The influence of alkalinity and water stress on the stomatal conductance, photosynthetic rate and growth of Lupinus angustifolius L. and Lupinus pilosus Murr.

1999 ◽  
Vol 39 (4) ◽  
pp. 457 ◽  
Author(s):  
C. Tang ◽  
N. C. Turner
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Root Growth ◽  
Soil Water ◽  
Photosynthetic Rate ◽  
Sandy Soil ◽  
Lupinus Angustifolius ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Lupinus Pilosus

A glasshouse experiment examined the effect of water stress on the growth of Lupinus angustifolius L. and Lupinus pilosus Murr. grown on an acid sandy soil, a limed sandy soil and an alkaline clay soil. Decreasing soil water content decreased the stomatal conductance and photosynthetic rate, and reduced plant growth. The responses of both species to water stress were generally similar in the sand and limed soils, but in the alkaline soil, L. angustifolius grown with limited water had markedly lower conductances and photosynthetic rates than the plants in the other soils at equivalent soil water contents. In adequately watered plants, the lupin species differed substantially in their growth response to soil types. Whereas the growth of L. pilosus was unaffected, the shoot dry weight of L. angustifolius grown on the limed and alkaline soils for 25–44 days was reduced by 32–54 and 44–86%, respectively, compared with the growth in the acid soil. The poor growth of L. angustifolius appeared to be primarily due to its poor root growth. In the alkaline soil, water stress reduced rather than stimulated root growth. The results suggest that, in the field, the limited root growth of L. angustifolius on alkaline soils will exacerbate water deficits when the topsoil dries out in the latter part of the season.

scholarly journals Effects of soil water depletion on the water relations in tropical kudzu

1999 ◽  
Vol 34 (7) ◽  
pp. 1151-1157
Author(s):  
Adaucto Bellarmino de Pereira-Netto ◽  
Antonio Celso Novaes de Magalhães ◽  
Hilton Silveira Pinto
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Content ◽  
Soil Water ◽  
Cover Crop ◽  
Soil Water Depletion ◽  
Pueraria Phaseoloides ◽  
Water Depletion ◽  
Relative Water ◽  
Dry Soil

Tropical kudzu (Pueraria phaseoloides (Roxb.) Benth., Leguminosae: Faboideae) is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC), stomatal conductance (g) and temperature (T L) in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O).g (dry soil)-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC). The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L) rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

Assessment of the effect of mycorrhizal fungi on drought tolerance of conifer seedlings

1991 ◽  
Vol 69 (8) ◽  
pp. 1764-1771 ◽  
Author(s):  
C. David Boyle ◽  
Klaus E. Hellenbrand
Keyword(s):  
Water Stress ◽  
Root Growth ◽  
Water Potential ◽  
Photosynthetic Rate ◽  
Mycorrhizal Fungi ◽  
Pure Culture ◽  
Black Spruce ◽  
Jack Pine ◽  
Conifer Seedlings ◽  
Low Water Potential

Methods were evaluated for comparing the potential of mycorrhizal fungi to increase the performance of conifer seedlings during water stress. The ability of five fungi to grow in pure culture under conditions of low water potential was tested. The same fungal isolates were then assessed in association with jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) seedlings. Mycorrhizal seedlings were subjected to known water stress by exposing their roots to a solution of polyethylene glycol or were planted into systems that allowed the simulation of a drought cycle in a forest soil. The apparent photosynthetic rate or the apparent photosynthetic rate and shoot and root growth were used as measures of seedling performance in the two systems. Fungi that grew well in pure culture under low water potential generally also increased the performance of black spruce. The ability of some fungi to form rhizomorphs extending into the mineral soil layer or to stimulate root growth also correlated with increased performance of black spruce. In contrast, under the experimental conditions used, jack pine showed good performance independent of mycorrhizal status. It is concluded that the screening methods used have value in selecting plant–fungus combinations that have potential to increase performance of conifer seedlings under drought stress. Key words: ectomycorrhizae, conifers, drought, Pinus, Picea.

scholarly journals Reassessing the Role of Potassium in Tomato Grown with Water Shortages

Horticulturae ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 20
Author(s):  
Anna De Luca ◽  
Mireia Corell ◽  
Mathilde Chivet ◽  
M. Angeles Parrado ◽  
José M. Pardo ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Photosynthetic Rate ◽  
Yield Reduction ◽  
Higher Plant ◽  
Water Shortages ◽  
Great Yield ◽  
Fruit Setting ◽  
K Concentration ◽  
Biomass Partition

