scholarly journals Growth, leaf and stomatal traits of crabwood (Carapa guianensis Aubl.) in central Amazonia

2012 ◽  
Vol 36 (1) ◽  
pp. 07-16 ◽  
Author(s):  
Miguel Angelo Branco Camargo ◽  
Ricardo Antonio Marenco
Keyword(s):  
Growth Rates ◽  
Stomatal Density ◽  
Leaf Gas Exchange ◽  
Carbon Assimilation ◽  
Leaf Traits ◽  
Leaf Thickness ◽  
Diurnal Changes ◽  
Wet Season ◽  
Carapa Guianensis ◽  
Rainfall Seasonality

Crabwood (Carapa guianensis Aubl.) is a fast growing tree species with many uses among Amazonian local communities. The main objective of this study was to assess the effect of seasonal rainfall pattern on growth rates, and seasonal and diurnal changes in leaf gas exchange and leaf water potential (ΨL) in crabwood. To assess the effect of rainfall seasonality on growth and physiological leaf traits an experiment was conducted in Manaus, AM (03º 05' 30" S, 59º 59' 35" S). In this experiment, six 6-m tall plants were used to assess photosynthetic traits and ΨL. In a second experiment the effect of growth irradiance on stomatal density (S D), size (S S) and leaf thickness was assessed in 0.8-m tall saplings. Stomatal conductance (g s) and light-saturated photosynthesis (Amax) were higher in the wet season, and between 09:00 and 15:00 h. However, no effect of rainfall seasonality was found on ΨL and potential photosynthesis (CO2-saturated). ΨL declined from -0.3 MPa early in the morning to -0.75 MPa after midday. It increased in the afternoon but did not reach full recovery at sunset. Growth rates of crabwood were high, and similar in both seasons (2 mm month-1). Leaf thickness and S D were 19% and 47% higher in sun than in shade plants, whereas the opposite was true for S S. We conclude that ΨL greatly affects carbon assimilation of crabwood by reducing g s at noon, although this effect is not reflected on growth rates indicating that other factors offset the effect of g s on Amax.

Seasonal variation of carbon assimilation in mango (cv. Kensington Pride): effect of flowering treatments

2003 ◽  
Vol 54 (3) ◽  
pp. 309 ◽  
Author(s):  
Alonso González ◽  
S. J. Blaikie
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Leaf Gas Exchange ◽  
Average Rate ◽  
Carbon Assimilation ◽  
Vapour Pressure Deficit ◽  
Dry Season ◽  
Fruit Yield ◽  
Wet Season ◽  
The Tropics

In the tropics of northern Australia the mango cultivar Kensington Pride exhibits erratic flowering and fruiting and low productivity. Two treatments to manipulate flowering were applied. The first, mango flowering treatment (MFT), involved cutting a cincture through the bark around the circumference of the tree trunk and tying into the cincture a length of twine soaked in a solution of morphactin, CF125. The second involved applying paclobutrazol (PBZ) as a soil drench around the trunk of the tree. Phenology, leaf gas exchange, and fruit yield were assessed over 2 seasons in 3 separate groups of trees in commercial orchards near Darwin.Both MFT and PBZ supported earlier and/or more intense flowering in the season of application than did control trees. The PBZ was re-applied annually and the beneficial effect on flowering occurred in successive years. The MFT was applied once only at the start of the experiment and the effect of MFT was not evident in the second season.The effect of MFT on gas exchange was characterised by a severe reduction in net carbon assimilation (Amax), stomatal conductance (gs), and transpiration (E) for up to 4 months following treatment. Trees receiving PBZ generally had higher rates of leaf gas exchange than MFT trees but similar to control trees. During the dry season, leaves of MFT, control, and PBZ trees had similar rates of Amax. In the year of application, chlorophyll content of MFT trees was lower than that of the other treatments, but in the second year it was very similar to control trees. PBZ trees had the highest chlorophyll content during the study. Commercial fruit yield of PBZ-treated trees was 2–3 times higher than that of control or MFT trees. Independent of the flowering treatments, Amax followed a seasonal trend with an average rate of 9.05 μmol/m2.s (min. 4.42, max. 13.2) during the wet season (January–April), and 4.2 μmol/m2.s (min. 1.11, max. 8.7) during the dry season (May–October). Regression analysis demonstrated that 82% of the variation in gs and 76% of the variation in Amax could be explained by the effect of vapour pressure deficit of the leaf (VPDL) in field-grown mango trees.

