Estimation of twig xylem water potential in young Douglas-fir trees

1984 ◽  
Vol 14 (4) ◽  
pp. 481-487 ◽  
Author(s):  
F. M. Kelliher ◽  
T. A. Black ◽  
A. G. Barr
Keyword(s):  
Water Potential ◽  
Root Zone ◽  
Water Pressure ◽  
Soil Water Potential ◽  
Douglas Fir ◽  
Logarithmic Function ◽  
Pressure Potential ◽  
Xylem Water Potential ◽  
The Difference ◽  
Chamber Measurements

Methodology, based on water flow theory, is described which can be used to estimate twig xylem water potential for 10–15 m tall Douglas-fir (Pseudotsugamenziesii) (Mirb.) Franco) trees. Using pressure chamber measurements, values of needle xylem water pressure potential were found to be similar to twig xylem water pressure potential. For root zone soil water potential (ψs) > −0.4 MPa, measured predawn total twig xylem water potential (ψTtx) of these Douglas-fir trees was significantly less than ψs. A transpiration rate (E) dependent single soil to twig liquid resistance (Rst) accounted for the difference between predawn ψTtx and ψs. For ψs > −0.4 MPa, during the daytime when E was high, Rst could be described by a logarithmic function of ψs. The effect of capacitance on twig xylem water potential (ψtx) was small. A model incorporating the transpiration dependent Rst accurately estimated the course of ψtx on a clear day when ψs was −0.04 MPa.

scholarly journals Root uptake under mismatched distributions of water and nutrients in the root zone

2020 ◽  
Author(s):  
Jing Yan ◽  
Nathaniel A. Bogie ◽  
Teamrat Ghezzehei
Keyword(s):  
Water Potential ◽  
Nutrient Availability ◽  
Nutrient Management ◽  
Root Zone ◽  
Soil Water Potential ◽  
Potential Gradient ◽  
Hydraulic Redistribution ◽  
Natural Environments ◽  
Water Release ◽  
Dry Soil

Abstract. Most plants derive their water and nutrient needs from soils, where the resources are often scarce, patchy, and ephemeral. In natural environments, it is not uncommon for plant roots to encounter mismatched patches of water-rich and nutrient-rich regions. Such an uneven distribution of resources necessitates plants to rely on strategies that allow them to explore and acquire nutrients from relatively dry patches. We conducted a laboratory study to provide a mechanistic understanding of the biophysical factors that enable this adaptation. We grew plants in split-root pots that permitted precisely controlled spatial distributions of resources. The results demonstrated that spatial mismatch of water and nutrient availability does not cost plant productivity compared to matched distributions. Specifically, we showed that nutrient uptake is not reduced by overall soil dryness, provided that the whole plant has access to sufficient water elsewhere in the root zone. Essential strategies include extensive root proliferation towards nutrient-rich dry soil patches that allows rapid nutrient capture from brief pulses. Using high-frequency water potential measurements, we also observed nocturnal water release by roots that inhabit dry and nutrient-rich soil patches. Soil water potential gradient is the primary driver of this transfer of water from wet to dry soil parts of the root zone, which is commonly known as hydraulic redistribution (HR). The occurrence of HR prevents the soil drying from approaching the permanent wilting point, and thus supports root functions and enhance nutrient availability. Our results indicate that roots facilitate HR by increasing root-hair density and length and deposition of organic coatings that alter water retention. Therefore, we conclude that biologically-controlled root adaptation involves multiple strategies that compensate for nutrient acquisition under mismatched resource distributions. Based on our findings, we proposed a nature-inspired nutrient management strategy for significantly curtailing water pollution from intensive agricultural systems.

Needle water potential and soil-to-foliage flow resistance during soil drying: a comparison of Douglas-fir, western hemlock, and mountain hemlock

1985 ◽  
Vol 15 (1) ◽  
pp. 185-188 ◽  
Author(s):  
T. M. Ballard ◽  
M. G. Dosskey
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Flow ◽  
Flow Resistance ◽  
Soil Water Potential ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Soil Drying ◽  
Experimental Conditions ◽  
Needle Water Potential

Needle water potential in western and mountain hemlock falls as the soil dries, but under our experimental conditions, it remained stable in Douglas-fir. Resistance to water flow from soil to foliage is higher for the hemlocks and increases more steeply as the soil dries. These findings physically account for the observation that water uptake is reduced relatively more for the hemlocks than for Douglas-fir, as soil water potential declines.

