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Photosynthesis systems are
electronic
Electronic may refer to:
*Electronics, the science of how to control electric energy in semiconductor
* ''Electronics'' (magazine), a defunct American trade journal
*Electronic storage, the storage of data using an electronic device
*Electronic co ...
scientific
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
instruments designed for non-destructive measurement of
photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...
rates in the field. Photosynthesis systems are commonly used in
agronomic
Agricultural economics is an applied field of economics concerned with the application of economic theory in optimizing the production and distribution of food and fiber products.
Agricultural economics began as a branch of economics that specif ...
and
environmental
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
research, as well as studies of the global
carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...
.
How photosynthesis systems function
Photosynthesis systems function by measuring gas exchange of
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
. Atmospheric
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
is taken up by leaves in the process of
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
, where is used to generate sugars in a molecular pathway known as the
Calvin cycle
The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into ...
. This draw-down of induces more atmospheric to diffuse through
stomata
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...
into the air spaces of the leaf. While stoma are open, water vapor can easily diffuse out of plant tissues, a process known as
transpiration
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth a ...
. It is this exchange of and water vapor that is measured as a proxy of photosynthetic rate.
The basic components of a photosynthetic system are the leaf chamber,
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
gas analyzer (IRGA), batteries and a console with keyboard, display and memory. Modern 'open system' photosynthesis systems also incorporate miniature disposable compressed gas cylinder and gas supply pipes. This is because external air has natural fluctuations in and water vapor content, which can introduce measurement noise.
[ Modern 'open system' photosynthesis systems remove the and water vapour by passage over soda lime and Drierite, then add at a controlled rate to give a stable concentration.][ Some systems are also equipped with temperature control and a removable light unit, so the effect of these environmental variables can also be measured.
The leaf to be analysed is placed in the leaf chamber. The concentrations is measured by the infrared gas analyzer.][ The IRGA shines infrared light through a gas sample onto a detector. in the sample absorbs energy, so the reduction in the level of energy that reaches the detector indicates the concentration. Modern IRGAs take account of the fact that absorbs energy at similar wavelengths as .][ Modern IRGAs may either dry the gas sample to a constant water content or incorporate both a and a water vapour IRGA to assess the difference in and water vapour concentrations in air between the chamber entrance and outlet.]
The Liquid Crystal Display
A liquid-crystal display (LCD) is a flat panel display, flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liqui ...
on the console displays measured and calculated data. The console may have a PC card slot. The stored data can be viewed on the LCD display, or sent to a PC. Some photosynthesis systems allow communication over the internet using standard internet communication protocols.
Modern photosynthetic systems may also be designed to measure leaf temperature, chamber air temperature, PAR (photosynthetically active radiation Photosynthetically active radiation (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more o ...
), and atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
. These systems may calculate water use efficiency
Water-use efficiency (WUE) refers to the ratio of water used in plant metabolism to water lost by the plant through transpiration. Two types of water-use efficiency are referred to most frequently:
*photosynthetic water-use efficiency (also call ...
(A/E), stomatal conductance Stomatal conductance, usually measured in mmol m−2 s−1 by a porometer, estimates the rate of gas exchange (i.e., carbon dioxide uptake) and transpiration (i.e., water loss as water vapor) through the leaf stomata as determined by the degree of ...
(gs), intrinsic water use efficiency
Water-use efficiency (WUE) refers to the ratio of water used in plant metabolism to water lost by the plant through transpiration. Two types of water-use efficiency are referred to most frequently:
*photosynthetic water-use efficiency (also call ...
(A/gs), and sub-stomatal concentration (Ci).[ Chamber and leaf temperatures are measured with a thermistor sensor. Some systems are also designed to control environmental conditions.
A simple and general equation for Photosynthesis is:
+ + (Light Energy)→ C6H12O6+O2
]
'Open' systems or 'closed' systems
There are two distinct types of photosynthetic system; ‘open’ or ‘closed’.[ This distinction refers to whether or not the atmosphere of the leaf-enclosing chamber is renewed during the measurement.]
In an ‘open system’, air is continuously passed through the leaf chamber to maintain in the leaf chamber at a steady concentration.[ The leaf to be analysed is placed in the leaf chamber. The main console supplies the chamber with air at a known rate with a known concentration of and .] The air is directed over the leaf, then the and concentration of air leaving the chamber is determined.[ The out going air will have a lower concentration and a higher concentration than the air entering the chamber. The rate of uptake is used to assess the rate of photosynthetic ]carbon assimilation
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up ...
, while the rate of water loss is used to assess the rate of transpiration. Since intake and release both occur through the stomata, high rates of uptake are expected to coincide with high rates of transpiration. High rates of uptake and loss indicates high stomatal conductance.
Because the atmosphere is renewed, 'open' systems are not seriously affected by outward gas leakage and adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a f ...
or absorption
Absorption may refer to:
Chemistry and biology
* Absorption (biology), digestion
**Absorption (small intestine)
*Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials
*Absorption (skin), a route by which ...
by the materials of the system.[
In contrast, in a ‘closed system’, the same atmosphere is continuously measured over a period of time to establish rates of change in the parameters.] The concentration in the chamber is decreased, while the concentration increases. This is less tolerant to leakage and material ad/absorption.