Potassium (K) is closely related to plant water uptake and use and affects key processes in assimilation and growth. The aim of this work was to find out to what extent K supply and enhanced compartmentation might improve water use and productivity when tomato plants suffered from periods of water stress. Yield, water traits, gas exchange, photosynthetic rate and biomass partition were determined. When plants suffered dehydration, increasing K supply was associated with reduction in stomatal conductance and increased water contents, but failed to protect photosynthetic rate. Potassium supplements increased shoot growth, fruit setting and yield under water stress. However, increasing the K supply could not counteract the great yield reduction under drought. A transgenic tomato line with enhanced K uptake into vacuoles and able to reach higher plant K contents, still showed poor yield performance under water stress and had lower K use efficiency than the control plants. With unlimited water supply (hydroponics), plants grown in low-K showed greater root hydraulic conductivity than at higher K availability and stomatal conductance was not associated with leaf K concentration. In conclusion, increasing K supply and tissue content improved some physiological features related to drought tolerance but did not overcome yield restrictions imposed by water stress.

Photosynthesis and Stomatal-Conductance Responses of Johnsongrass (Sorghum halepense) to Water Stress

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 635-639 ◽  
Author(s):  
Bryan L. Stuart ◽  
Daniel R. Krieg ◽  
John R. Abernathy
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Osmotic Potential ◽  
Grain Filling ◽  
Leaf Temperature ◽  
Sorghum Halepense

The influence of water stress on johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA] physiology was evaluated in a semiarid environment. Stomatal conductance of johnsongrass responded to more negative leaf water potential and increasing leaf temperature. The sensitivity of the leaf temperature effect was dependent on the soil water content. At low soil water content, conductance was limited by low water potential, and increasing leaf temperature had little effect. Conductance of CO2was related to net photosynthesis in a curvilinear manner, with conductance levels greater than 0.3 mol·m-2· s-1being in excess of that necessary for maximum photosynthesis. At both high conductance levels and low levels associated with increased water stress, intercellular CO2concentration increased, indicating nonstomatal limitations to photosynthesis. Decreased osmotic potential provided the highest correlation with the linear decline of photosynthetic rate as stress intensified. The expression of osmotic adjustment in johnsongrass is reported during grain filling. Plants in the milkdough stage of grain filling had approximately 0.3 MPa lower osmotic potential at any relative water content than those at anthesis.

scholarly journals Towards a unified theory of plant photosynthesis and hydraulics

2020 ◽  
Author(s):  
Jaideep Joshi ◽  
Ulf Dieckmann ◽  
Iain Colin Prentice
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
Plant Responses ◽  
Plant Hydraulics ◽  
Plant Photosynthesis ◽  
Embolism Resistance

<p>Increasing frequencies and intensities of droughts are projected for many regions of the Earth. Water stress leads to a decline in the gross primary productivity (GPP) of plants. Plant responses to water stress vary with timescale, and plants adapted to different environments differ in their responses. Here, we present a unified theory of plant photosynthesis and plant hydraulics, which explains a wide range of observed plant responses to developing water stress.</p><p>Our theory is based on the least-cost hypothesis of Prentice et al. (2014). By integrating plant hydraulics into the least-cost framework, we attempt to improve upon the model of GPP by Wang et al. (2017), which accurately predicts the responses of global GPP to temperature, elevation, and vapour pressure deficit, but overestimates GPP under water-stressed conditions. Our model has three key ingredients. (1) The aforementioned least-cost framework, in which optimal stomatal conductance minimizes the summed costs of maintaining transpiration, the photosynthetic machinery, and the hydraulic pathways, including the potential costs of repairing embolized xylem. We also test a closely related maximum-benefit framework, in which optimal stomatal conductance maximizes the net benefit from assimilation while accounting for these summed costs, and obtain comparable results. (2) A trait-dependent model of water flow through the plant stem, in which water flow is limited by the conductivity (K<sub>s</sub>) and embolism resistance (P<sub>50</sub>) of the hydraulic pathway. At the shortest timescale, water stress causes stomatal closure to an extent that the transpiration demand determined by the vapour pressure deficit at the leaf surface is matched by the water supply through the stem. (3) A short-term response of photosynthetic capacity (V<sub>cmax</sub>) to soil moisture, through which the potential V<sub>cmax</sub> acclimates to prevailing daytime conditions to equalize carboxylation-limited and electron-transport-limited photosynthesis rates (A<sub>c</sub> and A<sub>j</sub>), while the realized values of V<sub>cmax</sub>, A<sub>c</sub>, and A<sub>j</sub> are reduced from their potential values by a factor dependent on the leaf water potential and the leaf embolism resistance.</p><p>We estimate the parameters of our model using published data from short-term and long-term dry-down experiments. The key predictions of our model are as follows: (1) GPP declines with decreasing soil water potential and drops to zero soon after the soil water potential crosses P<sub>50</sub>; (2) soil-to-leaf water potential difference remains relatively constant under developing water stress; (3) functional forms describing the declines in stomatal conductance, V<sub>cmax</sub>, and GPP with soil water potential are consistent with observations; and (4) decreased photosynthetic capacity (V<sub>cmax</sub>) recovers (in the long term) if the plant increases its Huber value (e.g., by shedding leaves), increases its conductivity (e.g., by growing wider new vessels), or decreases its height growth (e.g., by reducing allocation to growth). Our theory provides a potential way of integrating trait-based responses of plants to water stress into global vegetation models, and should therefore help to improve predictions of the global carbon and water cycles in a changing environment.</p><p>References: [1] Prentice IC, et al. <em>Ecology letters</em> 17.1 (2014): 82-91.  [2] Wang H, et al. <em>Nature Plants</em> 3.9 (2017): 734.</p>

