Rising [CO2] changes competition relationships between native woody and alien herbaceous Cerrado species

2018 ◽  
Vol 45 (8) ◽  
pp. 854 ◽  
Author(s):  
Nayara M. J. Melo ◽  
Rayete S.-E. G. Rosa ◽  
Eduardo G. Pereira ◽  
João Paulo Souza
Keyword(s):  
Leaf Area ◽  
Elevated Co2 ◽  
Leaf Gas Exchange ◽  
Woody Species ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Growth Patterns ◽  
Grass Species ◽  
Herbaceous Species ◽  
Ecophysiological Responses

The structure of the Cerrado may be explained by the competition between woody and herbaceous species. However, the rising CO2 concentration ([CO2]) predicted under current climatic change may modify the ecophysiological responses of woody and herbaceous species owing to functional traits of each group, which may in turn modify vegetation structure as competitive relationships change among species. In this study we examined ecophysiological responses and competition between two cerrado species under elevated [CO2]. We selected an herbaceous alien grass (Melinis minutiflora P. Beauv.) and an endemic woody cerrado species (Hymenaea stigonocarpa Mart. ex Hayne). Hymenaea stigonocarpa individuals were maintained in three plots with different M. minutiflora densities: 0, 50 and 100% in two different [CO2] (380 ppm and 700 ppm) in open-top chambers. Leaf gas exchange, effective quantum efficiency of PSII, chlorophyll content, and growth increased in H. stigonocarpa plants under high [CO2]. The competition with M. minutiflora under elevated [CO2] led to an increase in specific leaf area, leaf area ratio and biomass allocation to shoots in H. stigonocarpa. In contrast, M. minutiflora had a delayed leaf development and high stem dry mass under elevated [CO2]. These changes in growth patterns under elevated [CO2] will modify allocation of resources, improving the competition potential of the woody species over the alien grass species in the Cerrado.

The impact of elevated atmospheric CO2 and nitrate supply on growth, biomass allocation, nitrogen partitioning and N2 fixation of Acacia melanoxylon

1999 ◽  
Vol 26 (8) ◽  
pp. 737 ◽  
Author(s):  
Marcus Schortemeyer ◽  
Owen K. Atkin ◽  
Nola McFarlane ◽  
John R. Evans
Keyword(s):  
Elevated Co2 ◽  
N2 Fixation ◽  
Dry Matter ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Nitrogen Partitioning ◽  
Atmospheric Co2 ◽  
Acacia Melanoxylon ◽  
Nitrate Supply ◽  
The Impact

The interactive effects of nitrate supply and atmospheric CO2 concentration on growth, N2 fixation, dry matter and nitrogen partitioning in the leguminous tree Acacia melanoxylon R.Br. were studied. Seedlings were grown hydroponically in controlled-environment cabinets for 5 weeks at seven 15N-labelled nitrate levels, ranging from 3 to 6400 mmol m–3. Plants were exposed to ambient (~350 µmol mol–1) or elevated (~700 µmol mol–1) atmospheric CO2 for 6 weeks. Total plant dry mass increased strongly with nitrate supply. The proportion of nitrogen derived from air decreased with increasing nitrate supply. Plants grown under either ambient or elevated CO2 fixed the same amount of nitrogen per unit nodule dry mass (16.6 mmol N per g nodule dry mass) regardless of the nitrogen treatment. CO2 concentration had no effect on the relative contribution of N2 fixation to the nitrogen yield of plants. Plants grown with ≥50 mmol m–3 N and elevated CO2 had approximately twice the dry mass of those grown with ambient CO2 after 42 days. The rates of net CO2 assimilation under growth conditions were higher per unit leaf area for plants grown under elevated CO2. Elevated CO2 also decreased specific foliage area, due to an increase in foliage thickness and density. Dry matter partitioning between plant organs was affected by ontogeny and nitrogen status of the plants, but not by CO2 concentration. In contrast, plants grown under elevated CO2 partitioned more of their nitrogen to roots. This could be attributed to reduced nitrogen concentrations in foliage grown under elevated CO2.

