scholarly journals Intrinsic water use efficiency depends on stomatal aperture rather than stomatal density in C3 and C4 grasses grown at glacial CO2 and low light

2021 ◽  
Author(s):  
Walter K Israel ◽  
Alex Watson-Lazowski ◽  
Zhong-Hua Chen ◽  
Oula Ghannoum
Keyword(s):  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Stomatal Aperture ◽  
C4 Grasses ◽  
Low Light ◽  
Influx Rate ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

We investigated how stomatal morphology and physiology control intrinsic leaf water use efficiency (iWUE) in grasses. Two C3 and six C4 grasses were grown at ambient (400 μl L-1) or glacial CO2 (180 μl L-1) and high (1000 μmol m-2 s-1) or low light intensity (200 μmol m-2 s-1). C4 grasses tended to have higher iWUE and CO2 assimilation rates, and lower stomatal conductance (gs), operational stomatal aperture (aop) and guard cell K+ influx rate relative to C3 grasses, while stomatal size (SS) and stomatal density (SD) did not vary according to the photosynthetic type. Overall, iWUE and gs depended most on aop and density of open stomata. In turn, aop correlated with K+ influx, stomatal opening speed on transition to high light and SS. Species with higher SD had smaller and faster-opening stomata. Although C4 grasses operated with lower gs and aop at ambient CO2, they showed a greater potential to open stomata relative to maximal stomatal conductance (gmax), indicating heightened stomatal sensitivity and control. We uncover novel links between aop, gs, iWUE and K+ influx amongst grasses and differential K+ influx responses of C4 guard cells to low light, revealing molecular targets for breeding crops with high iWUE.

scholarly journals Coordination of stomata and vein patterns with leaf width underpins water use efficiency in a C4 crop

2021 ◽  
Author(s):  
Ling Pan ◽  
Barbara George-Jaeggli ◽  
Andrew Borrell ◽  
David Jordan ◽  
Fiona Koller ◽  
...  
Keyword(s):  
Energy Balance ◽  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Leaf Gas Exchange ◽  
Crop Productivity ◽  
Stomatal Aperture ◽  
Leaf Width ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Despite its importance for crop productivity in drought-affected environments, the underlying mechanisms of variation in intrinsic water use efficiency (iWUE) are not well understood, especially in C4 plants. Recently, Cano et al. (2019) discovered that leaf width (LW) correlated negatively with iWUE and positively with stomatal conductance for water vapour (gsw) across several C4 grasses. Here, we analysed these relationships within 48 field-grown genotypes that cover a broad range of variation in LW in Sorghum bicolor, a well-adapted C4 crop to xeric and hot conditions, by measuring and modelling leaf gas exchange and leaf energy balance three times a day, using anatomical traits as potential drivers for iWUE. LW correlated negatively with iWUE and stomatal density, but positively with gsw, interveinal distance of longitudinal veins (IVDL) and the percentage of stomatal aperture relative to maximum. Energy balance modelling showed that wider leaves opened the stomata more to generate a more negative leaf-to-air temperature difference especially at midday, when air temperatures exceeded 40ºC. These results highlight the important role that LW plays in shaping iWUE through modification of vein and stomatal traits and by regulating stomatal aperture. Therefore, LW could be used as a predictor for higher iWUE among sorghum genotypes.

scholarly journals Apparent Tolerance of Low Water Availability in Temperate Asian Bamboos1

2018 ◽  
Vol 36 (1) ◽  
pp. 7-13
Author(s):  
Melissa C. Smith ◽  
Richard N. Mack
Keyword(s):  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
Water Use ◽  
North American ◽  
Water Availability ◽  
Irrigation Treatment ◽  
Bamboo Species ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Pleioblastus Chino

Abstract Suitable plant water dynamics and the ability to withstand periods of low moisture input facilitate plant establishment in seasonally arid regions. Temperate bamboos are a major constituent of mixed evergreen and deciduous forests throughout temperate East Asia but play only an incidental role in North American forests and are altogether absent in the Pacific Northwest forest. Many bamboo species are classified as mesic or riparian, but none are considered drought tolerant. To assess their ability to withstand low water, we subjected five Asian temperate and one North American temperate bamboo species to three irrigation treatments: 100%, 50%, and 10% replacement of water lost through evapotranspiration. Plants were irrigated every four days over a 31-day period. Plant response to treatments was measured with stomatal conductance, leaf xylem water potentials, and intrinsic water use efficiency (iWUE). Pleioblastus distichus and Pseudosasa japonica showed significant reductions in conductance between high and low irrigation treatments. Sasa palmata had significantly lower stomatal conductance in all treatments. Pleioblastus chino displayed significantly higher iWUE in the mid irrigation treatment and Arunindaria gigantea displayed significantly lower iWUE than P. chino and S. palmata in the low irrigation treatment. The Asian bamboo species examined here tolerate low water availability and readily acclimate to different soil moisture conditions. Index words: Temperate bamboos, irrigation response, stomatal conductance, intrinsic water use efficiency. Species used in this study: Giant Cane [Arundinaria gigantea (Walt.) Muhl.]; Pleioblastus chino (Franchet & Savatier) Makino; Pleioblastus distichus (Mitford) Nakai; Pseudosasa japonica (Makino); Sasa palmata (Bean) Nakai.

