The Influence of Substrate Hydraulic Conductivity on Plant Water Status of an Ornamental Container Crop Grown in Suboptimal Substrate Water Potentials

Many soilless substrates are inefficient with regard to water (i.e., high porosity and low water holding capacity), which provides an excellent opportunity to increase water efficiency in containerized production. We suggest that increasing hydraulic conductivity in the dry range of substrate moisture content occurring during production can increase water availability, reduce irrigation volume, and produce high quality, marketable crops. Three substrates were engineered using screened pine bark (PB) and amending with either Sphagnum peatmoss or coir to have higher unsaturated hydraulic conductivity between water potentials of −100 and −300 hPa. There was no correlation between substrate unsaturated hydraulic conductivity and saturated hydraulic conductivity (r = 0.04, P = 0.8985). Established Hydrangea arborescens (L.) ‘Annabelle’ plants were grown in the three engineered and a conventional (control) PB substrates exposed to suboptimal irrigation levels (i.e., held at substrate water potentials between −100 and −300 hPa) for 32 days. The plants in the engineered substrates outperformed the control in every growth and morphological metric measured, as well as exhibiting fewer (or no) physiological drought stress indicators (i.e., vigor, growth, plant development, etc.) compared with the control. We observed increased vigor measures in plants grown in substrates with higher unsaturated hydraulic conductivity, as well as greater plant water uptake. The coir increased unsaturated hydraulic conductivity and provided an increased air space when incorporated into coarse bark vs. if peat was incorporated into bark at the same ratio by volume. Increasing PB hydraulic conductivity, through screening bark or amending bark with fibrous materials, in concert with low irrigations can produce marketable, vigorous crops while reducing water consumed and minimizing water wasted in ornamental container production.

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Soilless Substrate Hydrology Can Be Engineered to Influence Plant Water Status for an Ornamental Containerized Crop Grown within Optimal Water Potentials

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04251-17 ◽

2018 ◽

Vol 143 (4) ◽

pp. 268-281 ◽

Cited By ~ 2

Author(s):

Jeb S. Fields ◽

James S. Owen ◽

James E. Altland ◽

Marc W. van Iersel ◽

Brian E. Jackson

Keyword(s):

Hydraulic Conductivity ◽

Water Potential ◽

Loblolly Pine ◽

Water Status ◽

Crop Growth ◽

Plant Water Status ◽

Plant Water ◽

Eastern United States ◽

Water Potentials ◽

Soilless Substrate

Water-efficient soilless substrates need to be engineered to address diminishing water resources. Therefore, we investigated soilless substrates with varying hydrologies to determine their influence on crop growth and plant water status. Aged loblolly pine (Pinus taeda) bark was graded into four particle size fractions. The coarsest fraction was also blended with either sphagnum peat or coir at rates that mimic static physical properties of the unfractionated bark or conventional substrate used by specialty crop producers within the eastern United States. Hibiscus rosa-sinensis ‘Fort Myers’ plugs were established in each of the seven substrates and maintained at optimal substrate water potentials (−50 to −100 hPa). After a salable crop was produced 93 days after transplanting, substrate was allowed to dry until plants completely wilted. Crop morphology and water use was affected by substrate hydrology. Increased substrate unsaturated hydraulic conductivity (K) allowed for plants to access higher proportions of water and therefore increased crop growth. Maintaining optimal substrate water potential allowed plants to be produced with <18 L water. Measurements of plant water availability showed that the substrate water potential at which the crop ceases to withdraw water varied among substrates. Pore uniformity and connectivity could be increased by both fibrous additions and particle fractionation, which resulted in increased substrate hydraulic conductivity (Ks). Plants grown in substrates with higher hydraulic conductivities were able to use more water. Soilless substrate hydrology can be modified and used in concert with more efficient irrigation systems to provide more water sustainability in container crop systems.

