Soil Water Status Affects the Stomata1

1986 ◽  
Vol 13 (4) ◽  
pp. 459 ◽  
Author(s):  
T Gollan ◽  
RA Richards ◽  
HM Rawson ◽  
JB Passioura ◽  
DA Johnson ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status ◽  
Stomatal Closure ◽  
Leaf Conductance ◽  
Pressure Chamber ◽  
Pneumatic Pressure ◽  
Soil Water Status

Wheat and sunflower were grown in pots that could be enclosed in a pressure chamber, with the shoot in a cuvette. Applying an appropriate pneumatic pressure to the roots enabled the leaves to be kept fully turgid despite any drying of the soil. The leaf conductance of plants was followed while the soil dried. Remarkably, this conductance fell with falling soil water content no matter whether the leaves were kept fully turgid or not. It is concluded that the roots sensed the drying of the soil and sent a message to the leaves which induced stomatal closure.

scholarly journals Predicting Soil Water Content on Rainfed Maize through Aerial Thermal Imaging

2021 ◽  
Vol 3 (4) ◽  
pp. 942-953
Author(s):  
Matheus Gabriel Acorsi ◽  
Leandro Maria Gimenez
Keyword(s):  
Linear Regression ◽  
Spatial Variability ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status ◽  
Canopy Temperature ◽  
Crop Water ◽  
Soil Water Status ◽  
Physical Attributes

Restrictions on soil water supply can dramatically reduce crop yields by affecting the growth and development of plants. For this reason, screening tools that can detect crop water stress early have been long investigated, with canopy temperature (CT) being widely used for this purpose. In this study, we investigated the relationship between canopy temperature retrieved from unmanned aerial vehicles (UAV) based thermal imagery with soil and plant attributes, using a rainfed maize field as the area of study. The flight mission was conducted during the late vegetative stage and at solar noon, when a considerable soil water deficit was detected according to the soil water balance model used. While the images were being taken, soil sampling was conducted to determine the soil water content across the field. The sampling results demonstrated the spatial variability of soil water status, with soil volumetric water content (SVWC) presenting 10.4% of variation and values close to the permanent wilting point (PWP), reflecting CT readings that ranged from 32.8 to 40.6 °C among the sampling locations. Although CT correlated well with many of the physical attributes of soil that are related to water dynamics, the simple linear regression between CT and soil water content variables yielded coefficients of determination (R2) = 0.42, indicating that CT alone might not be sufficient to predict soil water status. Nonetheless, when CT was combined with some soil physical attributes in a multiple linear regression, the prediction capacity was significantly increased, achieving an R2 value = 0.88. This result indicates the potential use of CT along with certain soil physical variables to predict crop water status, making it a useful tool for studies exploring the spatial variability of in-season drought stress.

Leaf Gas Exchange and Water Relations of Lupins and Wheat. I. Shoot Responses to Soil Water Deficits

1989 ◽  
Vol 16 (5) ◽  
pp. 401 ◽  
Author(s):  
IE Henson ◽  
CR Jensen ◽  
NC Turner
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Turgor Pressure ◽  
Leaf Conductance ◽  
Leaf Water

The effects of a progressive increase in soil water deficit on the leaf conductance and gas exchange of lupin (Lupinus cosentinii) and wheat (Triticum aestivum) were investigated in pot experiments in a temperature-regulated glasshouse, using a coarse, sandy soil characteristic of the Western Australian wheatbelt. Transpiration rates decreased rapidly in both species after water was withheld, mainly as a result of stomatal closure. Photosynthesis declined also, but to a lesser extent than conductance. Leaf extension in lupin was equally as sensitive to a decrease in leaf water potential and soil water potential as stomatal conductance. Stomatal closure served to maintain the water potential of lupin leaves to within 0.1 MPa of that of control (watered) plants as the soil water content decreased from 0.14 to 0.06 m3 m-3 and as the leaf conductance and the relative transpiration rate fell to less than 50% of control values. Maintenance of leaf water potential with decreasing soil water content and stomatal conductance was less evident in wheat. In both lupin and wheat, leaf conductance decreased linearly with soil water content and curvilinearly with bulk soil matric potential, indicating that water uptake was restricted at similar water contents and matric potentials in both species. Diurnal measurements on lupin indicated a substantial reduction in stomatal conductance after water was withheld, even when the leaf water potential at midday was reduced by only 0.1 MPa and no change could be detected in the bulk leaf turgor pressure. Conductance in lupin was reduced even though the soil matric potential decreased in only part of the rooting zone. This, together with the absence of any significant change in the leaf water potential, turgor pressure, or relative water content in lupin during the initial stages of stomatal closure, suggests that a soil or root factor initiates the reduction in leaf conductance - and hence regulates the shoot water status - in response to soil drying.

scholarly journals Comparison of neutron moisture gauges with nonnuclear methods to measure field soil water status

1992 ◽  
Vol 49 (spe) ◽  
pp. 111-121 ◽  
Author(s):  
C. Kirda ◽  
K. Reichardt
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Spatial Dependence ◽  
Water Status ◽  
Field Soil ◽  
Soil Water Status ◽  
Neutron Moisture ◽  
Level Of Significance ◽  
Space Dependence