Characteristics of stomatal diffusion resistance in a Douglas fir forest exposed to soil water deficits

1977 ◽  
Vol 7 (4) ◽  
pp. 595-604 ◽  
Author(s):  
C. S. Tan ◽  
T. A. Black ◽  
J. U. Nnyamah
Keyword(s):  
Soil Water ◽  
Soil Water Potential ◽  
High Stress ◽  
Vapour Pressure Deficit ◽  
Douglas Fir ◽  
Diffusion Resistance ◽  
Total Water ◽  
Pressure Potential ◽  
Relationship Of ◽  
The Relationship

As part of a 2-year study of the effect of thinning on evapotranspiration in Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), the relationship between stomatal diffusion resistance (rs) and environmental variables were studied. Research was conducted in an unthinned stand (1840 stems ha−1) with negligible undergrowth and a thinned stand (840 stems ha−1) with substantial salal (Gaultheriashallon Pursh) undergrowth. During the daytime rs was mainly related to the soil water potential (ψs) and the vapour pressure deficit (v.p.d.) of the canopy air. Daytime values of rs for Douglas fir ranged from 2 to 60 s cm−1 for values of v.p.d. between 4 and 24 mb (4 and 24 × 102 Pa) and values of ψs between 0 and −12.5 bars (0 and −12.5 × 105 Pa). Although increasing rs was usually associated with decreasing pressure potential of the twig xylem (ψt), increasing rs appeared to be associated with increasing ψt when the v.p.d. was high. Stress history was found to cause a shift in the relationship of rs to ψt, but had little effect on the relationship of rs to v.p.d. and ψs. Daytime values of rs for salal ranged from 2 to 45 s cm−1. This stomatal behaviour suggests that as the soil dried out, salal transpiration accounted for an increasing fraction of the total water loss by the thinned stand.

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.

Effects of disrupting stem sapwood water conduction on the water status in Douglas-fir crowns

1985 ◽  
Vol 15 (5) ◽  
pp. 982-985 ◽  
Author(s):  
H. Brix ◽  
A. K. Mitchell
Keyword(s):  
Water Potential ◽  
Water Flow ◽  
Leaf Water Potential ◽  
Water Status ◽  
Soil Water Potential ◽  
Douglas Fir ◽  
Leaf Water ◽  
Cross Sectional ◽  
Breast Height ◽  
Water Conduction

The sapwood cross-sectional area at breast height was reduced by 0 (control), 42, 69, and 100%, in 36-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees to study treatment effects on the water status in the crowns. Only the complete removal of breast-height sapwood affected the leaf water potential which decreased rapidly the 1st day, but then changed little for the next 38 days varying only from −2.3 to −2.6 MPa. Water use for those trees was limited to that stored above breast height, primarily in stem sapwood, and amounted to approximately 45 L. This corresponded to 6.5 mm of precipitation or 4% of potential transpiration. The finding that leaf water potential was not affected by partial sapwood reduction but rather by changes in soil water potential suggests that resistance to water flow in stems was small compared with that in other parts of the water-flow pathways of soil and trees.

Thinning and nitrogen fertilization effects on soil and tree water stress in a Douglas-fir stand

1986 ◽  
Vol 16 (6) ◽  
pp. 1334-1338 ◽  
Author(s):  
H. Brix ◽  
A. K. Mitchell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Nitrogen Fertilization ◽  
Soil Water Potential ◽  
Early Morning ◽  
Douglas Fir ◽  
Fertilization Effect ◽  
Use Efficiency ◽  
Soil Water Conditions ◽  
Fertilization Effects

Soil and tree water potentials were studied over a 10-year period in a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand that was treated when 24 years old with different thinning and nitrogen fertilization regimes. Throughout the 10-year period, thinning increased the soil water potential during the dry summer periods (July–September) by as much as 1 MPa both with and without fertilization. Fertilization effect on soil water potential was slight and only apparent in the latter part of the study in spite of large increases in leaf area (50% after 7 years) possibly because of better stomatal control of water loss. Fertilization increased water use efficiency. The favorable soil water conditions produced by thinning led to improved shoot water potential only during predawn and early morning. Removal of understory in a thinned and fertilized plot did not affect soil or shoot water potential.