scholarly journals 20th-century changes in carbon isotopes and water-use efficiency: Tree-ring based evaluation of the CLM4.5 and LPX-Bern models

2016 ◽  
Author(s):  
Kathrin M. Keller ◽  
Sebastian Lienert ◽  
Anil Bozbiyik ◽  
Thomas F. Stocker ◽  
Olga V. Churakova ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
20Th Century ◽  
Water Use ◽  
Tree Ring ◽  
Dynamic Global Vegetation Model ◽  
Isotopic Discrimination ◽  
Tree Ring Data ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Abstract. Measurements of the stable carbon isotope ratio (δ13C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO2 and climate, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO2 partial pressure in the intercellular cavities and the atmosphere (ci / ca) and of the ratio of assimilation to stomatal conductance, termed intrinsic water-use efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the LPX-Bern dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ13C measurements on leaves, though modeled 13C discrimination by C3 trees is smaller in arid regions than measured. A compilation of seventy-six tree-ring records, mainly from Europe, boreal Asia, and western North America, suggest on average small 20th-century changes in isotopic discrimination and an increase in iWUE of about 27 % since 1900. LPX-Bern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO2. The results suggest that the down-regulation of ci / ca and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or there may be more fundamental problems associated with the prescribed relationship between conductance and assimilation.

Incontinence in aging leaves: deteriorating water relations with leaf age in Agastachys odorata (Proteaceae), a shrub with very long-lived leaves

2007 ◽  
Vol 34 (10) ◽  
pp. 918 ◽  
Author(s):  
Gregory J. Jordan ◽  
Timothy J. Brodribb
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Leaf Age ◽  
Carbon Assimilation ◽  
Leaf Damage ◽  
Evergreen Species ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Cuticle Thickness

This paper examines physiological characteristics of the leaves of Agastachys odorata R.Br., a wet-climate sclerophyllous shrub with very long-lived leaves. It addresses the hypothesis that cuticles become leakier to water vapour as leaves age. Astomatous cuticular conductance, whole-leaf minimum epidermal conductance, leaf damage and accumulation of epiphylls all increased several-fold with leaf age from first year growth to 10 years of age. Maximum carbon assimilation peaked 1 year after full leaf expansion, then declined. Intrinsic water use efficiency was highest in mid-aged leaves and declined markedly in the oldest leaves. Stomatal density, stomatal size and cuticle thickness did not vary significantly among ages. The older leaves were less effective at controlling water loss, resulting in decreases in water use efficiency. A differential increase in the conductance of the stomatal surface of the leaves relative to astomatous surface suggested that stomatal leakiness was significant in leaves over five years old. Although data for other species is ambiguous, the deterioration in A. odorata appears to be consistent with changes in the oldest leaves of other species. Thus, decreasing ability to use water efficiently appears to be a consequence of accumulated damage and may contribute to the need for leaf senescence in evergreen species with little self shading.

Plant water use efficiency of 17 Australian NAD-ME and NADP-ME C4 grasses at ambient and elevated CO2 partial pressure

2001 ◽  
Vol 28 (12) ◽  
pp. 1207 ◽  
Author(s):  
Oula Ghannoum ◽  
Susanne von Caemmerer ◽  
Jann P. Conroy
Keyword(s):  
Stomatal Conductance ◽  
Partial Pressure ◽  
Water Use Efficiency ◽  
Water Use ◽  
Elevated Pco2 ◽  
Plant Water ◽  
C4 Grasses ◽  
Co2 Partial Pressure ◽  
Plant Water Use ◽  
Use Efficiency

This study investigates the response to elevated CO2 partial pressure (pCO2) of C4grasses belonging to different biochemical subtypes (NAD–ME and NADP–ME), and taxonomic groups (main Chloroid assemblage, Paniceae and Andropogoneae). Seventeen C4 grasses were grown under well-watered conditions in two glasshouses maintained at an average dailyppCO2 of 42 (ambient) or 68 (elevated) Pa. Elevated pCO2 significantly increased plant water-use efficiency (WUE; dry matter gain per unit water transpired) in 12 out of the 17 C4 grasses, by an average of 33%. In contrast, only five species showed a significant growth stimulation. When all species are considered, the average plant dry mass enhancement at elevated pCO2 was 26%. There were no significant subtype (or taxa) × pCO2 interactions on either WUE or biomass accumulation. When leaf gas exchange was compared at growth pCO2 but similar light and temperature, high pCO2-grown plants had similar CO2 assimilation rates (A) but a 40% lower stomatal conductance than their low pCO2-grown counterparts. There were no signs of either photosynthetic or stomatal acclimation in any of the measured species. We conclude that elevated pCO2 improved WUE primarily by reducing stomatal conductance.