Calculating photosynthetic rate and related parameters
Calculations used in 'open system' systems;
For CO2 to diffuse
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
into the leaf, stomata must be open, which permits the outward diffusion of water vapour. Therefore, the conductance of stomata influences both photosynthetic rate (A) and transpiration (E), and the usefulness of measuring A is enhanced by the simultaneous measurement of E. The internal concentration (Ci) is also quantified, since Ci represents an indicator of the availability of the primary substrate (CO2) for A.[
A ]carbon assimilation
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up ...
is determined by measuring the rate at which the leaf assimilates .[ The change in is calculated as flowing into leaf chamber, in μ mol mol−1 , minus flowing out from leaf chamber, in μmol mol−1. The photosynthetic rate (Rate of exchange in the leaf chamber) is the difference in concentration through chamber, adjusted for the molar flow of air per m2 of leaf area, mol m−2 s−1.
The change in H2O ]vapour pressure
Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases ...
is water vapour pressure out of leaf chamber, in mbar, minus the water vapour pressure into leaf chamber, in mbar. Transpiration rate is differential water vapour concentration, mbar, multiplied by the flow of air into leaf chamber per square meter of leaf area, mol s−1 m−2, divided by atmospheric pressure, in mBar.
Calculations used in 'closed system' systems;
A leaf is placed in the leaf-chamber, with a known area of leaf enclosed. Once the chamber is closed, carbon dioxide concentration gradually declines. When the concentration decreases past a certain point a timer is started, and is stopped as the concentration passes at a second point. The difference between these concentrations gives the change in carbon dioxide in ppm. Net photosynthetic rate in micro grams carbon dioxide s−1 is given by;
(V • p • 0.5 • FSD • 99.7) / t
where V = the chamber volume in liters, p = the density of carbon dioxide in mg cm−3, FSD = the carbon dioxide concentration in ppm corresponding to the change in carbon dioxide in the chamber, t = the time in seconds for the concentration to decrease by the set amount. Net photosynthesis per unit leaf area is derived by dividing net photosynthetic rate by the leaf area enclosed by the chamber.
Applications
Since photosynthesis, transpiration and stomatal conductance are an integral part of basic plant physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
, estimates of these parameters can be used to investigate numerous aspects of plant biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
. The plant-scientific community has generally accepted photosynthetic systems as reliable and accurate tools to assist research. There are numerous peer-reviewed
Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work (peers). It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer review ...
articles in scientific journals which have used a photosynthetic system. To illustrate the utility and diversity of applications of photosynthetic systems, below you will find brief descriptions of research using photosynthetic systems;
* Researchers from the Technion - Israel Institute of Technology and a number of US institutions studied the combined effects of drought and heat stress on ''Arabidopsis thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land.
A winter a ...
''. Their research suggests that the combined effects of heat and drought stress cause sucrose to serve as the major osmoprotectant.
* Plant physiologists from The University of Putra Malaysia and The University of Edinburgh
The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 15 ...
investigated the relative effects of tree age and tree size on the physiological attributes of two broadleaf species. A photosynthetic system was used to measure photosynthetic rate per unit of leaf mass.
* Researchers at University of California-Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant univ ...
found that water loss from leaves in ''Sequoia sempervirens'' is ameliorated by heavy fog in the Western US. Their research suggests that fog may help the leaves retain water and enable the trees to fix more carbon during active growth periods.
* The effect of CO2 enrichment on the photosynthetic behavior of an endangered medicinal herb was investigated by this team at Garhwal University, India. Photosynthetic rate (A) was stimulated during the first 30 days, then significantly decreased. Transpiration
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth a ...
rate (E) decreased significantly throughout the CO2 enrichment, whereas stomatal conductance Stomatal conductance, usually measured in mmol m−2 s−1 by a porometer, estimates the rate of gas exchange (i.e., carbon dioxide uptake) and transpiration (i.e., water loss as water vapor) through the leaf stomata as determined by the degree of ...
(gs) significantly reduced initially. Overall, it was concluded that the medicinally important part of this plant showed increased growth.
* Researchers at the University of Trás-os-Montes and Alto Douro
The University of Trás-os-Montes and Alto Douro (UTAD; Portuguese: ''Universidade de Trás-os-Montes e Alto Douro'') is a public university located in the north-eastern city of Vila Real, Portugal.
It became a public university in 1986, althoug ...
, Portugal grew Grapevines in outside plots and in Open-Top Chambers which elevated the level of CO2. A photosynthetic system was used to measure CO2 assimilation rate (A), stomatal conductance (gs), transpiration rate (E), and internal CO2 concentration/ambient CO2 ratio (Ci/Ca). The environmental conditions inside the chambers caused a significant reduction in yield.