Altitude of origin influences stomatal conductance and therefore maximum assimilation rate in Southern Beech, Nothofagus cunninghamii

2000 ◽  
Vol 27 (5) ◽  
pp. 451 ◽  
Author(s):  
Mark J. Hovenden ◽  
Tim Brodribb
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Density ◽  
Carbon Assimilation ◽  
Co2 Concentration ◽  
Carboxylation Efficiency ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate ◽  
Southern Beech ◽  
Maximum Stomatal Conductance ◽  
Leaf Biochemistry

Gas exchange measurements were made on saplings of Southern Beech, Nothofagus cunninghamii (Hook.) Oerst. collected from three altitudes (350, 780 and 1100 m above sea level) and grown in a common glasshouse trial. Plants were grown from cuttings taken 2 years earlier from a number of plants at each altitude in Mt Field National Park, Tasmania. Stomatal density increased with increasing altitude of origin, and stomatal con-ductance and carbon assimilation rate were linearly related across all samples. The altitude of origin influenced thestomatal conductance and therefore carbon assimilation rate, with plants from 780 m having a greater photosynthetic rate than those from 350 m. The intercellular concentration of CO2 as a ratio of external CO2 concentration (ci/ca) was similar in all plants despite the large variation in maximum stomatal conductance. Carboxylation efficiency was greater in plants from 780 m than in plants from 350 m. Altitude of origin has a strong influence on the photo-synthetic performance of N. cunninghamii plants even when grown under controlled conditions, and this influence is expressed in both leaf biochemistry (carboxylation efficiency) and leaf morphology (stomatal density).

scholarly journals Branch elongation and diameter growth were temporally dissociatedin "cerrado" tree species

Hoehnea ◽  
2009 ◽  
Vol 36 (3) ◽  
pp. 437-444 ◽  
Author(s):  
Davi Rodrigo Rossatto
Keyword(s):  
Water Status ◽  
Carbon Assimilation ◽  
Dry Season ◽  
Diameter Growth ◽  
Wet Season ◽  
Dry Period ◽  
Central Brazil ◽  
Branch Growth ◽  
Tree Community ◽  
One Year

Here is a communicating about time differences between branch and diameter growth in a tree community of ten species in Neotropical savanna ("cerrado") of Central Brazil. This work was conducted to study branch expansion and diameter growth in a period of one year between 2006 and 2007. Branch growth had begin in middle dry season and had the peak occurrence during the dry period in September, while diameter growth had begin in late dry season and peaked in the middle of wet season in December. The majority of species followed the same pattern. Branch growth did not have relation with rainfall, while diameter growth had a clear and positive relation with rainfall records. These results suggested that branch growth was not depend on rainfall but only on water status recover, while diameter growth probably depends strongly on water and to carbon assimilation that occurs after branch and leaf expansion.

Differences in morpho-physiological leaf traits reflect the response of growth to drought in a seeder but not in a resprouter Mediterranean species

2012 ◽  
Vol 39 (4) ◽  
pp. 332 ◽  
Author(s):  
David A. Ramírez ◽  
Antonio Parra ◽  
Víctor Resco de Dios ◽  
José M. Moreno
Keyword(s):  
Water Availability ◽  
Isotope Composition ◽  
Carbon Assimilation ◽  
Late Summer ◽  
Leaf Traits ◽  
Severe Drought ◽  
Photosynthetic Gas Exchange ◽  
Maximum Water ◽  
Monthly Changes ◽  
Projected Changes

Understanding the mechanisms underlying the response of different plant functional types to current and projected changes in rainfall is particularly important in drought-prone areas like the Mediterranean. Here, we report the responses of two species with contrasting leaf characteristics and post-fire regeneration strategies (Cistus ladanifer L., malacophyllous, seeder; Erica arborea L., sclerophyllous, resprouter) to a manipulative field experiment that simulated a severe drought (45% reduction of historical average rainfall). We measured monthly changes in relative growth rate (RGR), specific leaf area (SLA), bulk leaf carbon isotope composition (δ13C), predawn water potential (Ψpd), photosynthetic gas exchange, bulk modulus of elasticity and osmotic potential at maximum turgor (π). Temporal (monthly) changes in RGR of C. ladanifer were correlated with all measured leaf traits (except π) and followed Ψpd variation. However, the temporal pattern of RGR in E. arborea was largely unrelated to water availability. SLA monthly variation reflected RGR variation reasonably well in C. ladanifer, but not in E. arborea, in which shoot growth and δ13C increased at the time of maximum water stress in late summer. The relationship between water availability, and RGR and carbon assimilation in C. ladanifer, and the lack of any relationship in E. arborea suggest that the former has an enhanced capacity to harness unpredictable rainfall pulses compared with the latter. These contrasting responses to water availability indicate that the projected changes in rainfall with global warming could alter the competitive ability of these two species, and contribute to changes in plant dominance in Mediterranean shrublands.

scholarly journals Leaf traits and gas exchange in saplings of native tree species in the Central Amazon