Roles of weathered bedrock and soil in seasonal water relations of Pinus Jeffreyi and Arctostaphylos patula

2001 ◽  
Vol 31 (11) ◽  
pp. 1947-1957 ◽  
Author(s):  
K R Hubbert ◽  
J L Beyers ◽  
R C Graham
Keyword(s):  
Water Potential ◽  
Sierra Nevada ◽  
Water Relations ◽  
Soil Water Potential ◽  
Pinus Jeffreyi ◽  
Pressure Potential ◽  
Available Water ◽  
Jeffrey Pine ◽  
Plant Available Water ◽  
Arctostaphylos Patula

In the southern Sierra Nevada, California, relatively thin soils overlie granitic bedrock that is weathered to depths of several metres. The weathered granitic bedrock is porous and has a plant-available water capacity of 0.124 m3·m–3, compared with 0.196 m3·m–3 for the overlying soil. Roots confined within bedrock joint fractures access this rock-held water, especially during late summer when overlying soils are dry. We sought to determine seasonal soil and bedrock water changes in a Jeffrey pine (Pinus jeffreyi Grev & Balf.) plantation and to examine concurrent effects on the water relations of Jeffrey pine and greenleaf manzanita (Arctostaphylos patula Greene). In 1996, plant-available water in the 75 cm thick soil was depleted by late June, with soil water potential (ψsoil) <–2.2 MPa, but below 75 cm, bedrock water potential (ψbedrock) was still > –2.2 MPa. Thus, the bedrock, not the soil, supplied water to plants for the remainder of the dry season. Higher values of, and smaller fluctuations in, seasonal predawn pressure potential (ψpredawn) for Jeffrey pine indicated that it is deeply rooted, whereas active roots of greenleaf manzanita were interpreted to be mostly within the upper 100 cm. The extra rooting volume supplied by weathered bedrock is especially important to pine relative to manzanita.

scholarly journals Effects of Mulch and Irrigation System on Sweet Onion: I. Bolting, Plant Growth, and Bulb Yield and Quality

2004 ◽  
Vol 129 (2) ◽  
pp. 218-224 ◽  
Author(s):  
Juan C. Díaz-Pérez ◽  
William M. Randle ◽  
George Boyhan ◽  
Ronald W. Walcott ◽  
David Giddings ◽  
...  
Keyword(s):  
Water Potential ◽  
Nitrogen Content ◽  
Wheat Straw ◽  
Root Zone ◽  
Irrigation System ◽  
Soil Water Potential ◽  
Bare Soil ◽  
Plastic Film ◽  
Wheat Straw Mulch ◽  
Bulb Yield

Sweet onions (Allium cepa L.) are typically grown on bare soil and irrigated with high-pressure systems such as sprinklers or center-pivots. The objective of this study was to determine the effects of irrigation system and mulch on bolting, bulb yield and bulb quality over 3 years. The experimental design was a split plot, where the main plot was irrigation system (drip or sprinkler) and the subplot was the type of mulch (bare soil, black plastic film or wheat straw). The results showed that individual bulb weight and bulb yields under drip irrigation were similar to those under sprinkler irrigation. Plants grown on bare soil had the highest total yield during the three seasons and among the highest marketable yield. There were no consistent differences in the bulb number or yield of plants on plastic film mulch compared to those of plants on wheat straw mulch. Plants on wheat straw mulch had reduced foliar nitrogen content. Variability in yields among mulches and seasons was partly explained by changes in seasonal root zone temperature and soil water potential. Total and marketable yields and weight of individual bulbs increased with increasing root zone temperatures up to an optimum at 15.8 °C, followed by reductions in yields and individual bulb weight at >15.8 °C. Onion bolting increased with decreasing foliage nitrogen content, with plants on wheat straw having the highest bolting incidence. Bolting also increased with decreasing root zone temperatures for the season. Total and marketable yields increased with decreasing mean seasonal soil water potential down to -30 kPa. Irrigation system and mulches had no consistent effect on the soluble solids content or pungency of onion bulbs.

Sign in / Sign up

Export Citation Format

Share Document