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.

Distribution of Trialeurodes vaporariorum and Bemisia tabaci (Homoptera: Aleyrodidae) on Some Greenhouse-grown Ornamental Plants

1993 ◽  
Vol 28 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Tong-Xian Liu ◽  
Ronald D. Oetting ◽  
G. David Buntin
Keyword(s):  
Bemisia Tabaci ◽  
Developmental Stages ◽  
Ornamental Plants ◽  
Leaf Age ◽  
Trialeurodes Vaporariorum ◽  
Middle Aged ◽  
Greenhouse Whitefly ◽  
Whole Plant ◽  
Young Leaves ◽  
The Vertical Distribution

The within-plant and between-plant distributions of all stages of both greenhouse whitefly (GHWF), Trialeurodes vaporariorum (Westwood) on poinsettia, chrysanthemum and gerbera daisy, and sweetpotato whitefly (SPWF), Bemisia tabaci (Gennadius) on poinsettia, were examined using Taylor's power law (s2 = amb) and Iwao's patchiness () methods. We found that all developmental stages of the two whitefly species on all plants examined were aggregated within and between plants. The vertical distribution of whitefly stages is stratified among leaves within the plant with respect to leaf age rather than relative height of the leaves on the plants. Most of the adults, eggs and the first-instar nymphs occurred on young leaves. The second- and third-instar nymphs occurred on middle-aged leaves, and most of the pupae and empty pupal cases occurred on middle-aged and older leaves. Comparison of whitefly counts from the different combinations of top, middle, and bottom leaves with the whole-plant counts on poinsettia was correlated and these leaves can be sampled as an indication of population levels within a greenhouse population.

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.

scholarly journals Meteorological conditions, ozone concentration and leaf age affect gas exchange in Psidium guajava ‛Palumaʼ

Hoehnea ◽  
2017 ◽  
Vol 44 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Juliana Moreno Pina ◽  
Sérgio Tadeu Meirelles ◽  
Regina Maria de Moraes
Keyword(s):  
Gas Exchange ◽  
Ozone Concentration ◽  
Leaf Age ◽  
Psidium Guajava ◽  
Meteorological Conditions ◽  
Gas Exchanges ◽  
Mature Leaves ◽  
Young Leaves ◽  
Entire Experiment ◽  
The City

ABSTRACT This study aimed to investigate the importance of leaf age, meteorological conditions and ozone concentration (O3) on gas exchange of Psidium guajava ‛Paluma'. Saplings were grown and exposed in standard conditions in the city of São Paulo, in six periods of three months with weekly measurements in young and mature leaves. Gas exchanges were higher in young leaves for almost the entire experiment. Mature leaves showed greater reduction in gas exchange. The multivariate analysis of biotic and abiotic variables indicated that vapor pressure deficit (VPD), O3 concentration and radiation were the main variables associated with gas exchange decrease in young leaves. In mature leaves the influence of VPD is lower, but the temperature importance is higher. Moreover, the opposition between assimilation and O3 is more evident in mature leaves, indicating their greater sensitivity to O3.

scholarly journals Distribution and pathogenicity of Pseudomonas cichorii (Swingle) Stapp in coffee in Puerto Rico

1969 ◽  
Vol 87 (3-4) ◽  
pp. 123-135 ◽  
Author(s):  
Luis Sánchez ◽  
Mildred Zapata ◽  
Rocío del P. Rodríguez ◽  
James S. Beaver
Keyword(s):  
Puerto Rico ◽  
Leaf Age ◽  
Coffea Canephora ◽  
Resistance Mechanisms ◽  
Pseudomonas Cichorii ◽  
Inoculation Methods ◽  
Young Leaves ◽  
Resistant Genotypes ◽  
Coffee Species

Seventeen pathogenic strains of Pseudomonas cichorii were isolated from leaf samples of coffee (Coffea arabica) collected from nurseries in eight municipalities of Puerto Rico. Two different inoculation methods were evaluated under in vitro conditions: inoculation of plant-attached old and young leaves grown under greenhouse conditions, and plant-detached young coffee leaves grown under field conditions. Pseudomonas cichorii was more virulent in older leaves, thus indicating that resistance mechanisms differ according to leaf age. Both inoculation methods were reliable in identifying resistant genotypes. Three commercial varieties of coffee (Borbón, Pacas and Caturra) were susceptible to bacterial leaf blight, whereas coffee species Coffea liberica var. Excelsa and Coffea canephora var. Robusta were resistant.

Stomatal Development During Leaf Expansion in Tobacco and Sunflower

1975 ◽  
Vol 23 (2) ◽  
pp. 253 ◽  
Author(s):  
HM Rawson ◽  
CL Craven
Keyword(s):  
Leaf Area ◽  
Stomatal Density ◽  
Stomatal Development ◽  
Developmental Patterns ◽  
Full Size ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Wide Range ◽  
Young Leaves ◽  
Different Levels

Changes in stomatal density and size were followed in tobacco and sunflower leaves expanding from 10% of final area (10% Amax) to Amax under different levels of radiation. Lower radiation increased final leaf area, reduced stomatal densities, and increased area per stoma but had little effect on stomatal area per unit leaf area at Amax. In very young leaves (20% Amax) there was a wide range in the sizes of individual stomata, some stomata being close to full size, but by Amax differences were small. The possible relationship between the developmental patterns described and photosynthesis is briefly discussed.

