Seasonal changes in tissue elasticity and water transport efficiency in three co-occurring Mediterranean shrubs under natural long-term CO2 enrichment

Seasonal changes in hydraulic properties and tissue elasticity were evaluated in Erica arborea L., Myrtus�communis L. and Juniperus communis L., three Mediterranean shrubs that differ in adaptations to drought. These parameters were analysed over 12 months under field conditions, by comparing plants grown in the proximity of a natural CO2 spring (about 700 μmol mol–1 atmospheric CO2 concentration, [CO2]) with plants in ambient conditions. Plants at the CO2-spring site have been growing for generations at elevated [CO2]. At both sites, stem hydraulic and structural properties followed the prevailing climatic constraints. However, these shrub species co-occurring in the same environment differed in their capacity to tolerate water deficits, in xylem efficiency, and in strategies for regulating water movement between plant compartments. Either an increase or a decrease in tissue elasticity was effective in promoting resistance to drought stress, depending on the species. Long-term elevated [CO2] influenced all the studied parameters. Species-dependent differences existed in hydraulic architecture between the CO2-spring plants and control plants of E. arborea and M. communis, while J. communis plants rarely showed differences between sites. Less distinct differences between sites were observed for wood structure. The three species showed somewhat lower tissue elasticity under elevated [CO2], in particular during stress periods. The effects of elevated [CO2] on stem hydraulic pathway and structure and shoot elastic properties persist in the long term, but differ in absolute values and sign among the studied species and with the seasonal course, and thus might alter competitive relations between these shrubs.

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Photosynthetic acclimation to elevated CO2 concentration in a sweet pepper (Capsicum annuum) crop under Mediterranean greenhouse conditions: influence of the nitrogen source and salinity

Functional Plant Biology ◽

10.1071/fp16362 ◽

2017 ◽

Vol 44 (6) ◽

pp. 573 ◽

Cited By ~ 4

Author(s):

Manuel E. Porras ◽

Pilar Lorenzo ◽

Evangelina Medrano ◽

María J. Sánchez-González ◽

Ginés Otálora-Alcón ◽

...

Keyword(s):

Capsicum Annuum ◽

Elevated Co2 ◽

Nutrient Solution ◽

Co2 Enrichment ◽

Co2 Concentration ◽

Sweet Pepper ◽

Elevated Co2 Concentration ◽

High Co2 ◽

High Co2 Concentration

In many plant species, long-term exposure to elevated CO2 concentration results in a reduction in photosynthetic capacity, known as acclimation. This process is mainly explained by a feedback inhibition mechanism. The supply of a fraction of the nitrogen (N) in the nutrient solution as NH4+ can play an important role in the maintenance of photosynthetic activity and could mitigate the acclimation process. The aims of the present work were to study the photosynthetic response of sweet pepper (Capsicum annuum L.) to CO2 enrichment in Mediterranean greenhouse conditions, throughout the crop growth cycle and to evaluate the supply of NH4+ in the nutrient solution as a strategy to enhance the long-term response to CO2 at different levels of salinity. The experiment was conducted in two identical greenhouses: one with CO2 enrichment according to the ventilation, maintaining a high concentration when the vents were closed and a near-atmospheric level when the vents were open and one without. Sweet pepper plants were grown in both greenhouses, being irrigated with two levels of water salinity and two N sources: (i) NO3– and (ii) NO3– plus NH4+. A reduction in the response of photosynthesis to high CO2 concentration was found in the enriched plants after 135 days of CO2 supply, with respect to the reference plants. The leaf photosynthesis rate measured at high CO2 concentration showed a closer relationship with the leaf N concentration than the non-structural carbohydrate concentration. The relative yield gain of the CO2-enriched plants progressively decreased after reaching a maximum value; this was probably associated with the photosynthetic acclimation process. This decrease was delayed by the use of NH4+ in the nutrient solution at low salinity. Knowledge of the crop phase when acclimation to high CO2 concentration occurs can be the basis for deciding when to impose an early cessation of CO2 application, as a strategy to improve the economic efficiency of CO2 supply in Mediterranean conditions.

