Leaf mass area determines water use efficiency through its influence on carbon gain in rice mutants

2020 ◽  
Vol 169 (2) ◽  
pp. 194-213 ◽  
Author(s):  
Sowmya Handenahally Reddy ◽  
Rajesh Kumar Singhal ◽  
Maria Vera Jesus DaCosta ◽  
Sumanth Kumar Kambalimath ◽  
Mavinahalli P Rajanna ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Carbon Gain ◽  
Leaf Mass ◽  
Leaf Mass Area ◽  
Use Efficiency

Water Use Efficiency as a Constraint and Target for Improving the Resilience and Productivity of C3and C4Crops

2019 ◽  
Vol 70 (1) ◽  
pp. 781-808 ◽  
Author(s):  
Andrew D.B. Leakey ◽  
John N. Ferguson ◽  
Charles P. Pignon ◽  
Alex Wu ◽  
Zhenong Jin ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Crop Production ◽  
Crop Improvement ◽  
Canopy Structure ◽  
Complex Trait ◽  
Carbon Gain ◽  
Crop Development ◽  
Component Traits ◽  
Use Efficiency

The ratio of plant carbon gain to water use, known as water use efficiency (WUE), has long been recognized as a key constraint on crop production and an important target for crop improvement. WUE is a physiologically and genetically complex trait that can be defined at a range of scales. Many component traits directly influence WUE, including photosynthesis, stomatal and mesophyll conductances, and canopy structure. Interactions of carbon and water relations with diverse aspects of the environment and crop development also modulate WUE. As a consequence, enhancing WUE by breeding or biotechnology has proven challenging but not impossible. This review aims to synthesize new knowledge of WUE arising from advances in phenotyping, modeling, physiology, genetics, and molecular biology in the context of classical theoretical principles. In addition, we discuss how rising atmospheric CO2concentration has created and will continue to create opportunities for enhancing WUE by modifying the trade-off between photosynthesis and transpiration.

Diurnal Time Course of Leaf Gas Exchange Rates and Related Characters in Drought-Acclimated and Irrigated Trifolium Subterraneum.

1995 ◽  
Vol 22 (3) ◽  
pp. 461 ◽  
Author(s):  
J Vadell ◽  
C Cabot ◽  
H Medrano
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Water Use Efficiency ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Trifolium Subterraneum ◽  
Co2 Assimilation ◽  
Carbon Gain ◽  
Assimilation Rate ◽  
Use Efficiency

The effects of drought acclimation on the diurnal time courses of photosynthesis and related characters were studied in Trifolium subterraneum L. leaves during two consecutive late spring days. Leaf CO2 assimilation rate and transpiration rate followed irradiance variations in irrigated plants. Under drought, a bimodal pattern of leaf CO2 assimilation rate developed although stomatal conductance remained uniform and low. Instantaneous water-use efficiency was much higher in droughted plants during the early morning and late evening, while during the middle of the day it was close to the value of irrigated plants. Net carbon gain in plants under drought reached 40% of the carbon gain in irrigated plants with a significant saving of water (80%). Average data derived from midday values of leaf CO2 assimilation rates and instantaneous water-use efficiency did not provide good estimates of the daily carbon gain and water-use efficiency for droughted leaves. Coupled with the morphological changes as a result of acclimation to progressive drought, modifications of diurnal patterns of leaf gas exchange rates effectively contribute to a sustained carbon gain during drought. These modifications significantly improve water-use efficiency, mainly by enabling the plant to take advantage of morning and evening hours with high air humidity.

scholarly journals Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil–plant–atmosphere continuum

2014 ◽  
Vol 7 (5) ◽  
pp. 2193-2222 ◽  
Author(s):  
G. B. Bonan ◽  
M. Williams ◽  
R. A. Fisher ◽  
K. W. Oleson
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
Water Use ◽  
Functional Dependence ◽  
Moisture Stress ◽  
Leaf Water ◽  
Carbon Gain ◽  
Soil Moisture Stress ◽  
Use Efficiency