scholarly journals Differential Growth Responses of Wheat Seedlings to Elevated CO2

2018 ◽  
Vol 10 (3) ◽  
pp. 400-409 ◽  
Author(s):  
Hamid Reza ESHGHIZADEH ◽  
Morteza ZAHEDI ◽  
Samaneh MOHAMMADI
Keyword(s):  
Leaf Area ◽  
Plant Height ◽  
Elevated Co2 ◽  
Co2 Concentration ◽  
Tolerance Index ◽  
Dry Matter Accumulation ◽  
Wheat Cultivars ◽  
Growth Responses ◽  
Differential Growth ◽  
Wheat Seedlings

Intraspecific variations in wheat growth responses to elevated CO2 was evaluated using 20 Iranian bread wheat (Triticum aestivum L.) cultivars. The plants were grown in the modified Hoagland nutrient solution at a greenhouse until 35 days of age using two levels of CO2 (~380 and 700 µmol mol–1). The shoot and root dry weights of the wheat cultivars exhibited average enhancements of 17% and 36%, respectively, under elevated CO2. This increase was associated with higher levels of chlorophyll a (25%), chlorophyll b (21%), carotenoid (30%), leaf area (54%) and plant height (49.9%). The leaf area (r = 0.69**), shoot N content (r = 0.62**), plant height (r = 0.60**) and root volume (r = 0.53*) were found to have important roles in dry matter accumulation of tested wheat cultivars under elevated CO2 concentration. However, responses to elevated CO2 were considerably cultivar-dependent. Based on the stress susceptibility index (SSI) and stress tolerance index (STI), the wheat cultivars exhibiting the best response to elevated CO2 content were ‘Sistan’, ‘Navid’, ‘Shiraz’, ‘Sepahan’ and ‘Bahar’, while the ones with poor responses were ‘Omid’, ‘Marun’, ‘Sorkhtokhm’ and ‘Tajan’. The findings from the present experiment showed significant variation among the Iranian wheat cultivars in terms of their responses to elevated air CO2, providing the opportunity to select the most efficient ones for breeding purposes.

scholarly journals Carboxylation Capacity Can Limit C3 Photosynthesis at Elevated CO2 throughout Diurnal Cycles

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2603
Author(s):  
James Bunce
Keyword(s):  
Elevated Co2 ◽  
Carbon Fixation ◽  
Leaf Gas Exchange ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Early Morning ◽  
C3 Plants ◽  
Lablab Purpureus ◽  
Diurnal Cycles ◽  
Air Temperatures

The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 min using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 μmol mol−1 and one at 600 μmol mol−1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J. The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.

scholarly journals Growth responses of light demanding and shade tolerant peat swamp forest saplings to elevated CO2

2021 ◽  
Vol 42 (3(SI)) ◽  
pp. 735-743
Author(s):  
M.N.L. Wahidah ◽  
◽  
M.S. Nizam ◽  
C.M.Z. Che Radziah ◽  
W.A. Wan Juliana ◽  
...  
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Elevated Co2 ◽  
Co2 Concentration ◽  
Growth Responses ◽  
Swamp Forest ◽  
Relative Growth ◽  
Peat Swamp Forest ◽  
Elevated Atmospheric Co2