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Canopy development and hydraulic function in Eucalyptus tereticornis grown in drought in CO2-enriched atmospheres

Functional Plant Biology ◽

10.1071/fp06338 ◽

2007 ◽

Vol 34 (12) ◽

pp. 1137 ◽

Cited By ~ 23

Author(s):

Brian J. Atwell ◽

Martin L. Henery ◽

Gordon S. Rogers ◽

Saman P. Seneweera ◽

Marie Treadwell ◽

...

Keyword(s):

Elevated Co2 ◽

Shoot Growth ◽

Co2 Enrichment ◽

Atmospheric Co2 ◽

Shoot Biomass ◽

Eucalyptus Tereticornis ◽

Growth Responses ◽

Ambient Conditions ◽

Long Distance ◽

Pipe Model

We report on the relationship between growth, partitioning of shoot biomass and hydraulic development of Eucalyptus tereticornis Sm. grown in glasshouses for six months. Close coordination of stem vascular capacity and shoot architecture is vital for survival of eucalypts, especially as developing trees are increasingly subjected to spasmodic droughts and rising atmospheric CO2 levels. Trees were exposed to constant soil moisture deficits in 45 L pots (30–50% below field capacity), while atmospheric CO2 was raised to 700 μL CO2 L–1 in matched glasshouses using a hierarchical, multi-factorial design. Enrichment with CO2 stimulated shoot growth rates for 12–15 weeks in well-watered trees but after six months of CO2 enrichment, shoot biomasses were not significantly heavier (30% stimulation) in ambient conditions. By contrast, constant drought arrested shoot growth after 20 weeks under ambient conditions, whereas elevated CO2 sustained growth in drought and ultimately doubled the shoot biomass relative to ambient conditions. These growth responses were achieved through an enhancement of lateral branching up to 8-fold due to CO2 enrichment. In spite of larger transpiring canopies, CO2 enrichment also improved the daytime water status of leaves of droughted trees. Stem xylem development was highly regulated, with vessels per unit area and cross sectional area of xylem vessels in stems correlated inversely across all treatments. Furthermore, vessel numbers related to the numbers of leaves on lateral branches, broadly supporting predictions arising from Pipe Model Theory that the area of conducting tissue should correlate with leaf area. Diminished water use of trees in drought coincided with a population of narrower xylem vessels, constraining hydraulic capacity of stems. Commensurate with the positive effects of elevated CO2 on growth, development and leaf water relations of droughted trees, the capacity for long-distance water transport also increased.

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The effect of constant and seasonal changes of ambient conditions on long-term behavior of high-rise concrete structures

The Structural Design of Tall and Special Buildings ◽

10.1002/tal.1548 ◽

2018 ◽

Vol 27 (18) ◽

pp. e1548 ◽

Cited By ~ 2

Author(s):

Mohammad Jalilzadeh Afshari ◽

Ali Kheyroddin ◽

Majid Gholhaki

Keyword(s):

Seasonal Changes ◽

Concrete Structures ◽

Ambient Conditions ◽

High Rise ◽

Long Term Behavior

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High sink strength prevents photosynthetic down-regulation in cassava grown at elevated CO2 concentration

Journal of Experimental Botany ◽

10.1093/jxb/eraa459 ◽

2020 ◽

Cited By ~ 2

Author(s):

Ursula M Ruiz-Vera ◽

Amanda P De Souza ◽

Michael R Ament ◽

Roslyn M Gleadow ◽

Donald R Ort

Keyword(s):

Elevated Co2 ◽

Leaf Tissue ◽

Co2 Enrichment ◽

Co2 Concentration ◽

Cultivar Differences ◽

Sink Strength ◽

Down Regulation ◽

Tropical Regions ◽

Free Air ◽

Intrinsic Water Use Efficiency

Abstract Cassava has the potential to alleviate food insecurity in many tropical regions, yet few breeding efforts to increase yield have been made. Improved photosynthetic efficiency in cassava has the potential to increase yields, but cassava roots must have sufficient sink strength to prevent carbohydrates from accumulating in leaf tissue and suppressing photosynthesis. Here, we grew eight farmer-preferred African cassava cultivars under free-air CO2 enrichment (FACE) to evaluate the sink strength of cassava roots when photosynthesis increases due to elevated CO2 concentrations ([CO2]). Relative to the ambient treatments, elevated [CO2] treatments increased fresh (+27%) and dry (+37%) root biomass, which was driven by an increase in photosynthesis (+31%) and the absence of photosynthetic down-regulation over the growing season. Moreover, intrinsic water use efficiency improved under elevated [CO2] conditions, while leaf protein content and leaf and root cyanide concentrations were not affected. Overall, these results suggest that higher cassava yields can be expected as atmospheric [CO2] increases over the coming decades. However, there were cultivar differences in the partitioning of resources to roots versus above-grown biomass; thus, the particular responses of each cultivar must be considered when selecting candidates for improvement.

