scholarly journals Arbuscular Mycorrhiza Symbiosis Enhances Water Status and Soil-Plant Hydraulic Conductance Under Drought

2021 ◽  
Vol 12 ◽  
Author(s):  
Mohanned Abdalla ◽  
Mutez Ali Ahmed

Recent studies have identified soil drying as a dominant driver of transpiration reduction at the global scale. Although Arbuscular Mycorrhiza Fungi (AMF) are assumed to play a pivotal role in plant response to soil drying, studies investigating the impact of AMF on plant water status and soil-plant hydraulic conductance are lacking. Thus, the main objective of this study was to investigate the influence of AMF on soil-plant conductance and plant water status of tomato under drought. We hypothesized that AMF limit the drop in matric potential across the rhizosphere, especially in drying soil. The underlying mechanism is that AMF extend the effective root radius and hence reduce the water fluxes at the root-soil interface. The follow-up hypothesis is that AMF enhance soil-plant hydraulic conductance and plant water status during soil drying. To test these hypotheses, we measured the relation between transpiration rate, soil and leaf water potential of tomato with reduced mycorrhiza colonization (RMC) and the corresponding wild type (WT). We inoculated the soil of the WT with Rhizophagus irregularis spores to potentially upsurge symbiosis initiation. During soil drying, leaf water potential of the WT did not drop below −0.8MPa during the first 6days after withholding irrigation, while leaf water potential of RMC dropped below −1MPa already after 4days. Furthermore, AMF enhanced the soil-plant hydraulic conductance of the WT during soil drying. In contrast, soil-plant hydraulic conductance of the RMC declined more abruptly as soil dried. We conclude that AMF maintained the hydraulic continuity between root and soil in drying soils, hereby reducing the drop in matric potential at the root-soil interface and enhancing soil-plant hydraulic conductance of tomato under edaphic stress. Future studies will investigate the role of AMF on soil-plant hydraulic conductance and plant water status among diverse plant species growing in contrasting soil textures.

1989 ◽  
Vol 16 (3) ◽  
pp. 241 ◽  
Author(s):  
NZ Saliendra ◽  
FC Meinzer

Stomatal conductance, leaf and soil water status, transpiration, and apparent root hydraulic conductance were measured during soil drying cycles for three sugarcane cultivars growing in containers in a greenhouse. At high soil moisture, transpiration and apparent root hydraulic conductance differed considerably among cultivars and were positively correlated, whereas leaf water potential was similar among cultivars. In drying soil, stomatal and apparent root hydraulic conductance approached zero over a narrow (0.1 MPa) range of soil water suction. Leaf water potential remained nearly constant during soil drying because the vapor phase conductance of the leaves and the apparent liquid phase conductance of the root system declined in parallel. The decline in apparent root hydraulic conductance with soil drying was manifested as a large increase in the hydrostatic pressure gradient between the soil and the root xylem. These results suggested that control of stomatal conductance in sugarcane plants exposed to drying soil was exerted primarily at the root rather than at the leaf level.


2021 ◽  
Vol 118 (23) ◽  
pp. e2008276118
Author(s):  
Piyush Jain ◽  
Weizhen Liu ◽  
Siyu Zhu ◽  
Christine Yao-Yun Chang ◽  
Jeff Melkonian ◽  
...  

Leaf water potential is a critical indicator of plant water status, integrating soil moisture status, plant physiology, and environmental conditions. There are few tools for measuring plant water status (water potential) in situ, presenting a critical barrier for developing appropriate phenotyping (measurement) methods for crop development and modeling efforts aimed at understanding water transport in plants. Here, we present the development of an in situ, minimally disruptive hydrogel nanoreporter (AquaDust) for measuring leaf water potential. The gel matrix responds to changes in water potential in its local environment by swelling; the distance between covalently linked dyes changes with the reconfiguration of the polymer, leading to changes in the emission spectrum via Förster Resonance Energy Transfer (FRET). Upon infiltration into leaves, the nanoparticles localize within the apoplastic space in the mesophyll; they do not enter the cytoplasm or the xylem. We characterize the physical basis for AquaDust’s response and demonstrate its function in intact maize (Zea mays L.) leaves as a reporter of leaf water potential. We use AquaDust to measure gradients of water potential along intact, actively transpiring leaves as a function of water status; the localized nature of the reporters allows us to define a hydraulic model that distinguishes resistances inside and outside the xylem. We also present field measurements with AquaDust through a full diurnal cycle to confirm the robustness of the technique and of our model. We conclude that AquaDust offers potential opportunities for high-throughput field measurements and spatially resolved studies of water relations within plant tissues.


2020 ◽  
Author(s):  
Piyush Jain ◽  
Weizhen Liu ◽  
Siyu Zhu ◽  
Jeff Melkonian ◽  
Duke Pauli ◽  
...  