Abstract. The Ball–Berry stomatal conductance model is commonly used in earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must be empirically parameterized. We evaluated the Ball–Berry model used in the Community Land Model version 4.5 (CLM4.5) and an alternative stomatal conductance model that links leaf gas exchange, plant hydraulic constraints, and the soil–plant–atmosphere continuum (SPA). The SPA model simulates stomatal conductance numerically by (1) optimizing photosynthetic carbon gain per unit water loss while (2) constraining stomatal opening to prevent leaf water potential from dropping below a critical minimum. We evaluated two optimization algorithms: intrinsic water-use efficiency (ΔAn /Δgs, the marginal carbon gain of stomatal opening) and water-use efficiency (ΔAn /ΔEl, the marginal carbon gain of transpiration water loss). We implemented the stomatal models in a multi-layer plant canopy model to resolve profiles of gas exchange, leaf water potential, and plant hydraulics within the canopy, and evaluated the simulations using leaf analyses, eddy covariance fluxes at six forest sites, and parameter sensitivity analyses. The primary differences among stomatal models relate to soil moisture stress and vapor pressure deficit responses. Without soil moisture stress, the performance of the SPA stomatal model was comparable to or slightly better than the CLM Ball–Berry model in flux tower simulations, but was significantly better than the CLM Ball–Berry model when there was soil moisture stress. Functional dependence of gs on soil moisture emerged from water flow along the soil-to-leaf pathway rather than being imposed a priori, as in the CLM Ball–Berry model. Similar functional dependence of gs on Ds emerged from the ΔAn/ΔEl optimization, but not the ΔAn /gs optimization. Two parameters (stomatal efficiency and root hydraulic conductivity) minimized errors with the SPA stomatal model. The critical stomatal efficiency for optimization (ι) gave results consistent with relationships between maximum An and gs seen in leaf trait data sets and is related to the slope (g1) of the Ball–Berry model. Root hydraulic conductivity (Rr*) was consistent with estimates from literature surveys. The two central concepts embodied in the SPA stomatal model, that plants account for both water-use efficiency and for hydraulic safety in regulating stomatal conductance, imply a notion of optimal plant strategies and provide testable model hypotheses, rather than empirical descriptions of plant behavior.

Plant Responses to Salinity Under Elevated Atmospheric Concentrations of CO2

1992 ◽  
Vol 40 (5) ◽  
pp. 515 ◽  
Author(s):  
MC Ball ◽  
R Munns
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Water Loss ◽  
Salt Flux ◽  
Carbon Gain ◽  
Salt Balance ◽  
Salt Uptake ◽  
Use Efficiency ◽  
Atmospheric Concentrations

This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of halophytic and non-halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be regulated to protect sensitive metabolic sites from salt toxicity. Salt-tolerant species exclude most of the salt from the transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concentrations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt storage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and the expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one of the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies coupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevated CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient and elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in both C3 and C2 non-halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust to environmental factors affecting the availability of water and ions at the roots (salinity) and those affecting carbon gain in relation to water loss at the leaves (atmospheric concentrations of water vapour and carbon dioxide).

The effect of drought on plant water use efficiency of nine NAD - ME and nine NADP - ME Australian C4 grasses

2002 ◽  
Vol 29 (11) ◽  
pp. 1337 ◽  
Author(s):  
Oula Ghannoum ◽  
Susanne von Caemmerer ◽  
Jann P. Conroy
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Malic Enzyme ◽  
Dry Matter ◽  
Mass Gain ◽  
Dry Mass ◽  
Carbon Gain ◽  
Dry Matter Accumulation ◽  
C4 Grasses ◽  
Use Efficiency

We investigated the response to drought of nine NAD–malic enzyme (NAD–ME) and nine NADP–malic enzyme (NADP–ME) C4 grasses. Species were grown from seeds in potted soil in a glasshouse. Seedlings were either watered regularly or exposed to two successive drying cycles of 8–10 d each, after which plants were harvested. Under well-watered conditions, average water use efficiency (WUE; dry mass gain per unit water transpired) was similar for NAD–ME and NADP–ME C4 grasses, and ranged between 6.0 and 8.7 g dry mass kg–1 H2O. Drought enhanced WUE of most species, but to a significantly greater extent in NAD–ME (1.20-fold) than NADP–ME (1.11-fold) grasses. Inhibition of dry matter accumulation (average of 12%) and shoot elongation under drought was similar among the C4 grasses. Leaf dry matter carbon (δ13C) and oxygen (δ18O) isotope compositions were significantly different between the two C4 subtypes. Leaf δ13C averaged –13.3 and –12.2, and leaf δ18O averaged 26.0 and 26.9 in well-watered NAD–ME and NADP–ME grasses, respectively. Drought significantly reduced leaf δ13C in most C4 grasses by an average 0.5. Leaf δ18O was not significantly affected by drought, indicating that leaf δ18O does not reflect drought-induced changes in leaf transpiration of C4 grasses. In the experiment reported here, NAD–ME grasses increased their WUE under drought to a greater extent than their NADP–ME counterparts. Increased WUE of the C4 grasses under drought was primarily related to control of water loss relative to carbon gain at the leaf, rather than the plant, level.

