Water transport from stem to stomata: the coordination of hydraulic and gas exchange traits across 33 subtropical woody species

2019 ◽  
Vol 39 (10) ◽  
pp. 1665-1674 ◽  
Author(s):  
Xiaorong Liu ◽  
Hui Liu ◽  
Sean M Gleason ◽  
Guillermo Goldstein ◽  
Shidan Zhu ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Transport ◽  
Explanatory Power ◽  
Woody Species ◽  
Hydraulic Conductance ◽  
Co2 Assimilation ◽  
Leaf Hydraulic Conductance ◽  
Net Co2 Assimilation ◽  
Leaf Tissues

Abstract Coordination between sapwood-specific hydraulic conductivity (Ks) and stomatal conductance (gs) has been identified in previous studies; however, coordination between leaf hydraulic conductance (Kleaf) and gs, as well as between Kleaf and Ks is not always consistent. This suggests that there is a need to improve our understanding of the coordination among hydraulic and gas exchange traits. In this study, hydraulic traits (e.g., Ks and Kleaf) and gas exchange traits, including gs, transpiration (E) and net CO2 assimilation (Aarea), were measured across 33 co-occurring subtropical woody species. Kleaf was divided into two components: leaf hydraulic conductance inside the xylem (Kleaf-x) and outside the xylem (Kleaf-ox). We found that both Kleaf-x and Kleaf-ox were coordinated with gs and E, but the correlations between Kleaf-ox and gs (or E) were substantially weaker, and that Ks was coordinated with Kleaf-x, but not with Kleaf-ox. In addition, we found that Ks, Kleaf-x and Kleaf-ox together explained 63% of the variation in gs and 42% of the variation in Aarea across species, with Ks contributing the largest proportion of explanatory power, whereas Kleaf-ox contributed the least explanatory power. Our results demonstrate that the coordination between leaf water transport and gas exchange, as well as the hydraulic linkage between leaf and stem, were weakened by Kleaf-ox. This highlights the possibility that water transport efficiencies of stem and leaf xylem, rather than that of leaf tissues outside the xylem, are important determinants of stomatal conductance and photosynthetic capacity across species.

scholarly journals 476 Reducing Midday Irradiance Increases Net CO2 Assimilation in Citrus Leaves

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 476B-476
Author(s):  
John L. Jifon ◽  
Jim Syvertsen
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Vapor Pressure ◽  
Beneficial Effect ◽  
Leaf Gas Exchange ◽  
Co2 Assimilation ◽  
High Irradiance ◽  
Air Temperatures ◽  
Net Co2 Assimilation ◽  
Citrus Leaves

Maximum CO2 assimilation rates (ACO2) in citrus are not realized in environments with high irradiance, high temperatures, and high leaf-to-air vapor pressure differences (D). We hypothesized that moderate shading would reduce leaf temperature and D, thereby increasing stomatal conductance (gs) and ACO2. A 61% reduction in irradiance under aluminum net shade screens reduced midday leaf temperatures by 8 °C and D by 62%. This effect was prominent on clear days when average midday air temperature and vapor pressure deficits exceeded 30 °C and 3 kPa. ACO2 and gs increased 42% and 104%, respectively, in response to shading. Although shaded leaves had higher gs, their transpiration rates were only 7% higher and not significantly different from sunlit leaves. Leaf water use efficiency (WUE) was significantly improved in shaded leaves (39%) compared to sunlit leaves due to the increase in ACO2. Early in the morning and late afternoon when irradiance and air temperatures were low, shading had no beneficial effect on ACO2 or other gas exchange characteristics. On cloudy days or when the maximum daytime temperature and atmospheric vapor pressure deficits were less than 30 °C and 2 kPa, respectively, shading had little effect on leaf gas exchange properties. The results are consistent with the hypothesis that the beneficial effect of radiation load reduction on ACO2 is related to improved stomatal conductance in response to lowered D.