2010 ◽  
Vol 67 (6) ◽  
pp. 624-632 ◽  
Author(s):  
Keila Rego Mendes ◽  
Ricardo Antonio Marenco
Keyword(s):  
Gas Exchange ◽  
Nitrogen Content ◽  
Leaf Area ◽  
Tree Species ◽  
Leaf Traits ◽  
Leaf Nitrogen ◽  
Dry Season ◽  
Leaf Thickness ◽  
Rainfall Regime ◽  
Leaf Nitrogen Content

Global climate models predict changes on the length of the dry season in the Amazon which may affect tree physiology. The aims of this work were to determine the effect of the rainfall regime and fraction of sky visible (FSV) at the forest understory on leaf traits and gas exchange of ten rainforest tree species in the Central Amazon, Brazil. We also examined the relationship between specific leaf area (SLA), leaf thickness (LT), and leaf nitrogen content on photosynthetic parameters. Data were collected in January (rainy season) and August (dry season) of 2008. A diurnal pattern was observed for light saturated photosynthesis (Amax) and stomatal conductance (g s), and irrespective of species, Amax was lower in the dry season. However, no effect of the rainfall regime was observed on g s nor on the photosynthetic capacity (Apot, measured at saturating [CO2]). Apot and leaf thickness increased with FSV, the converse was true for the FSV-SLA relationship. Also, a positive relationship was observed between Apot per unit leaf area and leaf nitrogen content, and between Apot per unit mass and SLA. Although the rainfall regime only slightly affects soil moisture, photosynthetic traits seem to be responsive to rainfall-related environmental factors, which eventually lead to an effect on Amax. Finally, we report that little variation in FSV seems to affect leaf physiology (Apot) and leaf anatomy (leaf thickness).

scholarly journals Effects of microhabitat on leaf traits in Digitalis grandiflora L. (Veronicaceae) growing at forest edge and interior

2014 ◽  
Vol 66 (2) ◽  
pp. 615-627
Author(s):  
J. Kołodziejek
Keyword(s):  
Soil Moisture ◽  
Leaf Area ◽  
Stomatal Density ◽  
Leaf Traits ◽  
Dry Mass ◽  
Forest Edge ◽  
Leaf Mass Per Area ◽  
Forest Interior ◽  
The Mean ◽  
Shade Leaves

The morphological, anatomical and biochemical traits of the leaves of yellow foxglove (Digitalis grandiflora Mill.) from two microhabitats, forest interior (full shade under oak canopy) and forest edge (half shade near shrubs), were studied. The microhabitats differed in the mean levels of available light, but did not differ in soil moisture. The mean level of light in the forest edge microhabitat was significantly higher than in the forest interior. Multivariate ANOVA was used to test the effects of microhabitat. Comparison of the available light with soil moisture revealed that both factors significantly influenced the morphological and anatomical variables of D. grandiflora. Leaf area, mass, leaf mass per area (LMA), surface area per unit dry mass (SLA), density and thickness varied greatly between leaves exposed to different light regimes. Leaves that developed in the shade were larger and thinner and had a greater SLA than those that developed in the half shade. In contrast, at higher light irradiances, at the forest edge, leaves tended to be thicker, with higher LMA and density. Stomatal density was higher in the half-shade leaves than in the full-shade ones. LMA was correlated with leaf area and mass and to a lesser extent with thickness and density in the forest edge microsite. The considerable variations in leaf density and thickness recorded here confirm the very high variation in cell size and amounts of structural tissue within species. The leaf plasticity index (PI) was the highest for the morphological leaf traits as compared to the anatomical and biochemical ones. The nitrogen content was higher in the ?half-shade leaves? than in the ?shade leaves?. Denser leaves corresponded to lower nitrogen (N) contents. The leaves of plants from the forest edge had more potassium (K) than leaves of plants from the forest interior on an area basis but not on a dry mass basis; the reverse was true for phosphorus.

scholarly journals Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

2016 ◽  
Author(s):  
Micael A. Cecchini ◽  
Luiz A. T Machado ◽  
Jennifer M. Comstock ◽  
Fan Mei ◽  
Jian Wang ◽  
...  
Keyword(s):  
Growth Rates ◽  
Urban Pollution ◽  
Droplet Size Distribution ◽  
Bimodal Distribution ◽  
Anthropogenic Sources ◽  
Cloud Base ◽  
Effective Diameter ◽  
Wet Season ◽  
Coalescence Process ◽  
Microphysical Properties

