Photosynthesis and Transpiration in Dicotyledonous Plants. I. Expanding Leaves of Tobacco and Sunflower.

1976 ◽  
Vol 3 (2) ◽  
pp. 247 ◽  
Author(s):  
HM Rawson ◽  
RG Woodward
Keyword(s):  
Growth Conditions ◽  
Relative Reduction ◽  
Co2 Uptake ◽  
Relative Importance ◽  
Tobacco Leaves ◽  
Leaf Emergence ◽  
Good Nutrition ◽  
Dicotyledonous Plants ◽  
Use Efficiency ◽  
Limited Period

The aims of this paper were (1) to determine if irradiance and nutrition influence the timing of peak photosynthesis (Fmax) in expanding tobacco Ieaves and (2) to assess the relative importance of stomatal (rs) and mesophyll (rm) resistances to CO2 uptake as leaves expand. Growth conditions affected rates of leaf expansion and final leaf areas (Amax) but not the time from leaf emergence to Amax (25 days). Patterns of photosynthesis with time were similar in all treatments-F rose rapidly to Fmax and then declined, and Fmax occurred on day 13 when the areas of leaves in different treatments were from 65-80 % Amax. We suggest that temperature may determine the timing of Fmax. Changes in both rs and rm were associated with changes in F prior to Fmax. Although changes in rm were up to five times greater than in rs during this period, the relative reduction in the two resistances was similar. Absolute changes in rs and rm were similar immediately after Fmax, and during this period of 7 days F declined by almost 50%. Thereafter, relative changes were closely matched. Possible mechanisms for the control of the resistances by the plant are discussed. We discuss the hypothesis that Fmax was maintained for only a limited period in expanding tobacco leaves because of the lack of a sink for assimilate. Expanding sunflower leaves maintained Fmax for a much longer period and reasons are presented for this different behaviour. Water use efficiency (ω) of tobacco leaves changed as they expanded and was greatest under good nutrition and poorest under low irradiance. Maximum ω for tobacco and sunflower was similar.

scholarly journals The effects of clouds and aerosols on net ecosystem CO<sub>2</sub> exchange over semi-arid Loess Plateau of Northwest China

2010 ◽  
Vol 10 (5) ◽  
pp. 13337-13372
Author(s):  
X. Jing ◽  
J. Huang ◽  
G. Wang ◽  
K. Higuchi ◽  
J. Bi ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Air Temperature ◽  
Northwest China ◽  
Co2 Uptake ◽  
Observation Data ◽  
Light Use Efficiency ◽  
Clearness Index ◽  
Use Efficiency ◽  
The Difference ◽  
Semi Arid

Abstract. The impacts of clouds and atmospheric aerosols on the terrestrial carbon cycle at semi-arid Loess Plateau in Northwest China are investigated, by using the observation data obtained at the SACOL (Semi-Arid Climate and Environment Observatory of Lanzhou University) site. Daytime (solar elevation angles of larger than 50°) NEE of CO2 obtained during the midgrowing season (July–August) are analyzed with respect to variations in the diffuse radiation, cloud cover and aerosol optical depth (AOD). Results show a significant impact by clouds and aerosols on the CO2 uptake by the grassland (with smaller LAI values) located in a semi-arid region, quite different from areas covered by forests and crops. The light saturation levels in canopy are lower, with a value of about 434.8 W m−2. Thus, under overcast conditions of optically thick clouds, the CO2 uptake increases with increasing clearness index, and a maximum CO2 uptake and light use efficiency of vegetation occur with the clearness index of about 0.37 and lower air temperature. Under other sky conditions the CO2 uptake decreases with the cloudiness but the light use efficiency is enhanced, due to increase in the fraction of diffuse PAR. Additionally, under cloudy conditions, changes in the NEE of CO2 also result from the interactions of many environmental factors, especially the air temperature. In contrast to its response to changes in solar radiation, the carbon uptake shows a negative response to increased AOD. The reason for the difference in the response of the semi-arid grassland from that of the forest and crop lands may be due to the difference in the canopy's architectural structure.