Aim: To determine the growth responses of two peat swamp forest species, Shorea platycarpa, a shade-tolerant slow-growing species and Macaranga pruinosa, a light-demanding fast-growing species under elevated atmospheric CO2 concentration. Methodology: The saplings of both species were grown in a shade house at ambient (400±50 µmol mol-1) and in an open roof ventilation greenhouse at elevated atmospheric CO2 concentration 800±50 µmol mol-1 for seven months. The temperature in both environments ranged between 25-33°C with 55–60% sunlight transmittance and the saplings were thoroughly watered twice a day. Plants growth measurements were estimated at frequent intervals. Saplings biomass characteristics were examined using destructive methods after seven months of treatment and non-destructive method was used for determination of leaf area. Results: Elevated CO2 enhanced all the growth characteristics in M. pruinosa with a significant increase was observed particularly on both height and diameter relative growth rate and biomass characteristics. The height relative growth rate and leaf area were significantly reduced under elevated CO2 in S. platycarpa but did not affect the shoot or root diameter and biomass significantly. A positive correlation (r =0.77, p>0.05) between stem biomass and basal diameter for plants under elevated CO2 was recorded for M. pruinosa, but not in S. platycarpa. Both species showed negative correlation (S. platycarpa; r = -0.53, M. pruinosa; r = -0.46, p>0.05) between stem growth and stem biomass at elevated CO2. Interpretation: These results unveiled profound effects of elevated CO2 on the growth of light-demanding species M. pruinosa, while shade-tolerant species S. platycarpa was not relatively affected by elevated CO2. This underscored the necessity to analyse different species performance to elevated CO2, thereby improving the ability to predict tropical swamp forest ecosystem responses to rising CO2.

scholarly journals Carboxylation Capacity Can Limit Photosynthesis at Elevated CO2 throughout Diurnal Cycles

2021 ◽  
Author(s):  
James Bunce
Keyword(s):  
Elevated Co2 ◽  
Carbon Fixation ◽  
Leaf Gas Exchange ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Early Morning ◽  
C3 Plants ◽  
Lablab Purpureus ◽  
Diurnal Cycles ◽  
Air Temperatures

The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 minutes using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 mol mol-1 and one at 600 mol mol-1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J, The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.

scholarly journals Productive and physiological responses of jambu (Acmella oleracea) under nutrient concentrations in nutrient solution

2021 ◽  
Vol 39 (1) ◽  
pp. 65-71
Author(s):  
Italo MG Sampaio ◽  
Mário L Silva Júnior ◽  
Ricardo FPM Bittencourt ◽  
Gabriel AM dos Santos ◽  
Fiama KM Nunes ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Nutrient Solution ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Ionic Concentration ◽  
Stem Diameter ◽  
Internal Co2 Concentration ◽  
Internal Co2 ◽  
Fresh And Dry Mass

ABSTRACT In the last years, jambu has become popular and greatly appreciated, due to its remarkable taste. Thus, hydroponically cultivated jambu is promising, since it achieves better yield and production quality. The aim of this study was to evaluate the effect of ionic concentration in nutrient solution on growth, productivity and gas exchange of jambu. The experimental design was completely randomized, with five treatments and four replicates. The treatments consisted of variations of ionic concentration using the nutrient solution proposed by Hoagland & Arnon (25, 50, 75, 100 and 125%). The length of the main stem, stem diameter, number of inflorescence, leaf area, fresh and dry biomass (shoot, root and inflorescence), photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, Ci/Ca ratio and instant carboxylation efficiency were evaluated. Ionic concentrations significantly affected the studied variables, except the stem diameter, the internal CO2 concentration and the Ci/Ca ratio. The number of inflorescences and the leaf area grew linearly with maximum values (37.8 units plant-1 and 1650.8 cm2 plant-1, respectively) obtained in ionic concentration of 125%. Maximum responses were observed for shoot fresh and dry mass (63.9 and 6.9 g plant-1), root fresh and dry mass (16.7 and 2.0 g plant-1) inflorescence fresh and dry mass (11.0 and 1.8 g plant-1), respectively, at ionic concentration of 125%. Liquid photosynthesis, stomatal conductance, transpiration and instant carboxylation efficiency achieved maximum responses of 17.9 µmol CO2 m-2 s-1, 0.3 mol H2O m-2 s-1, 6.3 mmol m-2 s-1 and 0.06 with estimated concentrations of 84, 70, 80 and 83% of ionic strength, respectively. Thus, we concluded that the ionic concentration of 125% is indicated to obtain a greater biomass accumulation.