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Population dynamics of Cymodocea nodosa under future ocean scenarios.

10.1101/484634 ◽

2018 ◽

Author(s):

Amrit K Mishra

Keyword(s):

Population Dynamics ◽

Elevated Co2 ◽

Marine Ecosystem ◽

Co2 Enrichment ◽

Cymodocea Nodosa ◽

Long Term Effects ◽

Leaf Production ◽

Co2 Concentrations ◽

Carbon Dioxide Co2

Rising carbon dioxide (CO2) concentrations in the atmosphere will increase the average pCO2 level in the world oceans, which will have a knock-on effect on the marine ecosystem. Coastal seagrass communities are predicted to benefit from the increase in CO2 levels, but long-term effects of elevated CO2 on seagrass communities are less understood. Population reconstruction techniques were used to investigate the population dynamics of Cymodocea nodosa meadows, exposed to long term elevated CO2 at volcanic seeps off Greece and Italy. Effect of elevated CO2 was noticed on the growth, morphometry, density, biomass and age structure at CO2 seeps than reference sites. Above to below ground biomass ratio of C. nodosa were higher at CO2 seeps. The shoot age and shoot longevity of plants were lower at seeps. The present recruitment (sampled year) of the seagrass were higher than long-term average recruitment of the communities near the seeps. Carbon to nitrogen ratios (%DW) and annual leaf production of C. nodosa were higher in leaves at seeps. This study suggests under long-term CO2 enrichment C. nodosa production increases, but the plant survival rate decreases because of other co-factors such as nutrient availability and trace metal toxicity. Therefore, along with high CO2 other factors must be taken into consideration while predicting effects of future CO2 concentrations.

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Effects of elevated CO2 on development and morphology of spring wheat grown in cooled and non-cooled open-top chambers

Functional Plant Biology ◽

10.1071/pp98016 ◽

1998 ◽

Vol 25 (5) ◽

pp. 617 ◽

Cited By ~ 11

Author(s):

M. van Oijen ◽

A.H.C.M. Schapendonk ◽

M.J.H. Jansen ◽

C.S. Pot ◽

J. van Kleef ◽

...

Keyword(s):

Elevated Co2 ◽

Spring Wheat ◽

Cooling System ◽

Co2 Concentration ◽

Triticum Aestivum L ◽

Ambient Conditions ◽

Morphological Response ◽

Open Top Chambers ◽

Temperature Interaction ◽

Doubled Co2 Concentration

Facilities for studying effects of elevated CO2 on crops affect the microclimate in the crop. Open-top chambers may increase temperature by 1–3˚C compared to ambient conditions. This paper describes a newly developed cooling system for open-top chambers. In 1995 and 1996, experiments were carried out to test the system and analyse the effects of temperature on crop phenological and morphological response to elevated CO2. Spring wheat (Triticum aestivum L. cv. Minaret) was subjected to ambient and doubled CO2 concentration in both cooled and non-cooled chambers. The cooling system reduced temperature by 1.6–2.4˚C, and this delayed maturity by 10 days. In contrast, elevated CO2 did not affect phenological development. Elevated CO2 reduced tiller density, green leaf number per tiller and specific leaf area, thereby reducing the capacity for light interception of the crop. Crop height growth before anthesis mainly responded to temperature, but after anthesis it was only affected by CO2, indicating a shift from sink- to source-limited growth. For none of the parameters studied, a significant statistical interaction of CO2 and temperature was found. The cooling system proved effective. Atemperature difference of about 2˚C affected crop development and morphology more strongly than CO2 doubling. However, the absence of CO2-temperature interaction suggests that CO2 effects may validly be investigated even without a cooling system.

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