scholarly journals Remote Sensing of Water Use Efficiency and Terrestrial Drought Recovery across the Contiguous United States

2019 ◽  
Vol 11 (6) ◽  
pp. 731 ◽  
Author(s):  
Behzad Ahmadi ◽  
Ali Ahmadalipour ◽  
Glenn Tootle ◽  
Hamid Moradkhani
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Land Surface ◽  
Terrestrial Ecosystems ◽  
Agricultural Drought ◽  
Carbon Gain ◽  
Drought Severity ◽  
Drought Recovery ◽  
Ecosystem Water Use Efficiency ◽  
Use Efficiency

Ecosystem water-use efficiency (WUE) is defined as the ratio of carbon gain (i.e., gross primary productivity; GPP) to water consumption (i.e., evapotranspiration; ET). WUE is markedly influential on carbon and water cycles, both of which are fundamental for ecosystem state, climate and the environment. Drought can affect WUE, subsequently disturbing the composition and functionality of terrestrial ecosystems. In this study, the impacts of drought on WUE and its components (i.e., GPP and ET) are assessed across the Contiguous US (CONUS) at fine spatial and temporal resolutions. Soil moisture simulations from land surface modeling are utilized to detect and characterize agricultural drought episodes and remotely sensed GPP and ET are retrieved from the moderate resolution imaging spectroradiometer (MODIS). GPP, as the biome vitality indicator against drought stress, is employed to investigate drought recovery and the ecosystems’ required time to revert to pre-drought condition. Results show that drought recovery duration indicates a positive correlation with drought severity and duration, meaning that a protracted drought recovery is more likely to happen following severe droughts with prolonged duration. WUE is found to almost always increase in response to severe (or worse) drought episodes. Additionally, ET anomalies are negatively correlated with drought severity and ET is expected to decrease during severe (or worse) drought episodes. Lastly, the changes of WUE are decomposed in relation to its components and the cross-relation among the variables is revealed and a consistent changing pattern is detected.

scholarly journals Costs and benefits of photosynthetic stems in desert species from southern California

2019 ◽  
Vol 46 (2) ◽  
pp. 175 ◽  
Author(s):  
Eleinis Ávila-Lovera ◽  
Roxana Haro ◽  
Exequiel Ezcurra ◽  
Louis S. Santiago
Keyword(s):  
Isotopic Composition ◽  
Water Use Efficiency ◽  
Water Use ◽  
Water Loss ◽  
Water Status ◽  
Carbon Isotopic Composition ◽  
Carbon Gain ◽  
Costs And Benefits ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Woody plants with green photosynthetic stems are common in dry woodlands with the possible advantages of extra carbon gain, re-assimilation of CO2, and high water-use efficiency. However, their green stem tissue may also incur greater costs of water loss when stomata are closed. Our study focussed on evaluating the costs and benefits of having green stems in desert plants, addressing the water-use efficiency hypothesis. We measured water status, carbon and water exchange, and carbon, nitrogen and oxygen isotopic composition of 15 species in a desert wash scrub in Joshua Tree National Park, California, USA. We found that all woody species that have green stems relied on their green stems as the sole organ for carbon assimilation for most of the study period. Green stems had similar photosynthetic rate (Amax), stomatal conductance (gs) and intrinsic water-use efficiency (WUEi) to leaves of the same species. However, Amax, gs and cuticular conductance (gmin) were higher in green stems than in leaves of non-green stemmed species. Carbon isotopic composition (δ13C) was similar in both leaves and green stems, indicating no difference in integrated long-term WUE. Our results raise questions about the possible trade-off between carbon gain and water loss through the cuticle in green stems and how this may affect plant responses to current and future droughts.

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