scholarly journals Generating Plants with Improved Water Use Efficiency

Agronomy ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 194 ◽  
Author(s):  
Sonja Blankenagel ◽  
Zhenyu Yang ◽  
Viktoriya Avramova ◽  
Chris-Carolin Schön ◽  
Erwin Grill
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Measurement Techniques ◽  
Growth And Yield ◽  
High Yield ◽  
Co2 Uptake ◽  
Crop Varieties ◽  
Leaf Level ◽  
Use Efficiency ◽  
Plant Level

To improve sustainability of agriculture, high yielding crop varieties with improved water use efficiency (WUE) are needed. Despite the feasibility of assessing WUE using different measurement techniques, breeding for WUE and high yield is a major challenge. Factors influencing the trait under field conditions are complex, including different scenarios of water availability. Plants with C3 photosynthesis are able to moderately increase WUE by restricting transpiration, resulting in higher intrinsic WUE (iWUE) at the leaf level. However, reduced CO2 uptake negatively influences photosynthesis and possibly growth and yield as well. The negative correlation of growth and WUE could be partly disconnected in model plant species with implications for crops. In this paper, we discuss recent insights obtained for Arabidopsis thaliana (L.) and the potential to translate the findings to C3 and C4 crops. Our data on Zea mays (L.) lines subjected to progressive drought show that there is potential for improvements in WUE of the maize line B73 at the whole plant level (WUEplant). However, changes in iWUE of B73 and Arabidopsis reduced the assimilation rate relatively more in maize. The trade-off observed in the C4 crop possibly limits the effectiveness of approaches aimed at improving iWUE but not necessarily efforts to improve WUEplant.

scholarly journals Yield analysis of Physalis ixocarpa Brot. ex Hornem varieties under greenhouse and field conditions

2018 ◽  
Vol 48 (11) ◽  
Author(s):  
Bernabé Ignacio Ramos-López ◽  
Yolanda Donaji Ortiz-Hernández ◽  
Isidro Morales
Keyword(s):  
Growth Conditions ◽  
Field Conditions ◽  
Matric Potential ◽  
Average Temperature ◽  
Large Plot ◽  
Small Plot ◽  
Use Efficiency ◽  
Average Relative Humidity ◽  
Husk Tomato ◽  
Soil Water Consumption

ABSTRACT: Physalis ixocarpa (husk tomato) is traditionally cultivated in Mexico, and nowadays the yield is low. In this study, four cultivars of husk tomato were evaluated, under greenhouse and field conditions. It was carried out a split-plot experimental design in a 4x2 factorial arrangement. The large plot was the growth conditions and the small plot was the variety. The microclimate, soil and yield variables were recorded. In the field, the Integrated Photosynthetic Active Radiation (IPAR) was higher 12mol m-2 d-1 than in the greenhouse. The average temperature was slightly higher 1.18°C in the greenhouse and the average relative humidity was slightly higher 0.89% in the field. Plants grown in the greenhouse had lower negative values for the matric potential of the soil. Water consumption and water use efficiency were 10.31 and 53.43% higher in the greenhouse that in the field, respectively. The number of fruits and yield increased significantly in all varieties grown under greenhouse conditions.

Estimating photosynthetic light-use efficiency using the photochemical reflectance index: variations among species

2004 ◽  
Vol 31 (3) ◽  
pp. 255 ◽  
Author(s):  
Jianmin Guo ◽  
Craig M. Trotter
Keyword(s):  
Light Response ◽  
Species Group ◽  
Photosynthetic Parameters ◽  
Co2 Uptake ◽  
Light Use Efficiency ◽  
Photochemical Reflectance Index ◽  
Response Data ◽  
Use Efficiency ◽  
Species Specific ◽  
The Relationship

Recent studies have shown that the photochemical reflectance index (PRI), derived from narrow waveband reflectance at 531 and 570 nm, can be used as a remote measure of photosynthetic light-use efficiency (LUE). However, uncertainty remains as to the consistency of the relationship between PRI and LUE across species. In this study we examined the relationship between the PRI and various photosynthetic parameters for a group of species with varying photosynthetic capacity. At constant irradiance, for the species group as a whole, the PRI was well correlated with LUE (r2=0.58) and with several other photosynthetic parameters, but best correlated with the ratio of carotenoids to chlorophylls contents (Caro / Chl). Despite the interspecific trends observed, determination of light response functions for the PRI in relation to photosynthetic parameters revealed that species-specific relationships were clearly stronger. For example, r2>0.90 for species-level PRI / LUE relationships. Also, the species-specific light-response data show that the magnitude of the PRI can be related to the magnitude of the saturated irradiance and the rate of CO2 uptake. As demonstrated here, a light response function provides a simple yet precise approach for characterising the relationship between the PRI and photosynthetic parameters, which should assist with improved evaluation of the usefulness of the PRI as a generalised measure of LUE.