scholarly journals Ethylene enhances root water transport and aquaporin expression in trembling aspen (Populus tremuloides) exposed to root hypoxia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiangfeng Tan ◽  
Mengmeng Liu ◽  
Ning Du ◽  
Janusz J. Zwiazek
Keyword(s):  
Gas Exchange ◽  
Water Transport ◽  
Populus Tremuloides ◽  
Leaf Gas Exchange ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Trembling Aspen ◽  
Expression Levels ◽  
Root Hypoxia ◽  
Exogenous Ethylene

Abstract Background Root hypoxia has detrimental effects on physiological processes and growth in most plants. The effects of hypoxia can be partly alleviated by ethylene. However, the tolerance mechanisms contributing to the ethylene-mediated hypoxia tolerance in plants remain poorly understood. Results In this study, we examined the effects of root hypoxia and exogenous ethylene treatments on leaf gas exchange, root hydraulic conductance, and the expression levels of several aquaporins of the plasma membrane intrinsic protein group (PIP) in trembling aspen (Populus tremuloides) seedlings. Ethylene enhanced net photosynthetic rates, transpiration rates, and root hydraulic conductance in hypoxic plants. Of the two subgroups of PIPs (PIP1 and PIP2), the protein abundance of PIP2s and the transcript abundance of PIP2;4 and PIP2;5 were higher in ethylene-treated trembling aspen roots compared with non-treated roots under hypoxia. The increases in the expression levels of these aquaporins could potentially facilitate root water transport. The enhanced root water transport by ethylene was likely responsible for the increase in leaf gas exchange of the hypoxic plants. Conclusions Exogenous ethylene enhanced root water transport and the expression levels of PIP2;4 and PIP2;5 in hypoxic roots of trembling aspen. The results suggest that ethylene facilitates the aquaporin-mediated water transport in plants exposed to root hypoxia.

scholarly journals Salt tolerance and regulation of gas exchange and hormonal homeostasis by auxin-priming in wheat

2013 ◽  
Vol 48 (9) ◽  
pp. 1210-1219 ◽  
Author(s):  
Muhammad Iqbal ◽  
Muhammad Ashraf
Keyword(s):  
Abscisic Acid ◽  
Gas Exchange ◽  
Acid Concentration ◽  
Spring Wheat ◽  
Indoleacetic Acid ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation Rate ◽  
Net Co2 Assimilation

The objective of this work was to assess the regulatory effects of auxin-priming on gas exchange and hormonal homeostasis in spring wheat subjected to saline conditions. Seeds of MH-97 (salt-intolerant) and Inqlab-91 (salt-tolerant) cultivars were subjected to 11 priming treatments (three hormones x three concentrations + two controls) and evaluated under saline (15 dS m-1) and nonsaline (2.84 dS m-1) conditions. The priming treatments consisted of: 5.71, 8.56, and 11.42 × 10-4 mol L-1 indoleacetic acid; 4.92, 7.38, and 9.84 × 10-4 mol L-1 indolebutyric acid; 4.89, 7.34, and 9.79 × 10-4 mol L-1 tryptophan; and a control with hydroprimed seeds. A negative control with nonprimed seeds was also evaluated. All priming agents diminished the effects of salinity on endogenous abscisic acid concentration in the salt-intolerant cultivar. Grain yield was positively correlated with net CO2 assimilation rate and endogenous indoleacetic acid concentration, and it was negatively correlated with abscisic acid and free polyamine concentrations. In general, the priming treatment with tryptophan at 4.89 × 10-4 mol L-1 was the most effective in minimizing yield losses and reductions in net CO2 assimilation rate, under salt stress conditions. Hormonal homeostasis increases net CO2 assimilation rate and confers tolerance to salinity on spring wheat.

scholarly journals Growth and grain yield of eight maize hybrids is aligned with water transport, stomatal conductance, and photosynthesis in a semi-arid irrigated system

