The Water Relations of Tree Seedlings II. Transpiration in Relation to Soil Water Potential

Plants of Lupinus cosentinii Guss. cv. Eregulla were grown in a sandy soil in large containers in a glasshouse and exposed to drought by withholding water. Under these conditions stomatal closure had previously been shown to be initiated before a significant reduction in leaf water potential was detected. In the experiments reported here, no significant changes were found in water potential or turgor pressure of roots or leaves when a small reduction in soil water potential was induced which led to a 60% reduction in leaf conductance. The decrease in leaf conductance and root water uptake closely paralleled the fraction of roots in wet soil. By applying observed data of soil water and root characteristics, and root water uptake for whole pots in a single-root model, the average water potential at the root surface was calculated. Potential differences for water transport in the soil-plant system, and the resistances to water flow were estimated using the 'Ohm's Law' analogy for water transport. Soil resistance was negligible or minor, whereas the root resistance accounted for 61-72% and the shoot resistance accounted for about 30% of the total resistance. The validity of the measurements and calculations is discussed and the possible role of root- to-shoot communication raised.

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Water relations of winter wheat: 2. Soil water relations

The Journal of Agricultural Science ◽

10.1017/s0021859600056665 ◽

1978 ◽

Vol 91 (1) ◽

pp. 103-116 ◽

Cited By ~ 68

Author(s):

P. J. Gregory ◽

M. McGowan ◽

P. V. Biscoe

Keyword(s):

Winter Wheat ◽

Water Potential ◽

Soil Water ◽

Water Relations ◽

Unit Length ◽

Soil Water Potential ◽

Rooting Depth ◽

Wheat Crop ◽

Deep Roots ◽

Volumetric Soil Water Content

SummaryVolumetric soil water content and soil water potential were measured beneath a winter wheat crop during the 1975 growing season. Almost no rain fell between mid-May and mid-July and the soil dried continuously until the potential was less than – 20 bars to a depth of 80 cm. Evaporation was separated from drainage by denning an ‘effective rooting depth’ at which the hydraulic gradient was zero.Rates of water uptake per unit length of root (inflow) were calculated for the whole soil profile and for individual soil layers. Generally, inflow decreased throughout the period of measurement from a maximum of 2·5 × 10–3 to a minimum of 0·66 × 10–3 ml water/cm root/day. Values in individual layers were frequently higher than the mean inflow and the importance of a few deep roots in taking up water during a dry season is emphasized. A similar correlation between inflow and soil water potential was found to apply for the 0–30 cm and 30–60 cm layers during the period of continual soil drying. This relationship represents the maximum inflow measured at a given soil water potential; actual inflow at any particular time depends upon the interrelationship of atmospheric demand, soil water potential and the distribution of root length in the soil.

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Eucalyptus sp. seedling response to potassium fertilization and soil water.

Ciência Florestal ◽

10.5902/19805098510 ◽

2008 ◽

Vol 18 (1) ◽

pp. 47 ◽

Cited By ~ 6

Author(s):

Paulo César Teixeira ◽

José Leonardo Moraes Gonçalves ◽

José Carlos Arthur Junior ◽

Cleci Dezordi

Keyword(s):