Stable isotope fractionation by Clostridium pasteurianum. 4. Sulfur isotope fractionation during enzymatic S3O62−, S2O32−, and SO32− reductions

1981 ◽  
Vol 27 (8) ◽  
pp. 824-834
Author(s):  
G. I. Harrison ◽  
E. J. Laishley ◽  
H. R. Krouse
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Isotope Effects ◽  
Growth Conditions ◽  
Enzyme Concentration ◽  
Clostridium Pasteurianum ◽  
Relative Reduction ◽  
Stable Isotope Fractionation ◽  
Sulfur Isotope Fractionation

Cell-free extracts from Clostridium pasteurianum grown on SO32− utilize H2 to reduce S3O62−, S2O32−, and SO32− to H2S at a much faster rate than extracts from SO42−-grown cells. This further supports the concept of an inducible dissimilatory type SO32− reductive pathway in this organism. 35S dilution experiments further support the concept that S3O62− and S2O32− are pathway intermediates. The inducible SO32− reductase is ferredoxin linked and the kinetics of the reduction and the sulfur isotope fractionation of the product can be altered by altering the growth conditions. The attending sulfur isotope fractionations are similar to those observed during the chemical decomposition of these compounds. In the case of S2O32−, 35S labelling experiments verified the conclusions derived from the stable isotope fractionation data concerning the relative reduction rates of the sulfane and sulfonate sulfurs. The reduction rates were also affected by enzyme concentration. The integrity of the whole cell is a necessary requirement for the large inverse isotope effects previously reported.

scholarly journals Modeling light use efficiency in a subtropical mangrove forest equipped with CO<sub>2</sub> eddy covariance

2013 ◽  
Vol 10 (3) ◽  
pp. 2145-2158 ◽  
Author(s):  
J. G. Barr ◽  
V. Engel ◽  
J. D. Fuentes ◽  
D. O. Fuller ◽  
H. Kwon
Keyword(s):  
Eddy Covariance ◽  
Environmental Conditions ◽  
Mangrove Forest ◽  
Environmental Drivers ◽  
Model Parameters ◽  
Co2 Uptake ◽  
Light Use Efficiency ◽  
Co2 Fluxes ◽  
Use Efficiency ◽  
Reflectance Data

Abstract. Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC) systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE), and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt) increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and information about environmental conditions.

scholarly journals Post-flowering biotic and abiotic stresses impact nitrogen use efficiency and seed filling in Arabidopsis thaliana

2020 ◽  
Vol 71 (15) ◽  
pp. 4578-4590 ◽  
Author(s):  
Anne Marmagne ◽  
Sophie Jasinski ◽  
Mathilde Fagard ◽  
Laurence Bill ◽  
Philippe Guerche ◽  
...  
Keyword(s):  
Seed Yield ◽  
Growth Conditions ◽  
Climate Impacts ◽  
Plant Responses ◽  
Seed Composition ◽  
Seed Filling ◽  
N Remobilization ◽  
Use Efficiency ◽  
The Impact ◽  
C:N Stoichiometry

Abstract Nitrogen (N) is an essential nutrient that plants require for the synthesis of amino acids, proteins, and many other important metabolites. Plant metabolism and growth are consequently dependent on the amount of N that is assimilated and distributed from source leaves to developing sinks, such as fruits and seeds. The environmental stresses enhanced by climate change deeply influence seed yield and seed composition, and may disturb N use efficiency (NUE) in pants. We aimed to investigate plant responses to extreme climates with regard to NUE, N remobilization efficiency, and seed composition. By studying a collection of Arabidopsis genotypes showing a range of C:N ratios in seeds, we investigated the impact of different post-flowering growth conditions (control, heat, drought, low nitrate availability, induced senescence, and induced plant defense) on seed yield, N allocation in organs, NUE, and N remobilization efficiency. We analysed how post-flowering stresses could change seed filling and showed that post-flowering stresses change both the range of N and C concentrations and the C:N stoichiometry in seeds. Using a new trait, called delta seed composition, we measured the deviation in C:N stoichiometry of each genotype and revealed the genetic determinism of the C:N stoichiometry. Altogether, the results indicate that extreme climate impacts NUE dramatically in plants and generates different bottlenecks in N fluxes during seed filling.