The neutron moisture gauge is compared with the gravimetric-core soil sampling technique, tensiometers and resistance blocks in relation to stability, Held variability, spatial dependence and number of samples needed at a given level of significance. The variance of field water content measurements with neutron moisture gauges is lower than that of the gravimetric sampling, which therefore requires 2 to 6 times as many samples as the number of measuring sites of the gauges to attain the same level of significance. The space dependence of the measurements made with the subsurface gauge varied depending on the average field soil water content. No space dependence was evident when the water content was lower than 0.2 cm³.cm-3 (50% saturation). Measurements with the tensiometers and resistance blocks manifested no spatial dependence and therefore randomly selected measuring sites can be adapted to Held research work where these methods are to be utilized. Soil water content measurements estimated with neutron moisture gauges showed well defined temporal stability (i.e., the lowest, average and the highest soil water content measurements occur at the same field site) which implies that soil water status of an entire field can be assessed with measurements limited to few locations. Measurements with both tensiometers and the resistance blocks are time variant (i.e., the site giving field average water content changes spatially in time) owing to their relatively smaller measuring domains (i.e., scale of the area which can be represented by a single measurement) as compared to neutron gauges. Therefore it is not possible to define the measuring sites of the tensiometers and resistance blocks as to assess soil water status of the entire field, as it could be done with the neutron gauge.

scholarly journals 278 Gas Exchange and Water Relations of Diverse Tall Fescue Cultivars in Response to Drought Stress

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 490C-490
Author(s):  
Bingru Huang ◽  
Hongwen Gao
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Physiological Factors ◽  
Relative Water

To investigate shoot physiological responses to drought stress of six tall fescue (Festuca arundinacea) cultivars representing several generations of turfgrass improvement, forage-type `Kentucky-31', turf-type `Phoenix', `Phoenix', and `Houndog V', and dwarf-type `Rebel Jr` and `Bonsai' were grown in well-watered or drying soil for 35 days in a greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivars and physiological factors. Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Falcon II', `Houndog V', and `Kentucky-31' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn was due mostly to internal water deficit and stomatal closure under short-term or mild drought-stress conditions. After a prolonged period of drought (35 DOT), higher Pn in `Falcon II', `Houndog V', and `Kentucky-31' could be attributed to their higher Fv/Fm.

Young lime tree evapotranspiration measurements in lysimeters with automated irrigation

2021 ◽  
Author(s):  
Ana belén Mira-García ◽  
Juan Vera ◽  
Wenceslao Conejero ◽  
Mª Carmen Ruiz-Sánchez
Keyword(s):  
Gas Exchange ◽  
Water Balance ◽  
Water Content ◽  
Soil Water ◽  
Real Time ◽  
Soil Water Content ◽  
Water Status ◽  
Soil Water Balance ◽  
Crop Evapotranspiration ◽  
Lime Tree

<p>Lime tree growing area is increasing in Mediterranean temperate regions. In these areas, climate change scenario is expected to raise air temperature and water shortages. Such scenario requires new approaches to implement a precision irrigation in agriculture. In order to use water more efficiently, it becomes necessary to accurately determining the crop water needs, which are estimated by crop evapotranspiration computations (ETc). In this study the ETc of young lime trees grown under Mediterranean conditions were determined using the soil water balance method. For this purpose, two-year old lime trees (Citrus latifolia Tan., cv. Bearss) grafted on C. macrophylla rootstock were cultivated in pot-lysimeters, equipped with capacitance and granular matric sensors for real-time monitoring of the soil water status. Irrigation, drainage, and pot weight were also monitored continuously. All measurements were integrated into a telemetry platform. Agro-meteorological variables, plant water status (stem (Ψ<sub>stem</sub>) and leaf (Ψ<sub>leaf</sub>) water potentials), and leaf gas exchange parameters (stomatal conductance (g<sub>s</sub>) and net photosynthesis (P<sub>n</sub>)) were measured. Along the experiment, an automated irrigation protocol based on volumetric soil water content (θ<sub>v</sub>) threshold values were programmed, guaranteeing an adequate lime tree water status. Irrigation dose was calculated based on a feed-back strategy maintaining θ<sub>v </sub>within 30% management allowed depletion.</p><p>During the experimental period, the lime trees were well irrigated as revealed midday Ψ<sub>stem </sub>values that were maintained above -0.8 MPa. Also, the mean seasonal values of ≈ 7 µmol m<sup>−2</sup> s<sup>−1</sup> and 80 mmol m<sup>−2</sup> s<sup>−1</sup>, for P<sub>n</sub> and g<sub>s</sub>, respectively, indicated optimal gas exchange values. The computed water balance parameters yielded values for the crop evapotranspiration from 0.25<sup></sup>to 2.56 mm day<sup>-1</sup>, in winter and summer months, respectively, with maximum values in July when evaporative demand conditions were the highest. This soil water balance was daily validated by the pot weight balance through the year.</p><p>In conclusion, the automated irrigation of young potted lime trees, using soil water content as a control system variable, has ensured an adequate lime tree water status. A simple, robust weighing/drainage lysimeter, with real-time monitoring of the soil water balance parameters, has been proved practical and economical tool for crop evapotranspiration measurements.</p><p>Acknowledgments: This work was funded by Spanish Agencia Estatal de Investigación (PID2019-106226RB-C2-1/AEI/10.13039/501100011033) and Fundación Séneca, Región de Murcia (19903/GERM/15) projects.</p>

