Effects of drying soils on survival of young Piceaglauca seedlings

1982 ◽  
Vol 12 (4) ◽  
pp. 1006-1009 ◽  
Author(s):  
E. C. Tear ◽  
K. O. Higginbotham ◽  
J. M. Mayo
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Water Loss ◽  
Growing Season ◽  
Combined Effects ◽  
Pressure Potential ◽  
Greenhouse Soil ◽  
Soil Mixture ◽  
Xylem Pressure ◽  
Xylem Pressure Potential

Drought stress is often suggested as a factor preventing successful field establishment of seedlings of white spruce (Piceaglauca (Moench) Voss) during their first growing season. In this study the combined effects of water stress and seedbed type on 1- and 3-month-old seedlings were examined. Shoot xylem pressure potential decreased to −1.5 MPa in seedlings grown in a greenhouse soil mixture in 9.5 days but took 18.5 days to reach this level in peat. Mortality reached 100% for 1-month-old seedlings grown in greenhouse mix 11 days after watering ceased, while it took 23 days to reach this level in peat. Shoot xylem pressure potentials can be used to predict mortality potential on the two seedbed types. Three-month-old seedlings on either seedbed survived for at least 31 days without watering, indicating development of capability for control of water loss with time.

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.

Influence of artificial shade on water stress of containerized ponderosa pine seedlings

1977 ◽  
Vol 7 (3) ◽  
pp. 537-540 ◽  
Author(s):  
Bruce A. Buchanan ◽  
Michael F. Davault ◽  
James T. Fisher
Keyword(s):  
New Mexico ◽  
Water Stress ◽  
Ponderosa Pine ◽  
Relative Water Content ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Sacramento Mountains ◽  
Pine Seedlings ◽  
Xylem Pressure Potential ◽  
Relative Water

Artificially shaded and unshaded containerized Pinusponderosa Laws, seedlings were planted in the Sacramento Mountains of southern New Mexico on July 29, 1975. Xylem pressure potential (Pstem) and relative water content (RWC) were measured four times per day from August 1 to 16, 1975. Shading had little effect on RWC but significantly increased Pstem; midafternoon (1530 hours, MDST) increase averaged 2 bars (1 bar = 105 Pa). During the study RWC ranged from 86 to 94% and Pstem ranged from −4 to −10 bars. At the end of September no mortality had occurred in either treatment.

Measurement of water stress in subalpine trees: effects of temporary tissue storage methods and needle age

1982 ◽  
Vol 12 (4) ◽  
pp. 969-972 ◽  
Author(s):  
Merrill R. Kaufmann ◽  
Gary L. Thor
Keyword(s):  
Water Stress ◽  
Conifer Species ◽  
Pressure Potential ◽  
Tissue Storage ◽  
Storage Tissue ◽  
Tissue Samples ◽  
Needle Age ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
Storage Methods

Water stress of subalpine conifer species may be measured with the pressure chamber after several hours of tissue storage. Tissue samples stored in cool, humid vials exhibited very little change in xylem pressure potential over a 4-h period. However, xylem pressure potential declined steadily when a source of water vapor was not available. Xylem pressure potentials of current-year and 1-year-old needles of lodgepole pine (Pinuscontorta var. latifolia Engelm.) were slightly lower than those of older needles.

scholarly journals Drought Stress Increases Densities but Not Populations of Two-spotted Spider Mite on Buddleia davidii `Pink Delight'

HortScience ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 280-282 ◽  
Author(s):  
Jeffrey H. Gillman ◽  
Mark W. Rieger ◽  
Michael A. Dirr ◽  
S. Kristine Braman
Keyword(s):  
Drought Stress ◽  
Leaf Area ◽  
Spider Mite ◽  
Shoot Growth ◽  
Population Densities ◽  
Pressure Potential ◽  
Xylem Pressure ◽  
Xylem Pressure Potential ◽  
Buddleia Davidii ◽  
Two Spotted Spider Mite

Two experiments were conducted to determine the effect of drought stress on the susceptibility of Buddleia davidii Franch. `Pink Delight' to the two-spotted spider mite (Tetranychus urticae Koch). In the first experiment, drought stress was imposed by withholding water until predawn xylem pressure potential fell below -1 MPa. Shoot growth was 75% less in drought-stressed than in nonstressed plants. Mite population densities were not affected, but noninfested leaf area was 14% higher, and degree of mite damage was lower, in nonstressed plants. Evidently, the greater amount of new growth in nonstressed plants leads to lower spider mite densities by diluting populations. In a second experiment, nonstressed B. davidii `Pink Delight' plants were watered every 1 to 2 days and drought-stressed plants were watered every 3 days. Spider mite populations were monitored by sampling newly expanded and mature foliage. Mite populations on mature foliage were not affected by stress, but stressed plants grew less and had larger spider mite populations on their newly expanded foliage than did nonstressed 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.

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.

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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