Canopy position affects photosynthesis and anatomy in mature Eucalyptus trees in elevated CO2

2020 ◽  
Author(s):  
K Y Crous ◽  
C Campany ◽  
R Lopez ◽  
F J Cano ◽  
D S Ellsworth
Keyword(s):  
Elevated Co2 ◽  
Anatomical Variation ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Leaf Mass Per Area ◽  
Mesophyll Conductance ◽  
Mature Leaves ◽  
Canopy Position ◽  
Palisade Cells

Abstract Leaves are exposed to different light conditions according to their canopy position, resulting in structural and anatomical differences with consequences for carbon uptake. While these structure–function relationships have been thoroughly explored in dense forest canopies, such gradients may be diminished in open canopies, and they are often ignored in ecosystem models. We tested within-canopy differences in photosynthetic properties and structural traits in leaves in a mature Eucalyptus tereticornis canopy exposed to long-term elevated CO2 for up to three years. We explored these traits in relation to anatomical variation and diffusive processes for CO2 (i.e., stomatal conductance, gs and mesophyll conductance, gm) in both upper and lower portions of the canopy receiving ambient and elevated CO2. While shade resulted in 13% lower leaf mass per area ratio (MA) in lower versus upper canopy leaves, there was no relationship between leaf Nmass and canopy gap fraction. Both maximum carboxylation capacity (Vcmax) and maximum electron transport (Jmax) were ~ 18% lower in shaded leaves and were also reduced by ~ 22% with leaf aging. In mature leaves, we found no canopy differences for gm or gs, despite anatomical differences in MA, leaf thickness and mean mesophyll thickness between canopy positions. There was a positive relationship between net photosynthesis and gm or gs in mature leaves. Mesophyll conductance was negatively correlated with mean parenchyma length, suggesting that long palisade cells may contribute to a longer CO2 diffusional pathway and more resistance to CO2 transfer to chloroplasts. Few other relationships between gm and anatomical variables were found in mature leaves, which may be due to the open crown of Eucalyptus. Consideration of shade effects and leaf-age dependent responses to photosynthetic capacity and mesophyll conductance are critical to improve canopy photosynthesis models and will improve understanding of long-term responses to elevated CO2 in tree canopies.

scholarly journals Differential responses between mature and young leaves of sunflower plants to oxidative stress caused by water deficit

2010 ◽  
Vol 40 (6) ◽  
pp. 1290-1294 ◽  
Author(s):  
Inês Cechin ◽  
Natália Corniani ◽  
Terezinha de Fátima Fumis ◽  
Ana Catarina Cataneo
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Leaf Age ◽  
Co2 Concentration ◽  
Mature Leaves ◽  
Young Leaves ◽  
Mda Content ◽  
Gas Exchange Characteristics

The effects of water stress and rehydration on leaf gas exchange characteristics along with changes in lipid peroxidation and pirogalol peroxidase (PG-POD) were studied in mature and in young leaves of sunflower (Helianthus annuus L.), which were grown in a greenhouse. Water stress reduced photosynthesis (Pn), stomatal conductance (g s), and transpiration (E) in both young and mature leaves. However, the amplitude of the reduction was dependent on leaf age. The intercellular CO2 concentration (Ci) was increased in mature leaves but it was not altered in young leaves. Instantaneous water use efficiency (WUE) in mature stressed leaves was reduced when compared to control leaves while in young stressed leaves it was maintained to the same level as the control. After 24h of rehydration, most of the parameters related to gas exchange recovered to the same level as the unstressed plants except gs and E in mature leaves. Water stress did not activated PG-POD independently of leaf age. However, after rehydration the enzyme activity was increased in mature leaves and remained to the same as the control in young leaves. Malondialdehyde (MDA) content was increased by water stress in both mature and young leaves. The results suggest that young leaves are more susceptible to water stress in terms of gas exchange characteristics than mature leaves although both went through oxidative estresse.

Is leaf age a predictor for cold tolerance in winter oilseed rape plants?