Hydraulic conductance of intact plants of two contrasting sorghum lines, SC15 and SC1205

2013 ◽  
Vol 40 (7) ◽  
pp. 730 ◽  
Author(s):  
Sunita Choudhary ◽  
Thomas R. Sinclair ◽  
P. V. Vara Prasad
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Use ◽  
Hydraulic Conductance ◽  
Leaf Conductance ◽  
Soil Drying ◽  
Water Deficits ◽  
Intact Plants ◽  
The Impact

Low plant hydraulic conductance has been hypothesised as an approach to decrease the rate of soil water use, resulting in soil water conservation for use during late season water deficits. The impact of leaf hydraulic conductance (Kleaf) on water use characteristics was explored by comparing two sorghum (Sorghum bicolor (L.) Moench) genotypes that had been found to differ in Kleaf. Genotype SC15 had a much lower leaf conductance than genotype SC1205. Four sets of experiments were undertaken to extend the comparison to the impact of differences in Kleaf on the plant water budget. (1) Measurements of hydraulic conductance of intact plants confirmed that leaf conductance of SC15 was lower than that of SC1205. (2) The low leaf conductance of SC15 was associated with a decrease in transpiration during soil drying at a higher soil water content than that of SC1205. (3) SC15 had a restricted transpiration rate at vapour pressure deficits (VPD) above 2.1 kPa, whereas SC1205 did not. (4) Treatment with aquaporin inhibitors showed substantial differences in the sensitivity of the transpiration response between the genotypes. These results demonstrated that low Kleaf in SC15 was associated with conservative water use by restricting transpiration at higher soil water content during soil drying and under high VPD. Tests with inhibitors indicate that these differences may be linked to differences between their aquaporin populations. The differences between the two genotypes indicated that the traits exhibited by SC15 would be desirable in environments where soil water deficits develop.

scholarly journals Physiological Responses of Diverse Tall Fescue Cultivars to Drought Stress

HortScience ◽  
1999 ◽  
Vol 34 (5) ◽  
pp. 897-901 ◽  
Author(s):  
Bingru Huang ◽  
Hongwen Gao
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Drought Resistance ◽  
Tall Fescue ◽  
Physiological Responses ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Limiting Factors

Drought is among the most limiting factors for turfgrass growth. Understanding genetic variations and physiological mechanisms in turfgrass drought resistance would facilitate breeding and management programs to improve drought resistance. The experiment was designed to investigate shoot physiological responses of six tall fescue (Festuca arundinacea Schreb.) cultivars representing several generations of turfgrass improvement to drought stress. Grasses were grown in well-watered or drying (nonirrigated) soil for 35 days in the greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivar and physiological factors. The values of Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Houndog V', `Kentucky-31', and `Falcon II' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn resulted mainly from internal water deficit and stomatal closure under mild drought-stress conditions. After a prolonged period of drought stress (35 DOT), `Falcon II', `Houndog V', and `Kentucky-31' maintained higher Pn than did `Rebel Jr', `Bonsai', and `Phoenix', which could be attributed to their higher Fv/Fm. This study demonstrated variation in drought resistance among tall fescue cultivars, which was related to their differential responses in photosynthetic capacity and water relations.

Water Content of Sludge-injected Soil Growing Wheat

1983 ◽  
Vol 10 (4) ◽  
pp. 337-342 ◽  
Author(s):  
James M. Stone ◽  
M. B. Kirkham
Keyword(s):  
Triticum Aestivum ◽  
Sewage Sludge ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status ◽  
Growing Season ◽  
Inorganic Fertilizer ◽  
Digested Sludge

Municipalities are injecting sewage sludge into soil—as a means of disposal, to avoid the problems of odours, pests, and runoff, and to avert public disapproval associated with application on the surface. The sludge injected is mainly liquid (94–99%), but its effect on soil-water content in the field has not been sufficiently reported on. The objective of the project here described was to determine, in a subhumid region, whether the liquid in sludge changed the water status of soil compared with that of soil with inorganic fertilizer. In addition, growth of Winter Whẽat (Triticum aestivum L. em. Thell.), grown on dryland and fertilized with the sludge or with inorganic fertilizer, was monitored. The experiment, carried out during the 1980–81 growing-season, was done at the Manhattan, Kansas, sewage-sludge farm, where aerobically digested sludge has been injected since 1976.

The paradox of defoliation: Declining tree water status with increasing soil water content

2020 ◽  
Vol 290 ◽  
pp. 108025 ◽  
Author(s):  
Lorena Balducci ◽  
Angelo Fierravanti ◽  
Sergio Rossi ◽  
Sylvain Delzon ◽  
Louis De Grandpré ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status
Sign in / Sign up

Export Citation Format

Share Document