* A study of Nickel bioremediation
Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi, and plants), living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluent ...
involving poplar (''Populas nigra''), conducted by researchers at the Bulgarian Academy of Sciences and the National Research Institute of Italy (Consiglio Nazionale delle Ricerche
The National Research Council (Italian: ''Consiglio Nazionale delle Ricerche, CNR'') is the largest research council in Italy. As a public organisation, its remit is to support scientific and technological research. Its headquarters are in Rome. ...
), found that Ni-induced stress reduced photosynthesis rates, and that this effect was dependent upon leaf Ni content. In mature leaves, Ni stress led to emission of cis-β-ocimene, whereas in developing leaves, it led to enhanced isoprene
Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals ...
emissions.
* Plant physiologists in Beijing measured photosynthetic rate, transpiration rate and stomatal conductance in plants which accumulate metal and those that do not accumulate metal. Seedlings were grown in the presence of 200 or 400 μM CdCl2. This was used to elucidate the role of antioxidative
Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. This can lead to polymerization and other chain reactions. They are frequently added to indust ...
enzyme in the adaptive responses of metal-accumulators and non-accumulators to Cadmium stress.
* In a study of drought resistance and salt tolerance of a rice variety, researchers at the National Center of Plant Gene Research and the Huazhong Agricultural University in Wuhan, China found that a transgenic rice variety showed greater drought resistance than a conventional variety. Over expression of the stress response gene SNAC1 led to reduced water loss, but no significant change in photosynthetic rate.
* This Canadian team examined the dynamic responses of Stomatal conductance (gs) net photosynthesis (A) to a progressive drought in nine poplar clones with contrasting drought tolerance
Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions'','' surviving with protection mechanisms such as desiccation tolerance, detox ...
. gs and A were measured using a photosynthetic system. Plants were either well-watered or drought preconditioned.
* Researchers at Banaras Hindu University
Banaras Hindu University (BHU) IAST: kāśī hindū viśvavidyālaya IPA: /kaːʃiː hɪnd̪uː ʋɪʃwəʋid̪jaːləj/), is a collegiate, central, and research university located in Varanasi, Uttar Pradesh, India, and founded in 1916 ...
, India, investigated the potential of sewage sludge to be used in agriculture as an alternative disposal technique. Agricultural soil growing rice had sewage sludge added at different rates. Rates of photosynthesis and stomatal conductance of the rice were measured to examine the biochemical and physiological responses of sewage addition.
* Researchers from Lancaster University
Lancaster University (legally The University of Lancaster) is a public university, public research university in Lancaster, Lancashire, Lancaster, Lancashire, England. The university was established in 1964 by royal charter, as one of several pla ...
, The University of Liverpool
, mottoeng = These days of peace foster learning
, established = 1881 – University College Liverpool1884 – affiliated to the federal Victoria Universityhttp://www.legislation.gov.uk/ukla/2004/4 University of Manchester Act 200 ...
, and The University of Essex
The University of Essex is a public university, public research university in Essex, England. Established by royal charter in 1965, Essex is one of the original plate glass university, plate glass universities. Essex's shield consists of the an ...
, UK, measured isoprene emission rates from an oil palm tree. Samples were collected using a photosynthetic system that controlled PAR and leaf temperature (1000 μmol m−2 s−1; 30 °C). It had thought that PAR and temperature are the main controls of isoprene emission from the biosphere. This research showed that isoprene emissions from oil palm tree are under strong circadian control.
* The ecophysiological diversity and the breeding potential of wild coffee populations in Ethiopia was evaluated as a thesis submitted to The Rheinischen Friedrich-Wilhelms-University of Bonn, Germany. Complementary field and garden studies of populations native to a range of climatic conditions were examined. Plant ecophysiological behavior was assessed by a number of system parameters, including gas exchange, which was measured using a photosynthetic system.
* A collaborative project between researchers at the University of Cambridge
, mottoeng = Literal: From here, light and sacred draughts.
Non literal: From this place, we gain enlightenment and precious knowledge.
, established =
, other_name = The Chancellor, Masters and Schola ...
, UK, the Australian Research Council Center of Excellence, and the Australian National University
The Australian National University (ANU) is a public research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies and ...
resulted in validation of a model that describes carbon isotope discrimination for crassulacean acid metabolism using ''Kalanchoe daigremontiana''.
* Instruments of this type can also be used as a standard for plant stress measurement
Plant stress measurement is the quantification of environmental effects on plant health. When plants are subjected to less than ideal growing conditions, they are considered to be under stress. Stress factors can affect growth, survival and crop y ...
. Difficult to measure types of plant stress such as Cold stress, and water stress can be measured with this type of instrumentation.
References
External links
* http://www.ipipotash.org/udocs/CO2_Gas_exchange_parasystems_paper.pdf
* {{cite journal , pmc=425915 , pmid=16661870 , volume=68 , title=Carbon Dioxide Exchange in Lichens : RELATIONSHIP BETWEEN NET PHOTOSYNTHETIC RATE AND CO(2) CONCENTRATION , year=1981 , journal=Plant Physiol. , pages=199–201 , last1 = Green , first1 = TG , last2 = Snelgar , first2 = WP , issue=1 , doi=10.1104/pp.68.1.199
Plant physiology