AbstractLeaf water potential is a critical indicator of plant water status, integrating soil moisture status, plant physiology, and environmental conditions. There are few tools for measuring plant water status (water potential) in situ, presenting a critical barrier for the development of appropriate phenotyping (measurement) methods for crop development and modeling efforts aimed at understanding water transport in plants. Here, we present the development of an in situ, minimally-disruptive hydrogel nanoreporter (AquaDust) for measuring leaf water potential. The gel matrix responds to changes in water potential in its local environment by swelling; the distance between covalently linked dyes changes with the reconfiguration of the polymer, leading to changes in the emission spectrum via Fluorescence Resonance Energy Transfer (FRET). Upon infiltration into leaves, the nanoparticles localize within the apoplastic space in the mesophyll; they do not enter the cytoplast or the xylem. We characterize the physical basis for AquaDust’s response and demonstrate its function in intact maize (Zea mays L.) leaves as a reporter of leaf water potential. We use AquaDust to measure gradients of water potential along intact, actively transpiring leaves as a function of water status; the localized nature of the reporters allows us to define a hydraulic model that distinguishes resistances inside and outside the xylem. We also present field measurements with AquaDust through a full diurnal cycle to confirm the robustness of the technique and of our model. We conclude that AquaDust offers potential opportunities for high-throughput, field measurements and spatially resolved studies of water relations within plant tissues.


Dendrobiology ◽  
2021 ◽  
Vol 85 ◽  
pp. 39-50
Author(s):  
Henrik Sjöman ◽  
Anna Levinsson ◽  
Tobias Emilsson ◽  
Aida Ibrahimova ◽  
Valida Alizade ◽  
...  

The urban environment is stressful and trees experience multiple stresses, including drought, flooding, and extreme heat, all of which are likely to increase under future climate warming and increasing urbanisation. In the selection of tree species to maximise ecosystem services, tolerance to site characteristics such as flooding and severe drought is of critical importance. This study evaluated the suitability of a rare species, Alnus subcordata C.A. Mey (Caucasian alder) from the Hyrcanian forests of southern Azerbaijan,for its functionality as an urban tree. A total of 48 pot-grown, two-year-old saplings of A. subcordata were tested in a greenhouse experiment using a complete randomised block design. Each block contained four replicates of three treatments (waterlogging, drought, control), with 16 plants per treatment. Height differences between treatments were measured, and water status was estimated by determination of midday leaf water potential (ΨL) and stomatal conductance (gs). To estimate drought tolerance reaction in the treatments, leaf water potential at turgor loss (ΨP0) was used together with broken-stick modelling of water status over time. There was a significant difference in tree height between the different treatments. In the drought treatment, A. subcordata plants showed no height increase, while plants in both the waterlogged and control treatments increased in height during the nine-week experiment. Over 63 days of flooding, plant water status was slightly more negative in the waterlogging treatment, but did not deviate essentially from the control. In the drought treatment, plant water status rapidly deviated from the control. There was a significant differencein ΨP0 between treatments, with drought-treated plants showing the lowest value (−2.31 MPa).This study demonstrated that A. subcordata has limited tolerance to drought and seems to rely more on waterloss-avoiding strategies. However, the species may be usable at periodically waterlogged sites, due to its high tolerance to flooding. It could therefore be recommended for wet urban environments and stormwater management facilities, for which reliable guidance on suitable trees is currently lacking.


2011 ◽  
Vol 38 (6) ◽  
pp. 523 ◽  
Author(s):  
Salah Elsayed ◽  
Bodo Mistele ◽  
Urs Schmidhalter

Leaf water potential (LWP) is an important indicator of plant water status. However, its determination via classical pressure-chamber measurements is tedious and time-consuming. Moreover, such methods cannot easily account for rapid changes in this parameter arising from changes in environmental conditions. Spectrometric measurements, by contrast, have the potential for fast and non-destructive measurements of plant water status, but are not unproblematic. Spectral characteristics of plants vary across plant development stages and are also influenced by environmental factors. Thus, it remains unclear whether changes in leaf water potential per se can reliably be detected spectrometrically or whether such measurements also reflect autocorrelated changes in the leaf water content (LWC) or the aerial plant biomass. We tested the accuracy of spectrometric measurements in this context under controlled climate chamber conditions in series of six experiments that minimised perturbing influences but allowed for significant changes in the LWP. Short-term exposure of dense stands of plants to increasing or decreasing artificial light intensities in a growth chamber more markedly decreased LWP than LWC in both wheat and maize. Significant relationships (R2-values 0.74–0.92) between LWP and new spectral indices ((R940/R960)/NDVI; R940/R960) were detected with or without significant changes in LWC of both crop species. The exact relationships found, however, were influenced strongly by the date of measurement or water stress induced. Thus, global spectral relationships measuring LWP probably cannot be established across plant development stages. Even so, spectrometric measurements supplemented by a reduced calibration dataset from pressure chamber measurements might still prove to be a fast and accurate method for screening large numbers of diverse lines.