Natural variation in stomatal dynamics drives divergence in heat stress tolerance and contributes to the seasonal intrinsic water-use efficiency in Vitis vinifera (subsp. sativa and sylvestris)

2021 ◽  
Author(s):  
Michele Faralli ◽  
Luana Bontempo ◽  
Pier Luigi Bianchedi ◽  
Claudio Moser ◽  
Massimo Bertamini ◽  
...  
Keyword(s):  
Heat Stress ◽  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Closure ◽  
Critical Role ◽  
Evaporative Cooling ◽  
Co2 Uptake ◽  
Stomatal Behavior ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Abstract Stomata control CO2 uptake for photosynthesis and water loss through transpiration, thus playing a key role in leaf thermoregulation, water-use efficiency (iWUE) and plant productivity. In this work, we investigated the relationship between several leaf traits and hypothesized that stomatal behavior to fast (i.e. minutes) environmental changes co-determines along with steady-state traits the physiological response of grapevine to the surrounding fluctuating environment over the growing season. No relationship between iWUE, heat stress (HS) tolerance and stomatal traits was observed in field grown grapevine, suggesting that other physiological mechanisms are involved in determining leaf evaporative cooling capacity and the seasonal ratio of CO2 uptake (A) to stomatal conductance (gs). Indeed, cultivars that in the field had an unexpected combination of high iWUE but low sensitivity to thermal stress, displayed a quick stomatal closure to light, but a sluggish closure to increased vapor pressure deficit (VPD) levels. This strategy aiming both at conserving water under a high-to-low light transition and in prioritizing evaporative cooling under a low-to-high VPD transition, was mainly observed in Regina and Syrah. Moreover, cultivars with different known responses to soil moisture deficit or high air VPD (isohydric vs anisohydric) had opposite behavior under fluctuating environments, with the isohydric cultivar showing slow stomatal closure to reduced light intensity but quick temporal responses to VPD manipulation. We propose that stomatal behavior to fast environmental fluctuations can play a critical role on leaf thermoregulation and water conservation under natural field conditions in grapevine.

Photosynthesis and Transpiration in Dicotyledonous Plants. II. Expanding and Senescing Leaves of Soybean

1976 ◽  
Vol 3 (2) ◽  
pp. 257 ◽  
Author(s):  
RG Woodward ◽  
HM Rawson
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Vapour Pressure Deficit ◽  
Net Photosynthesis ◽  
Unit Leaf ◽  
Efficiency Parameter ◽  
Dicotyledonous Plants ◽  
History Of ◽  
Use Efficiency ◽  
Soybean Leaves

The history of net photosynthesis and transpiration per unit leaf area was determined for intact soybean leaves from their unfolding to senescence during flowering and pod filling on untreated (podded) and partially depodded plants growing in a glasshouse. Leaf diffusive resistances to CO2 were calculated and a water use efficiency parameter was derived (net mass of carbon dioxide fixed per unit mass of water transpired per millibar vapour pressure deficit). Net photosynthesis and transpiration behaved similarly through all stages of leaf development. A number of peaks were evident in these parameters. The first was associated with leaf expansion and occurred when the leaf reached its maximum area. The second peak coincided with flowering of the plant and later peaks occurred during pod filling. Stomatal and mesophyll resistances also exhibited similar behaviour during the life of the leaf; the possible causes of this linkage are discussed. Water use efficiency increased rapidly up to the time of full lamina expansion. Thereafter, it rose slowly or remained stable until leaf senescence approached, when the efficiency declined. Net photosynthesis and transpiration of leaves were very similar in both podded and partially depodded plants. It appears that to prevent a shortage of assimilate during flowering and pod filling, photosynthesis may be maintained or increased in some leaves and the response is not related to the number of pods available for filling. The increases in photosynthesis were correlated with both higher stomatal and mesophyll conductances. Mechanisms by which the plant may control leaf photosynthesis are discussed.

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