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A Hydrological Study of a Subtropical Semiarid Forest of Acacia harpophylla F. Muell. Ex Benth. (Brigalow)

Australian Journal of Botany ◽

10.1071/bt9810311 ◽

1981 ◽

Vol 29 (3) ◽

pp. 311 ◽

Cited By ~ 14

Author(s):

BR Tunstall ◽

DJ Connor

Keyword(s):

Soil Water ◽

Water Status ◽

Water Storage ◽

Soil Water Storage ◽

Severe Drought ◽

Plant Water ◽

Evaporative Demand ◽

Water Potentials ◽

Plant Water Potential ◽

Stem Flow

Water input, soil water storage and plant water status were measured at monthly intervals over 2� years In a mature brigalow (Acacla harpophylla) forest. Redistribution of rainfall by the canopy was slight and stem flow averaged only 1.8%, but the direct loss of intercepted water accounted for 15% of the Annual ramfall In the wettest condltlon the soil stored 890 mm of water to a depth of 3 m The minimum sod water store measured under severe drought conditions was 840 mm when the dawn values of plant water potential were -6.8 MPa The soil water potentials below 1 m were consistently around -3.5 MPa due largely to high salt concentrations The tendency in a drying soil was towards a uniform profile of soil water potentlal, and soil water at depths below 1 m was extracted only when dawn plant water potentials were less than - 3.5 MPa Over monthly Intervals the maximum and minimum rates of evapotransplratlon were 3.3 and 0 .46 mm/d respectively, and the pattern of community water use was related to rainfall and not to potentlal evaporation. To survive in such an environment the plants develop and withstand extremely low water potentials associated wlth the low availability of water and the high evaporative demand.

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Dynamic aspects of plant water potential revealed by a microtensiometer

10.1101/2021.06.23.449675 ◽

2021 ◽

Author(s):

Vinay V Pagay

Keyword(s):

Water Potential ◽

Water Status ◽

Vapour Pressure Deficit ◽

Irrigation Scheduling ◽

Field Conditions ◽

Plant Water ◽

Water Potentials ◽

Cross Correlation Analysis ◽

Plant Water Potential ◽

Long Time

Water potential is a fundamental thermodynamic parameter that describes the activity of water. In this paper, we describe the continuous measurement of plant water potential, a reliable indicator of its water status, using a novel in situ sensor known as a microtensiometer in mature grapevines under field conditions. The microtensiometer operates on the principle of equilibration of water potentials of internal liquid water with an external vapour or liquid phase. We characterised the seasonal and diurnal dynamics of trunk water potentials (Ψtrunk) obtained from microtensiometers installed in two grapevine cultivars, Shiraz and Cabernet Sauvignon, and compared these values to pressure chamber-derived stem (Ψstem) and leaf (Ψleaf) water potentials as well as leaf stomatal conductance. Diurnal patterns of Ψtrunk matched those of Ψstem and Ψleaf under low vapour pressure deficit (VPD) conditions, but diverged under high VPD conditions. The highest diurnal values of Ψtrunk were observed shortly after dawn, while the lowest values were typically observed in the late afternoon. Differential responses of Ψtrunk to VPD were observed between cultivars, with Shiraz more sensitive than Cabernet to increasing VPD over long time scales, and both cultivars had a stronger VPD response than soil moisture response. On a diurnal basis, however, time cross correlation analysis revealed that Shiraz Ψtrunk lagged Cabernet Ψtrunk in response to changing VPD. Microtensiometers were shown to operate reliably under field conditions over several months. To be useful for irrigation scheduling of woody crops, new thresholds of Ψtrunk need to be developed.

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The Method of Plant Water Status Measurement in Sweet Potato (Ipomoea Batatas (L) Lam.)

Beccariana Botanical Research Bulletin ◽

10.30862/bbrp.v7i1.274 ◽

2010 ◽

Vol 7 (1) ◽

Author(s):

Saraswati Prabawardani

Keyword(s):

Water Content ◽

Sweet Potato ◽

Relative Water Content ◽

Water Status ◽

Plant Water Status ◽

Equilibration Time ◽

Plant Water ◽

Font Size ◽

Potato Leaf ◽

Relative Water

The measurement of plant water status such as leaf water potential (LWP) and leaf relative water content (RWC) is important part of understanding plant physiology and biomass production. Preliminary study was made to determine the optimum amount of leaf abrasion and equilibration time of sweet potato leaf inside the thermocouple psychrometer chambers. Based on the trial, the standard equilibration time curve of a Peltier thermocouple for sweet potato leaf was between 2 and 3 hours. To increase the water vapour conductance across the leaf epidermis the waxy leaf cuticle should be removed or broken by abrasion. The result showed that 4 times leaf rubbings was accepted as the most effective way to increase leaf vapour conductance of sweet potato in the psychrometer chambers. In calculating the leaf relative water content, unstressed water of sweet potato leaves require 4 hours imbibition, whereas water stressed of sweet potato leaves require 5 to 6 hours to reach the saturation time. Either leaf water potential or relative water content can be used as a parameter for plant water status in sweet potato.

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