated under field conditions. Severance of as much as one-third of the roots had no effect on xylem pressure potential, leaf conductance, or transpiration throughout the day following this treatment. Severance of more than half of the root system caused a decline in xylem pressure potential and partial stomatal closure. Measurements from trees which had been completely severed from their roots indicated that stored water made only a small contribution to the supply of water to the foliage of these trees. It was concluded that a balance did not exist between the capacity for water inflow and the rate of foliar water loss, at least in periods without drought. One advantage of excess absorptive capacity may be the ability to obtain adequate amounts of water from relatively small portions of the rooting zone.

Stomatal and photosynthetic response of sweet gum (Liquidambarstyraciflua) to flooding

1985 ◽  
Vol 15 (2) ◽  
pp. 371-375 ◽  
Author(s):  
S. R. Pezeshki ◽  
J. L. Chambers
Keyword(s):  
Stomatal Conductance ◽  
Water Status ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Controlled Environment ◽  
Photosynthetic Response ◽  
Short Term ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Xylem Pressure Potential

Effects of short-term flooding on stomatal conductance, net photosynthesis, and water status of sweet gum (Liquidambarstyraciflua L.) seedlings were studied under controlled environment conditions. Flooding for 9 days induced partial stomatal closure, resulting in significant declines in transpiration and net photosynthesis. The response to flooding was rapid with an average daily stomatal conductance declining from a preflood level of 0.43 cm•s−1 to 0.26 cm•s−1 by 24 h after flooding began (40% reduction). The average preflooding daily net photosynthesis was reduced from 13.7 to 10.2 mg CO2•dm−2•h−1 (25% reduction) during the same period and the average daily stomatal conductance and net photosynthesis for the 9th day of flooding were reduced by 70 and 77%, respectively, compared with preflood levels. The leaf xylem pressure potential measurements, however, indicated that water deficits did not develop as a result of flooding. Partial stomatal reopening 3 days after termination of flooding was noted with an average daily stomatal conductance approaching 63% of the preflood levels and an average daily net photosynthesis reaching 46% of its preflood levels. Maintenance of positive net photosynthesis throughout flooding, and partial stomatal and photosynthetic recovery following drainage may account for the tolerance of sweet gum seedlings to short-term flooding.

Soil temperature and drying cycle effects on water relations of Pinus radiata

1977 ◽  
Vol 55 (18) ◽  
pp. 2413-2418 ◽  
Author(s):  
Merrill R. Kaufmann
Keyword(s):  
Water Absorption ◽  
Flux Density ◽  
Pinus Radiata ◽  
Stomatal Closure ◽  
Atmospheric Conditions ◽  
Root Temperature ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
The Relationship

The influence of edaphic and atmospheric conditions on the development of plant water stress, water absorption by roots, and transpiration was studied with 2-year-old seedlings of Monterey pine (Pinus radiata D. Don). The slope of the relationship of xylem pressure potential to transpirational flux density was influenced by root temperature. Increased root resistances (separated from viscosity changes of water) occurred at root temperatures of 12 to 13 °C and became more limiting for water absorption at lower temperatures. Transpirational flux density was not affected by root temperature because xylem pressure potentials were not sufficiently low to close stomata. However, at the end of 9- and 12-day drying cycles, transpiration was lower than in well watered controls as a result of stomatal closure. The relationship between xylem pressure potential and transpiration exhibited hysteresis after 9 days of drying, but hysteresis was minimal upon rewatering or in unstressed control plants.

Critical Period of Weed Interference in Transplanted Tomatoes (Lycopersicon esculentum): Growth Analysis

Weed Science ◽  
1983 ◽  
Vol 31 (4) ◽  
pp. 476-481 ◽  
Author(s):  
Susan E. Weaver ◽  
Chin S. Tan
Keyword(s):  
Lycopersicon Esculentum ◽  
Critical Period ◽  
Growth Analysis ◽  
Canopy Temperature ◽  
Dry Weight ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Fruit Number ◽  
Weed Interference ◽  
Xylem Pressure Potential