Gas Exchange and Nitrogen Compartmentalization of Eggplant under Nitrogen and Silicon Doses

2019 ◽  
pp. 1-8
Author(s):  
Ewerton Gonçalves de Abrantes ◽  
Josinaldo Lopes Araujo Rocha ◽  
Kariolania Fortunato De Paiva ◽  
Railene Hérica Carlos Rocha ◽  
Alexandre Paiva da Silva ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetic Rate ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Nitrogen Accumulation ◽  
Area Index ◽  
Associated Variables

To evaluate the effect of fertilization with N and Si on gaseous exchanges, dry mass, concentrations, accumulations and compartmentalization of nitrogen fractions in eggplant. The experimental design was a randomized entirely design, in a 5 x 4 factorial arrangement with four replications and one plant per plot, totaling 80 experimental units. The experiment was conducted in a protected environment at Center of Sciences and Agri-Food Technology of the Federal University of Campina Grande, Campus of Pombal, Paraiba, Brazil, between July and September 2016. The nitrogen doses applied was 25, 125, 250, 350 and 500 mg dm-3 and four silicon doses was 0, 75, 150 and 200 mg dm-3 both supplied by root. In pre-flowering stage were evaluated growth components; gas exchange, which are: photosynthesis, stomatal conductance, transpiration rate and intercellular CO2 concentration; levels and accumulation of fractions of nitrogen (NO3-, NH4+, and total), and the silicon concentration in the leaves. There was no significant interaction (p >0.05) between the factors nitrogen and silicon doses for any of the evaluated variables. Nitrogen and silicon doses influenced the variables evaluated only independently each other. The nitrogen doses promoted increases in the photosynthetic rate and associated variables, dry matter yield of stem leaves and roots and in the concentration and accumulations of nitric, ammoniacal and total nitrogen in leaf, stem e roots and decrease the concentration of silicon in leaves. The silicon doses increased the leaf area index, the nitrate levels and accumulation in the roots and the silicon content in the leaves. In conclusion, the nitrogen supply increased the photosynthetic rate, dry mass and nitrogen accumulation and decreased the concentrations of silicon in leaf. Silicon did not interfered with growth of eggplant, however increased leaf area index, decreased nitrate levels and accumulations in the roots at lower doses of this element.

scholarly journals Increased productivity of ryegrass grown at elevated CO2 is dependent on tillering and leaf area development rather than leaf-level photosynthesis

2020 ◽  
Author(s):  
Charilaos Yiotis ◽  
Jennifer C McElwain ◽  
Bruce A Osborne
Keyword(s):  
Leaf Area ◽  
Elevated Co2 ◽  
Growth Yield ◽  
Biomass Productivity ◽  
Co2 Concentration ◽  
Crop Productivity ◽  
Atmospheric Co2 ◽  
Leaf Photosynthesis ◽  
Diverse Range ◽  
Co2 Concentrations

Abstract Whilst a range of strategies have been proposed for enhancing crop productivity many recent studies have focussed primarily on enhancing leaf photosynthesis under current atmospheric CO2 concentrations. Given that the atmospheric CO2 concentration is likely to increase significantly in the foreseeable future an alternative/complementary strategy might be to exploit any variability in the enhancement of growth/yield and photosynthesis at higher CO2 concentrations. To explore this, we investigated the responses of a diverse range of wild and cultivated ryegrass genotypes, with contrasting geographical origins, to ambient and elevated CO2 concentrations and examined what genetically tractable plant trait(s) might be targeted by plant breeders for future yield enhancements. We found substantial ~7-fold intraspecific variations in biomass productivity among the different genotypes at both CO2 levels, which were related primarily to differences in tillering/leaf area, with only small differences due to leaf photosynthesis. Interestingly, the ranking of genotypes in terms of their response to both CO2 concentrations was similar. However, as expected, estimates of whole-plant photosynthesis were strongly correlated with plant productivity. Our results suggest that greater yield gains under elevated CO2 are likely through the exploitation of genetic differences in tillering and leaf area rather than focussing solely on improving leaf photosynthesis.

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