2021 ◽  
Author(s):  
Sean M Gleason ◽  
Lauren Nalezny ◽  
Cameron Hunter ◽  
Robert Bensen ◽  
Satya Chintamanani ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Grain Yield ◽  
Water Transport ◽  
Co2 Assimilation ◽  
Specific Conductance ◽  
Soil Conditions ◽  
Transport Pathway ◽  
Crop Species ◽  
Leaf Level ◽  
Improved Performance

There is increasing interest in understanding how trait networks can be manipulated to improve the performance of crop species. Working towards this goal, we have identified key traits linking the acquisition of water, the transport of water to the sites of evaporation and photosynthesis, stomatal conductance, and growth across eight maize hybrid lines grown under well-watered and water-limiting conditions in Northern Colorado. Under well-watered conditions, well-performing hybrids exhibited high leaf-specific conductance, low operating water potentials, high rates of midday stomatal conductance, high rates of net CO2 assimilation, greater leaf osmotic adjustment, and higher end-of-season growth and grain yield. This trait network was similar under water-limited conditions with the notable exception that linkages between water transport, midday stomatal conductance, and growth were even stronger than under fully-watered conditions. The results of this experiment suggest that similar trait networks might confer improved performance under contrasting climate and soil conditions, and that efforts to improve the performance of crop species could possibly benefit by considering the water transport pathway within leaves, as well as within the whole-xylem, in addition to root-level and leaf-level traits.

Shade tree species affect gas exchange and hydraulic conductivity of cacao cultivars in an agroforestry system

2020 ◽  
Author(s):  
Eleinis Ávila-Lovera ◽  
Héctor Blanco ◽  
Olga Móvil ◽  
Louis S Santiago ◽  
Wilmer Tezara
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Co2 Assimilation ◽  
Agroforestry System ◽  
Timber Species ◽  
Positive Contribution ◽  
Assimilation Rate ◽  
Co2 Assimilation Rate ◽  
Carbon Economy

Abstract Shade tolerance is a widespread strategy of rainforest understory plants. Many understory species have green young stems that may assimilate CO2 and contribute to whole-plant carbon balance. Cacao commonly grows in the shaded understory and recent emphasis has been placed on diversifying the types of trees used to shade cacao plants to achieve additional ecosystem services. We studied three agricultural cacao cultivars growing in the shade of four timber species (Cedrela odorata L., Cordia thaisiana Agostini, Swietenia macrophylla King and Tabebuia rosea (Bertol) A.D.C.) in an agroforestry system to (i) evaluate the timber species for their effect on the physiological performance of three cacao cultivars; (ii) assess the role of green stems on the carbon economy of cacao; and (iii) examine coordination between stem hydraulic conductivity and stem photosynthesis in cacao. Green young stem photosynthetic CO2 assimilation rate was positive and double leaf CO2 assimilation rate, indicating a positive contribution of green stems to the carbon economy of cacao; however, green stem area is smaller than leaf area and its relative contribution is low. Timber species showed a significant effect on leaf gas exchange traits and on stomatal conductance of cacao, and stem water-use efficiency varied among cultivars. There were no significant differences in leaf-specific hydraulic conductivity among cacao cultivars, but sapwood-specific hydraulic conductivity varied significantly among cultivars and there was an interactive effect of cacao cultivar × timber species. Hydraulic efficiency was coordinated with stem-stomatal conductance, but not with leaf-stomatal conductance or any measure of photosynthesis. We conclude that different shade regimes determined by timber species and the interaction with cacao cultivar had an important effect on most of the physiological traits and growth variables of three cacao cultivars growing in an agroforestry system. Results suggested that C. odorata is the best timber species to provide partial shade for cacao cultivars in the Barlovento region in Venezuela, regardless of cultivar origin.

scholarly journals Gas exchange recovery following natural drought is rapid unless limited by loss of leaf hydraulic conductance: evidence from an evergreen woodland

2017 ◽  
Vol 215 (4) ◽  
pp. 1399-1412 ◽  
Author(s):  
Robert P. Skelton ◽  
Timothy J. Brodribb ◽  
Scott A. M. McAdam ◽  
Patrick J. Mitchell
Keyword(s):  
Gas Exchange ◽  
Hydraulic Conductance ◽  
Leaf Hydraulic Conductance

scholarly journals A mutation that eliminates bundle sheath extensions reduces leaf hydraulic conductance, stomatal conductance and assimilation rates in tomato (Solanum lycopersicum)