The critical period of weed interference in transplanted tomatoes (Lycopersicon esculentumMill. 'Springset’) was from 28 to 35 days after transplanting. A single weeding during this period was sufficient to prevent yield reductions. A growth analysis revealed that significant differences in plant dry weight and fruit number between tomatoes from weed-free and weed-infested plots were not apparent until 56 to 70 days after transplanting. The shorter the initial weed-free period, or the longer weeds were allowed to remain in the plots before removal, the earlier reductions in tomato dry weight and fruit number appeared. Weed interference was due primarily to shading rather than water stress. Tomatoes from weed-infested plots had significantly lower stomatal conductances than those from weed-free plots, but did not differ in xylem-pressure potential or in canopy temperature. If tomatoes were kept weed-free for more than 28 days, or when weeds were present for less than 28 days after transplanting, stomatal conductances were not significantly reduced.

Comparative Studies in Selected Species of Eucalyptus Used in Rehabilitation of the Northern Jarrah Forest, Western Australia. I. Patterns of Xylem Pressure Potential and Diffusive Resistance of Leaves

1984 ◽  
Vol 32 (4) ◽  
pp. 367 ◽  
Author(s):  
IJ Colquhoun ◽  
RW Ridge ◽  
DT Bell ◽  
WA Loneragan ◽  
J Kuo
Keyword(s):  
Western Australia ◽  
Water Loss ◽  
Seasonal Patterns ◽  
Pressure Potential ◽  
Jarrah Forest ◽  
Eucalyptus Marginata ◽  
Xylem Pressure ◽  
Diffusive Resistance ◽  
Xylem Pressure Potential ◽  
The Impact

Land use which reduces tree canopy density and the impact of Phytophthora cinnamomi are believed to be altering the hydrological balance of parts of the northern jarrah forest, Western Australia. In the drier eastern zones of the forest, replacement plant communities must maintain the soil-salt-water balance to prevent significant increases in salinization of streams in water supply catchments. Daily and seasonal patterns of the diffusive resistance of leaves and xylem pressure potential were determined for the major natural dominant of the region, Eucalyptus marginata, and five other species of Eucalyptus used in rehabilitation. Three types of daily and seasonal patterns were observed. E. marginata and E. calophylla exhibited little stomatal control of water loss, and leaf resistances remained low throughout the study period (type 1). E. maculata, E. resinifera and E. saligna exhibited marked stomatal regulation during summer days when xylem pressure potentials fell below -2.O MPa (type 2). E. wandoo (type 3) also controlled water loss but developed xylem pressure potentials far lower than all other species tested (<-3.0 MPa). Although none of the species tested replicated the summer stomatal resistance and xylem pressure potential patterns of E. marginata, it is suggested that total annual water use should be examined before selecting the most appropriate species to rehabilitate disturbed sites in the eastern zones of the northern jarrah forest region.

Water relations of loblolly pine trees in southeastern Oklahoma following precommercial thinning

1990 ◽  
Vol 20 (9) ◽  
pp. 1508-1513 ◽  
Author(s):  
Bert M. Cregg ◽  
Thomas C. Hennessey ◽  
Philip M. Dougherty
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Loblolly Pine ◽  
Soil Water Potential ◽  
Basal Area ◽  
Leaf Conductance ◽  
Pressure Potential ◽  
Precommercial Thinning ◽  
Xylem Pressure ◽  
Xylem Pressure Potential

Xylem pressure potential, leaf conductance, transpiration, and soil moisture were measured during three summers following precommercial thinning of a 10-year-old stand of loblolly pine (Pinustaeda L.) in southeastern Oklahoma. The stand was thinned to three target basal-area levels: 5.8, 11.5, and 23 m2•ha−1 (control). Soil water potential increased significantly in response to thinning during the summer of each year studied. However, plant water relations were relatively unaffected by the treatments. Significant thinning effects on diurnal xylem pressure potential were observed on only 7 of 55 measurement periods. Treatment differences in conductance and transpiration observed during the first year of the study appeared to be related to differences in light interception and crown exposure. Regression analysis indicated response of leaf conductance and transpiration to predawn xylem pressure potential and vapor pressure deficit was not affected by the thinning treatments. Overall, the results of this study are consistent with a hypothesis in which transpiration, leaf area, and water potential interact to form a homeostatic relationship.

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