2020 ◽  
Vol 47 (3) ◽  
pp. 250 ◽  
Author(s):  
Ali Doǧru ◽  
Hüsnü Çakırlar
Keyword(s):  
Low Temperature ◽  
Oilseed Rape ◽  
Cold Exposure ◽  
Photosynthetic Activity ◽  
Leaf Age ◽  
Fluorescence Yield ◽  
Antioxidant Enzyme Activities ◽  
Winter Oilseed Rape ◽  
Fluorescence Measurements ◽  
Young Leaves

In the present study, low temperature-dependent physiological changes were investigated through photosynthetic activity and some endogenous mechanisms in two winter oilseed rape cultivars (Brassica napus L. ssp. oleifera cvv. Eurol and Hansen) on the basis of leaf age. Chlorophyll fluorescence measurements demonstrated that low temperature caused decreased photosynthetic activity in both cultivars. However, photosynthetic apparatus in the young leaves of Hansen is more tolerant to low temperature as demonstrated by lower F0 (minimum fluorescence yield) and 1–qp (excitation pressure of photosystem II), higher Fm (maximum fluorescence yield), Fv/Fm and non-photochemical quenching (NPQ) compared with Eurol. In addition, young leaves of Hansen represented marked increase in some antioxidant enzyme activities (superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR)) during cold exposure. In the young leaves of Eurol, however, APX and GR activity was decreased by low temperature, indicating lower efficiency of ascorbate-glutathione cycle. Lower antioxidant activity in the young leaves of Eurol may be responsible for increased malondialdehyde (MDA), H2O2 and membrane damage and decreased chlorophyll content as a result of oxidative damage during cold exposure. In the cold-stressed mature leaves, both cultivars represented similar antioxidant capacities and photosynthetic efficiency. As a consequence, coordinated increase in SOD, APX and GR activities, increased capacity to keep quinone A (QA) in an oxidised state (as indicated by lower 1–qp) and accumulation of soluble sugar and proline could be mainly attributed to higher level of tolerance of the young leaves of Hansen to low temperature when compared with Eurol.

Age groups changes in self-rated health: A prospective longitudinal study over a 20-year period using Health Survey of North Trøndelag data

2020 ◽  
pp. 140349482090462
Author(s):  
Frode Lysberg ◽  
Siw Tone Innstrand ◽  
Milada Cvancarova Småstuen ◽  
Cathrine Lysberg ◽  
Magnhild Mjåvatn Høie ◽  
...  
Keyword(s):  
Sex Differences ◽  
Health Survey ◽  
Age Groups ◽  
Older Age ◽  
Age Group ◽  
Middle Aged ◽  
Prospective Longitudinal Study ◽  
Future Studies ◽  
Self Rated Health ◽  
Prospective Longitudinal

Background: The aim of the study was to investigate changes in self-rated health (SRH) between different age groups and sexes over a 20-year period. Methods: Data were retrieved from the large longitudinal Health Survey of North Trøndelag, Norway, which includes data collected from more than 190,000 participants aged 20–70+ years between the years 1984 and 2008. Data were analysed using logistic regression and adjusted for sex. Results: From 1984 to 2008, the odds of scoring higher on SRH decreased by 46% in the youngest age group (20–29 years) and increased by approximately 35% in the middle-aged and older age groups (40–70+ years). When considering sex differences, women in most age groups scored lower than the men on their SRH. Conclusions: Our finding suggest a trending shift in SRH, with a reduction in the youngest age group (20–29 years) and an increase in the middle-aged and older age groups (40–70+ years). Despite the sex differences being small, our data indicate that in most age groups, women tend to score lower than men on their SRH. Future studies should focus on these trends to understand better the mechanisms underlying these changes in SRH and to follow future trends to see if the trend is reinforced or diminished.

Significant variation in the management of cull sows before transport for slaughter: results from a survey of Danish pig farmers

2020 ◽  
Vol 186 (6) ◽  
pp. 185-185 ◽  
Author(s):  
Mette S Herskin ◽  
Margit D Aaslyng ◽  
Inger Anneberg ◽  
Peter T Thomsen ◽  
Louisa M Gould ◽  
...  
Keyword(s):  
Animal Welfare ◽  
Questionnaire Survey ◽  
Significant Variation ◽  
Homogeneous Group ◽  
Middle Aged ◽  
Future Studies ◽  
Special Part ◽  
Cull Sows ◽  
Available Resources

BackgroundApproximately 50% of sows are slaughtered each year, but management of cull sows is not well described.MethodsWe aimed to describe how cull sows are sent to slaughter using a questionnaire survey emailed to 885 Danish pig farmers, including questions about the use of pick-up facilities (either a designated pen used for reasons of biosecurity and practicality, in a special part of the barn, where pigs are kept in the last hours before being loaded onto a commercial truck, or a stationary vehicle kept outside the buildings and used for the same purpose) and evaluation of fitness for transport.ResultsA total of 360 farmers answered all questions, constituting a homogeneous group of middle-aged, experienced males. The management of the sows seemed rather variable, for example regarding choice of pick-up facility, its available resources, actions taken when sows were not fit for transport and sow conditions leading to doubt about fitness for transport. Special condition transport was only reported rarely, and rejection of sows due to lack of fitness for transport, by drivers or veterinarians at the slaughterhouse, was only rarely experienced.ConclusionThese findings may be used for formulation of hypotheses for future studies in this area characterised by welfare challenges, potentially leading to science-based recommendations relevant for animal welfare, productivity and biosecurity.

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