scholarly journals Comparison of root water uptake models in simulating CO<sub>2</sub> and H<sub>2</sub>O fluxes and growth of wheat

2020 ◽  
Vol 24 (10) ◽  
pp. 4943-4969
Author(s):  
Thuy Huu Nguyen ◽  
Matthias Langensiepen ◽  
Jan Vanderborght ◽  
Hubert Hüging ◽  
Cho Miltin Mboh ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Root Growth ◽  
Water Content ◽  
Soil Water ◽  
Water Uptake ◽  
Coupled Model ◽  
Hydraulic Conductance ◽  
Root Water Uptake ◽  
Whole Plant ◽  
Hydraulic Signaling

Abstract. Stomatal regulation and whole plant hydraulic signaling affect water fluxes and stress in plants. Land surface models and crop models use a coupled photosynthesis–stomatal conductance modeling approach. Those models estimate the effect of soil water stress on stomatal conductance directly from soil water content or soil hydraulic potential without explicit representation of hydraulic signals between the soil and stomata. In order to explicitly represent stomatal regulation by soil water status as a function of the hydraulic signal and its relation to the whole plant hydraulic conductance, we coupled the crop model LINTULCC2 and the root growth model SLIMROOT with Couvreur's root water uptake model (RWU) and the HILLFLOW soil water balance model. Since plant hydraulic conductance depends on the plant development, this model coupling represents a two-way coupling between growth and plant hydraulics. To evaluate the advantage of considering plant hydraulic conductance and hydraulic signaling, we compared the performance of this newly coupled model with another commonly used approach that relates root water uptake and plant stress directly to the root zone water hydraulic potential (HILLFLOW with Feddes' RWU model). Simulations were compared with gas flux measurements and crop growth data from a wheat crop grown under three water supply regimes (sheltered, rainfed, and irrigated) and two soil types (stony and silty) in western Germany in 2016. The two models showed a relatively similar performance in the simulation of dry matter, leaf area index (LAI), root growth, RWU, gross assimilation rate, and soil water content. The Feddes model predicts more stress and less growth in the silty soil than in the stony soil, which is opposite to the observed growth. The Couvreur model better represents the difference in growth between the two soils and the different treatments. The newly coupled model (HILLFLOW–Couvreur's RWU–SLIMROOT–LINTULCC2) was also able to simulate the dynamics and magnitude of whole plant hydraulic conductance over the growing season. This demonstrates the importance of two-way feedbacks between growth and root water uptake for predicting the crop response to different soil water conditions in different soils. Our results suggest that a better representation of the effects of soil characteristics on root growth is needed for reliable estimations of root hydraulic conductance and gas fluxes, particularly in heterogeneous fields. The newly coupled soil–plant model marks a promising approach but requires further testing for other scenarios regarding crops, soil, and climate.

scholarly journals On the Treatment of Soil Water Stress in GCM Simulations of Vegetation Physiology

2021 ◽  
Vol 9 ◽  
Author(s):  
P. L. Vidale ◽  
G. Egea ◽  
P. C. McGuire ◽  
M. Todt ◽  
W. Peters ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Land Surface ◽  
Spatiotemporal Variability ◽  
Climate Conditions ◽  
Soil Water Stress ◽  
Forest Meteorology ◽  
Weather And Climate