2010 ◽  
Vol 20 (3) ◽  
pp. 585-593 ◽  
Author(s):  
Ana Centeno ◽  
Pilar Baeza ◽  
José Ramón Lissarrague

Limited water supply in arid and semiarid Mediterranean environments demands improving irrigation efficiency. The purpose of this study was to determine a functional relationship between soil water availability and wine grape (Vitis vinifera) water status to determine a threshold value of soil matric potential to trigger irrigation. Seasonal trends of soil water potential, leaf water potential, and stomatal conductance (gS) of ‘Tempranillo’ wine grape were determined in two deficit irrigation treatments replenishing 45% and 30% of the reference evapotranspiration, and in a third non-irrigated treatment during 2001 and 2002. Soil water potential was measured with granular matrix soil moisture sensors placed at 0.3 m (Ψ0.3), 0.6 m (Ψ0.6), and 1.2 m (Ψ1.2) depths. The sensors at 0.3 m depth quickly responded to irrigation by increasing Ψ0.3 levels. At the 0.6 m depth, Ψ0.6 progressively decreased, showing significant differences between T1 and the rest of the treatments, while no significant differences in Ψ1.2 were found. All relationships between profile soil matric potential and leaf water potential and gS were highly correlated. After integrating our data with previous studies, we suggest a whole profile soil water potential value of –0.12 MPa as threshold to trigger irrigation and avoid severe water stress during berry growth.


2000 ◽  
Vol 40 (5) ◽  
pp. 687 ◽  
Author(s):  
A. L. Bernardi

The water potentials of canola branches and leaves were compared using a pressure chamber to determine whether they produced similar results. This study also investigated the magnitude of errors in the water status of canola resulting from re-cutting the branches, and the effects of delaying readings. The use of branches containing pods or pods and flowers/buds gave very good correlation with leaves. As this is the area of greatest photosynthesis and transpiration from mid-flowering, it provides an easily obtainable source material close to the main growth areas to measure plant water potential. Storage of both leaves and stems before measurement is an acceptable procedure if a large number of samples are required to be completed or portable equipment is not available provided precautions are taken to prevent moisture loss. Re-cutting the branch leads to lower water potential and should be avoided.


1980 ◽  
Vol 16 (1) ◽  
pp. 21-27 ◽  
Author(s):  
D. Kumar ◽  
Larry L. Tieszen

SUMMARYExperiments were carried out to relate soil moisture to leaf water potential (Ψ1), and to determine the effects of varying Ψ1, on leaf conductances and photosynthesis in coffee. Stomatal conductance was maximum at 0900 h, but plants growing in drier soil showed marked mid-day stomatal closure. After 1500 h, stomata began closing although plant water status improved. Photosynthesis in relation to changing Ψ1 appeared to exhibit roughly three different rates. At the fixed experimental temperature (25°C) low Ψ1 reduced photosynthesis throughits influence on stomata, but under field conditions low Ψ1 and an accompanying rise in temperature could lower the rate by lowering both mesophyll and stomatal conductances.


Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2121
Author(s):  
Cristina Romero-Trigueros ◽  
Jose María Bayona Gambín ◽  
Pedro Antonio Nortes Tortosa ◽  
Juan José Alarcón Cabañero ◽  
Emilio Nicolás Nicolás

Citrus species are frequently subjected to water and saline stresses worldwide. We evaluated the effects of diurnal changes in the evaporative demands and soil water contents on the plant physiology of grapefruit and mandarin crops under saline reclaimed (RW) and transfer (TW) water conditions, combined with two irrigation strategies, fully irrigated (fI) and non-irrigated (nI). The physiological responses were different depending on the species. Grapefruit showed an isohydric pattern, which restricted the use of the leaf water potential (Ψl) as a plant water status indicator. Its water status was affected by salinity (RW) and water stress (nI), mainly as the combination of both stresses (RW-nI); however, mandarin turned out to be relatively more tolerant to salinity and more sensitive to water stress, mainly because of its low hydraulic conductance (K) levels, showing a critical drop in Ψl that led to severe losses of root–stem (Kroot–stem) and canopy (Kcanopy) hydraulic conductance in TW-nI. This behavior was not observed in RW-nI because a reduction in canopy volume as an adaptive characteristic was observed; thus, mandarin exhibited more anisohydric behavior compared to grapefruit, but isohydrodynamic since its hydrodynamic water potential gradient from roots to shoots (ΔΨplant) was relatively constant across variations in stomatal conductance (gs) and soil water potential. The gs was considered a good plant water status indicator for irrigation scheduling purposes in both species, and its responses to diurnal VPD rise and soil drought were strongly correlated with Kroot–stem. ABA did not show any effect on stomatal regulation, highlighting the fundamental role of plant hydraulics in driving stomatal closure.


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