Water Potential ◽

Soil Water ◽

Leaf Area ◽

Water Deficit ◽

Water Relations ◽

Transpiration Rate ◽

Dry Matter ◽

Soil Water Potential ◽

Eucalyptus Grandis ◽

Eucalyptus Urophylla

A considerable portion of Brazil‘s commercial eucalypt plantations is located in areas subjected to periods of water deficit and grown in soils with low natural fertility, particularly poor in potassium. Potassium is influential in controlling water relations of plants. The objective of this study was to verify the influence of potassium fertilization and soil water potential (Ψw) on the dry matter production and on water relations of eucalypt seedlings grown under greenhouse conditions. The experimental units were arranged in 4x4x2 randomized blocks factorial design, as follow: four species of Eucalyptus (Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus camaldulensis and hybrid Eucalyptus grandis x Eucalyptus urophylla), four dosages of K (0, 50, 100 and 200 mg dm-3) and two soil water potentials (-0.01MPa and -0.1 MPa). Plastic containers with 15 cm diameter and 18 cm height, with Styrofoam base, containing 3.0 dm3 of soil and two plants per container were used. Soil water potential was kept at -0.01MPa for 40 days after seeding. Afterward, the experimental units were divided into two groups: in one group the potential was kept at -0.01MPa, and in the other one, at -0.10 MPa. Soil water potential was controlled gravimetrically twice a day with water replacement until the desired potential was reestablished. A week before harvesting, the leaf water potential (Ψ), the photosynthetic rate (A), the stomatal conductance (gs) and the transpiration rate were evaluated. The last week before harvesting, the mass of the containers was recorded daily before watering to determine the consumption of water by the plants. After harvesting, total dry matter and leaf area were evaluated. The data were submitted to analysis of variance, to Tukey's tests and regression analyses. The application of K influenced A, gs and the transpiration rate. Plants deficient in K showed lower A and higher gs and transpiration rates. There were no statistical differences in A, gs and transpiration rates in plants with and without water deficit. The addition of K reduced the consumption of water per unit of leaf area and, in general, plants submitted to water deficit presented a lower consumption of water.

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Spatial and temporal heterogeneity of light and soil water along a terra firme transect in Amazonian Ecuador: effects on tree seedling survivorship, growth, and allocation

Canadian Journal of Forest Research ◽

10.1139/x11-168 ◽

2012 ◽

Vol 42 (1) ◽

pp. 203-206 ◽

Cited By ~ 8

Author(s):

Randall W. Myster

Keyword(s):

Water Potential ◽

Soil Water ◽

Leaf Area ◽

Soil Water Potential ◽

Forest Understory ◽

Spatial And Temporal Variation ◽

Tree Seedlings ◽

Temporal Heterogeneity ◽

Tree Seedling ◽

Terra Firme

To better understand the availability of plant resources on the forest floor in the Amazon and also to show the effect of their heterogeneity on tree seedlings, I described the spatial and temporal variation of light and soil water along a 100 m transect in a terra firme forest for 6 months and recorded responses of three tree species planted on that transect after 1 year’s growth. I found that (i) the spatial heterogeneity across the transect was greater than the temporal heterogeneity at any given microsite on the transect for both light and water and there was a positive correlation between them, (ii) Couepia obovata Ducke, the largest seeded and the only subcanopy tree, survived the best and showed both the largest relative height growth rate (RHGR) and the largest specific leaf area (SLA), while among the two early successional trees, Tapirira guianensis J.B. Aublet had the largest leaf area ratio (LAR) and the largest leaf mass ratio (LMR) and Duguethia spixiana Mart. had the largest root to shoot ratio (RTOS), (iii) for T. guianensis, SLA increased with increasing light and soil water potential predicted both increasing LMR and decreasing RTOS with increasing soil water, and (iv) soil water potential could also predict increasing LAR with increasing water for D. spixiana and, for C. obovata, soil water potential predicted more survivorship, LMR, and RHGR but less RTOS, all with increasing soil water. I conclude that some subcanopy trees may survive and grow more than open-canopy trees when presented with water stress in the forest understory and that within the ranges of light and soil water sampled here, plants responded more to spatial variation in water compared with light.

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Water Relations and Abscisic Acid in Pot-grown Strawberry Plants under Limited Irrigation

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.134.5.574 ◽

2009 ◽

Vol 134 (5) ◽

pp. 574-580 ◽

Cited By ~ 6

Author(s):

Nauja Lisa Jensen ◽

Christian R. Jensen ◽

Fulai Liu ◽

Karen K. Petersen

Keyword(s):