Abstract. The remote atmosphere over the Amazon can be similar to oceanic regions in terms aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analyzing observations of the interactions between Manaus city and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed period corresponds to the wet season over a tropical rain forest (i.e., Feb to Mar 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5), and the droplets observed are in the range 1 μm ≤ D ≤ 50 μm. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds compared to those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have lower effective diameters and higher droplet number concentrations. The average differences range from 10% to 40% for the effective diameter and are as high as 1000% for droplet concentration across different vertical levels (0 to 3200 m). The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 μm km-1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger d roplets (e.g., > 20 μm) close to cloud base, which would contribute significantly to the growth rates through the collision-coalescence process. The droplet size distribution (DSD) overall shape do not appear to be predominantly determined by updraft strength, especially beyond the 20 μm range. The aerosol conditions play a major role in that case. However, the updrafts modulate the DSD concentrations and are responsible for the vertical transport of water in the cloud. The larger droplets found in background clouds are associated with weak water vapour competition and a bimodal distribution of droplets in the lower levels of the cloud, that enables an earlier initiation of collision-coalescence process. This study shows that the pollution produced by Manaus affects significantly warm-phase microphysical properties of the surrounding clouds by changing the initial DSD formation. The corresponding effects on ice-phase processes and precipitation formation should be the focus of future endeavors.

Photosynthetic response of geranium to elevated CO2 as affected by leaf age and time of CO2 exposure

1991 ◽  
Vol 69 (11) ◽  
pp. 2482-2488 ◽  
Author(s):  
D. W. Kelly ◽  
P. R. Hicklenton ◽  
E. G. Reekie
Keyword(s):  
Stomatal Density ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Leaf Thickness ◽  
Middle Aged ◽  
Future Studies ◽  
Structural Modifications ◽  
Young Leaves ◽  
Developmental Characteristics ◽  
Density Results

Geranium plants were grown from seed in chambers maintained at 350 or 1000 μL∙L−1 CO2. Phtopsynthesis as affected by leaf age and by leaf position was determined. Elevated CO2 enhanced photosynthesis to the greatest extent in middle-aged leaves; very young leaves exhibited little enhancement, and net photosynthesis in the oldest leaves was depressed by elevated CO2. Temporary increases in net photosynthesis (relative to leaves developed at high CO2) resulted when young leaves grown at 350 μL∙L−1 CO2 were switched to 1000 μL∙L−1 CO2. Leaves switched later in development exhibited permanent enhancement. Middle-aged leaves exhibited a temporary depression followed by permanent enhancement. Leaves developed at high CO2 and switched to low CO2 did not exhibit any photosynthetic depression relative to plants grown continuously at low CO2. Similarly, leaves developed at low CO2, switched to high CO2 for various lengths of time, and returned to low CO2 showed no photosynthetic depression. Leaves developed at low CO2 and switched to high CO2 exhibited increases in specific leaf weight and leaf thickness. The increase in leaf thickness was proportional to length of time spent at high CO2. High CO2 depressed the rate at which stomata developed but did not affect final stomatal density. Results suggest that photosynthesis at low CO2 was limited by CO2 regardless of developmental environment, whereas photosynthesis at high CO2 was limited by the developmental characteristics of the leaf. Further, both biochemical and structural modifications appear to be involved in this response. Because of the very different responses of young versus old leaves, future studies should be careful to consider leaf age in assessing response to elevated CO2. Key words: carbon dioxide, elevated CO2, photosynthesis, geranium.

Effect of irrigation on leaf gas exchange and yield of cashew in northern Australia

1996 ◽  
Vol 36 (7) ◽  
pp. 861 ◽  
Author(s):  
H Schaper ◽  
EK Chacko ◽  
SJ Blaikie
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Water Deficit ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Northern Australia ◽  
Wet Season ◽  
Leaf Water Status ◽  
Continuous Irrigation ◽  
Tropical Regions

Gas exchange, leaf water status, soil water use and nut yield of cashew trees were monitored during the reproductive phase in 2 consecutive years (1988 and 1989). Treatment 1 comprised continuous irrigation from the end of the wet season in April until harvest in October; T2, irrigation between flowering (mid June) and harvest; and T3, no irrigation. Irrigation was applied by under-tree sprinkler at 43 mm/week in 1988 and 64 mm/week in 1989. Measurement of leaf gas exchange, chlorophyll content and nut production showed that trees in T2 were as productive as those in T1 (>1.3 kg kernel/tree). In T3, water deficit caused a 4-fold reduction in leaf photosynthesis and reduced leaf chlorophyll content from about 600 to 400 mg/m2 during fruit development. There was no effect on the number of hermaphrodite flowers produced (both ranging from 0 to 15 hermaphrodite flowers/panicle) but the water deficit was associated with a lower kernel yield (1.16 kg kernel/tree). Commercial yields (kg kernel/tree) in irrigated treatments were 20% greater than in the non-irrigated treatment and the kernels from irrigated trees were of a higher grade (kernel recovery >32% in T1 and T2 compared with 27.4% in T3). These results suggest that irrigation of established cashew plantations in the tropical regions of northern Australia can be restricted to the period between flowering and harvest without reducing yield.

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