2014 ◽  
Vol 205 (2) ◽  
pp. 618-626 ◽  
Author(s):  
Agustin Zsögön ◽  
Ana Clarissa Alves Negrini ◽  
Lázaro Eustáquio Pereira Peres ◽  
Hoa Thi Nguyen ◽  
Marilyn C. Ball
Keyword(s):  
Stomatal Conductance ◽  
Solanum Lycopersicum ◽  
Hydraulic Conductance ◽  
Bundle Sheath ◽  
Leaf Hydraulic Conductance

scholarly journals Leaf hydraulic safety margin and safety–efficiency trade-off across angiosperm woody species

2020 ◽  
Vol 16 (11) ◽  
pp. 20200456
Author(s):  
Chao-Long Yan ◽  
Ming-Yuan Ni ◽  
Kun-Fang Cao ◽  
Shi-Dan Zhu
Keyword(s):  
Water Potential ◽  
Global Analysis ◽  
Safety Margin ◽  
Woody Species ◽  
Hydraulic Conductance ◽  
Plant Distribution ◽  
Mean Annual Precipitation ◽  
Leaf Hydraulic Conductance ◽  
Hydraulic Safety ◽  
Hydraulic Safety Margin

Leaf hydraulic conductance and the vulnerability to water deficits have profound effects on plant distribution and mortality. In this study, we compiled a leaf hydraulic trait dataset with 311 species-at-site combinations from biomes worldwide. These traits included maximum leaf hydraulic conductance ( K leaf ), water potential at 50% loss of K leaf (P50 leaf ), and minimum leaf water potential ( Ψ min ). Leaf hydraulic safety margin (HSM leaf ) was calculated as the difference between Ψ min and P50 leaf . Our results indicated that 70% of the studied species had a narrow HSM leaf (less than 1 MPa), which was consistent with the global pattern of stem hydraulic safety margin. There was a positive relationship between HSM leaf and aridity index (the ratio of mean annual precipitation to potential evapotranspiration), as species from humid sites tended to have larger HSM leaf . We found a significant relationship between K leaf and P50 leaf across global angiosperm woody species and within each of the different plant groups. This global analysis of leaf hydraulic traits improves our understanding of plant hydraulic response to environmental change.

scholarly journals Influence of Surflan (Oryzalin) Concentrations in Irrigation Water on Growth and Physiological Processes of Gardenia jasminoides radicans and Pennisetum rupelli

1997 ◽  
Vol 15 (4) ◽  
pp. 169-172
Author(s):  
Rajgopal Bhandary ◽  
Ted Whitwell ◽  
Jeanne Briggs ◽  
R. Thomas Fernandez
Keyword(s):  
Stomatal Conductance ◽  
Irrigation Water ◽  
Treatment Initiation ◽  
Co2 Assimilation ◽  
Ethylene Synthesis ◽  
Sensitive Species ◽  
Ethylene Evolution ◽  
Gardenia Jasminoides ◽  
Physiological Processes ◽  
Net Co2 Assimilation

Abstract This study investigated the effect of oryzalin concentrations on growth, CO2 assimilation, stomatal conductance, transpiration and ethylene synthesis in dwarf gardenia and fountain grass (tolerant and sensitive species). The plant species were subjected to irrigation water containing 10 μg/liter, 100 μg/liter and 1000 μg/liter oryzalin. CO2 assimilation, stomatal conductance and transpiration were measured 2 and 4 weeks after treatment initiation, and ethylene evolution was determined at the end of the study. Oryzalin did not affect net CO2 assimilation, stomatal conductance, transpiration or ethylene evolution for dwarf gardenia or fountain grass. Dwarf gardenia shoot and root weights were not affected by oryzalin, but shoot and root weights of fountain grass were reduced by the highest concentration.

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