Abscisic Acid ◽

Water Potential ◽

Soil Water ◽

Water Relations ◽

Root Zone ◽

Water Vapor Pressure ◽

Xylem Sap ◽

Soil Water Potential ◽

Significant Difference ◽

Irrigation Treatments

We investigated the effect of full irrigation (FI), deficit irrigation (DI), partial root zone drying (PRD), and nonirrigation (NI) on soil and plant–water relations, leaf stomatal conductance (gs), and abscisic acid (ABA) concentration in the xylem sap ([ABA]xylem) of pot-grown strawberry plants (Fragaria ×ananassa cv. Honeoye) in a greenhouse experiment. The DI and PRD treatments, irrigated with 70% of the volume of FI, reduced soil water content (θ), whereas crown water potential (ψcrown), leaf water potential (ψleaf), and gs were only significantly reduced from 11 to 15 days after initiation of irrigation treatments. Although [ABA]xylem was not significantly affected by the DI and PRD treatments, the NI plants increased [ABA]xylem, which coincided with decreased ψcrown, ψleaf, and gs 3 to 4 days after withholding irrigation. When ψcrown dropped below a critical value of −0.4 MPa, [ABA]xylem was linearly correlated with ψcrown. The gs tended to decrease as a function of [ABA]xylem, but gs was also affected by the water vapor pressure deficit (VPD) of the air. It is concluded that we did not observe a significant difference between strawberry plants grown in PRD and DI because ψcrown had to be below −0.4 MPa and soil water potential (ψsoil) had to be below −0.25 MPa before [ABA]xylem increased, these values were only reached toward the end of the experimental period (11–15 days after initiation of irrigation treatments).

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Effect of Soil Water Potential of Two Soils on Soybean Emergence 1

Agronomy Journal ◽

10.2134/agronj1979.00021962007100060021x ◽

1979 ◽

Vol 71 (6) ◽

pp. 980-982 ◽

Cited By ~ 3

Author(s):

L. G. Heatherly ◽

W. J. Russell

Keyword(s):

Water Potential ◽

Soil Water ◽

Soil Water Potential

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Simulating sunflower canopy temperatures to infer root-zone soil water potential

Agricultural and Forest Meteorology ◽

10.1016/0168-1923(84)90007-8 ◽

1984 ◽

Vol 31 (1) ◽

pp. 69-78 ◽

Cited By ~ 8

Author(s):

Bhaskar J. Choudhury ◽

Sherwood B. Idso

Keyword(s):

Water Potential ◽

Soil Water ◽

Root Zone ◽

Soil Water Potential

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A Data-Driven Method for the Temporal Estimation of Soil Water Potential and Its Application for Shallow Landslides Prediction

Water ◽

10.3390/w13091208 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1208

Author(s):

Massimiliano Bordoni ◽

Fabrizio Inzaghi ◽

Valerio Vivaldi ◽

Roberto Valentino ◽

Marco Bittelli ◽

...

Keyword(s):

Machine Learning ◽

Water Potential ◽

Soil Water ◽

Temporal Trends ◽

Soil Water Potential ◽

Shallow Landslides ◽

Water Dynamics ◽

Data Driven ◽

Machine Learning Techniques ◽

Physically Based

Soil water potential is a key factor to study water dynamics in soil and for estimating the occurrence of natural hazards, as landslides. This parameter can be measured in field or estimated through physically-based models, limited by the availability of effective input soil properties and preliminary calibrations. Data-driven models, based on machine learning techniques, could overcome these gaps. The aim of this paper is then to develop an innovative machine learning methodology to assess soil water potential trends and to implement them in models to predict shallow landslides. Monitoring data since 2012 from test-sites slopes in Oltrepò Pavese (northern Italy) were used to build the models. Within the tested techniques, Random Forest models allowed an outstanding reconstruction of measured soil water potential temporal trends. Each model is sensitive to meteorological and hydrological characteristics according to soil depths and features. Reliability of the proposed models was confirmed by correct estimation of days when shallow landslides were triggered in the study areas in December 2020, after implementing the modeled trends on a slope stability model, and by the correct choice of physically-based rainfall thresholds. These results confirm the potential application of the developed methodology to estimate hydrological scenarios that could be used for decision-making purposes.

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