Current land surface schemes in weather and climate models make use of the so-called coupled photosynthesis–stomatal conductance (A–gs) models of plant function to determine the surface fluxes that govern the terrestrial energy, water and carbon budgets. Plant physiology is controlled by many environmental factors, and a number of complex feedbacks are involved, but soil moisture control on root water uptake is primary, particularly in sub-tropical to temperate ecosystems. Land surface models represent plant water stress in different ways, but most implement a water stress factor, β, which ranges linearly (more recently also curvilinearly) between β = 1 for unstressed vegetation and β = 0 at the wilting point, expressed in terms of volumetric water content (θ).  β is most commonly used to either limit A or gs, and hence carbon and water fluxes, and a pertinent research question is whether these treatments are in fact interchangeable. Following Egea et al. (Agricultural and Forest Meteorology, 2011, 151 (10), 1,370–1,384) and Verhoef et al. (Agricultural and Forest Meteorology, 2014, 191, 22–32), we have implemented new β treatments, reflecting higher levels of biophysical complexity in a state-of-the-art LSM, Joint UK Land Environment Simulator, by allowing root zone soil moisture to limit plant function non-linearly and via individual routes (carbon assimilation, stomatal conductance, or mesophyll conductance) as well as any (non-linear) combinations thereof. The treatment of β does matter to the prediction of water and carbon fluxes: this study demonstrates that it represents a key structural uncertainty in contemporary LSMs, in terms of predictions of gross primary productivity, energy fluxes and soil moisture evolution, both in terms of climate means and response to a number of European droughts, including the 2003 heat wave. Treatments allowing ß to act on vegetation fluxes via stomatal and mesophyll routes are able to simulate the spatiotemporal variability in water use efficiency with higher fidelity during the growing season; they also support a broader range of ecosystem responses, e.g., those observed in regions that are radiation limited or water limited. We conclude that current practice in weather and climate modelling is inconsistent, as well as too simplistic, failing to credibly simulate vegetation response to soil water stress across the typical range of variability that is encountered for current European weather and climate conditions, including extremes of land surface temperature and soil moisture drought. A generalized approach performs better in current climate conditions and promises to be, based on responses to recently observed extremes, more trustworthy for predicting the impacts of climate change.

Effect of Water Stress on Photosynthetic Parameters of Soybean (Glycine max) and Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
1987 ◽  
Vol 35 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Philip H. Munger ◽  
James M. Chandler ◽  
J. Tom Cothren
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Abutilon Theophrasti ◽  
Leaf Water ◽  
Photosynthetic Parameters

Greenhouse experiments were conducted to elucidate the effects of water stress on photosynthetic parameters of soybean [Glycine max(L.) Merr. ‘Hutton′] and velvetleaf (Abutilon theophrastiMedik. # ABUTH). Stomatal conductance of both species responded curvilinearly to reductions in leaf water potential. At leaf water potentials less negative than −2.5 MPa, stomatal conductance, net photosynthetic rate, and transpiration rate were greater in velvetleaf than in soybean. Soybean photosynthetic rate was linearly related to stomatal conductance. Velvetleaf photosynthetic rate increased linearly with stomatal conductances up to 1.5 cm s–1; however, no increase in photosynthetic rate was observed at stomatal conductances greater than 1.5 cm s–1, indicating nonstomatal limitations to photosynthesis. As water stress intensified, stomatal conductance, photosynthetic rate, and transpiration of velvetleaf declined more rapidly than in soybean.

Evidence for nonstomatal inhibition of net photosynthesis in rapidly dehydrated shoots of Populus

1986 ◽  
Vol 16 (6) ◽  
pp. 1371-1375 ◽  
Author(s):  
G. Scarascia-Mugnozza ◽  
T. M. Hinckley ◽  
R. F. Stettler
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Net Photosynthesis ◽  
Volume Shrinkage ◽  
Sharp Reduction ◽  
Stomatal Behaviour ◽  
Net Assimilation ◽  
Protoplast Volume

Results are presented on the decline of net photosynthesis during the application of rapid water stress to excised shoots of different Populus L. clones. Six clones were selected from the species Populustrichocarpa Torr. & Gray, Populusdeltoides Bartr., and from the hybrid Populustrichocarpa × Populusdeltoides, taking into account the differences in stomatal behaviour between and within these species. The two most productive P. trichocarpa clones and the hybrid clone, characterized by a reduced ability to close stomata during leaf desiccation, showed, nevertheless, a sharp reduction of net photosynthesis at water potentials lower than −1.5 MPa. In contrast, the inhibition of net assimilation in the P. deltoides clone, caused by water stress, was accompanied by a reduction in stomatal conductance. In all studied clones the decrease in net photosynthetic rate followed closely the point of turgor loss of the leaves, indicating a possible relationship between nonstomatal inhibition of photosynthesis and protoplast volume shrinkage.

Sign in / Sign up

Export Citation Format

Share Document