scholarly journals Diurnal stomatal apertures and density ratios affect whole-canopy stomatal conductance, water-use efficiency and yield

2022 ◽  
Author(s):  
SANBON GOSA ◽  
Bogale Abebe Gebeyo ◽  
Ravitejas Patil ◽  
Ramon Mencia ◽  
Menachem Moshelion
Keyword(s):  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Density Ratio ◽  
Physiological Traits ◽  
Stomatal Development ◽  
Whole Plant ◽  
Use Efficiency ◽  
Density Ratios

Key physiological traits of plants, such as transpiration and stomatal conductance, are usually studied under steady-state conditions or modeled using only a few measured data points. Those measurements do not reflect the dynamic behavior of the plant in response to field conditions. To overcome this bottleneck, we used a gravimetric functional phenotyping platform and a reverse-phenotyping method to examine the dynamic whole-plant water regulation responses of tomato introgression lines and compared those responses with several years of yield performance in commercial fields. Ideotype lines had highly plastic stomatal conductance and high abaxial to adaxial stomatal density ratios and the size of their stomatal apertures peaked early in the day under water-deficit conditions. These traits resulted in dynamic daily water-use efficiency, which allowed for the rapid recovery of transpiration when irrigation was resumed after a period of imposed drought. We found that stomatal density, the abaxial to adaxial stomatal density ratio and the time of maximum stomatal apertures are crucial for plant adaptation and productivity under drought stress conditions. Abaxial stomatal density was also found to be strongly correlated with the expression of the stomatal-development genes SPCH and ZEP. This study demonstrates how a reverse functional phenotyping approach based on field yield data, continuous and simultaneous whole plant waterbalance measurements and anatomical examination of individual leaves can help us to understand and identify dynamic and complex yield-related physiological traits.

The effects of sodium sulphate and sodium chloride on growth, morphology, photosynthesis, and water use efficiency of Chenopodium rubrum

1990 ◽  
Vol 68 (5) ◽  
pp. 999-1006 ◽  
Author(s):  
Patricia Warne ◽  
R. D. Guy ◽  
Lorna Rollins ◽  
D. M. Reid
Keyword(s):  
Sodium Chloride ◽  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Stable Carbon Isotope ◽  
Dry Weight ◽  
Sodium Sulphate ◽  
Chenopodium Rubrum ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

The effects of sodium sulphate and sodium chloride salinity on the anatomy, water relations, and photosynthesis of Chenopodium rubrum L. were compared. Low concentrations of either salt stimulated growth, but higher concentrations resulted in large decreases in dry weight and leaf area. Leaf succulence and the number of layers of palisade cells were increased, but these effects were more pronounced with NaCl than with Na2SO4. Stomatal density was reduced at low to moderate salinities, but then increased again at high salinity. Stomatal size was reduced at all salinities. Increasing salinity had no great effect on photosynthetic rates except with older plants grown at the highest level of Na2SO4. Stomatal conductance decreased at all salinities. This reduced transpiration and led to increased intrinsic water use efficiency. Total tissue stable carbon isotope ratios also indicated that water use efficiency was improved. Chenopodium rubrum adjusted osmotically by accumulating electrolytes from the nutrient solution and by synthesizing glycinebetaine. Plants in NaCl limited osmotic adjustment more than those growing in Na2SO4. Despite this, Na2SO4 was more damaging than NaCl and caused earlier leaf senescence at high concentrations.

scholarly journals 20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models

2017 ◽  
Vol 14 (10) ◽  
pp. 2641-2673 ◽  
Author(s):  
Kathrin M. Keller ◽  
Sebastian Lienert ◽  
Anil Bozbiyik ◽  
Thomas F. Stocker ◽  
Olga V. Churakova (Sidorova) ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Use Efficiency ◽  
20Th Century ◽  
Water Use ◽  
Tree Ring ◽  
Dynamic Global Vegetation Model ◽  
Isotopic Discrimination ◽  
Tree Ring Data ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Abstract. Measurements of the stable carbon isotope ratio (δ13C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO2 partial pressure in the intercellular cavities and the atmosphere (ci∕ca) and of the ratio of assimilation to stomatal conductance, termed intrinsic water-use efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the Land Surface Processes and Exchanges (LPX-Bern) dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ13C measurements on leaves, though modeled 13C discrimination by C3 trees is smaller in arid regions than measured. A compilation of 76 tree-ring records, mainly from Europe, boreal Asia, and western North America, suggests on average small 20th century changes in isotopic discrimination and in ci∕ca and an increase in iWUE of about 27 % since 1900. LPX-Bern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss by transpiration. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as that revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO2. The results suggest that the downregulation of ci∕ca and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or that there may be problems associated with the implementation of conductance, assimilation, and related adjustment processes on long-term environmental changes.

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