Photosynthesis - Science topic

The following link is also very useful RG link:

It's the coccolithaphore Emiliania huxleyi:

To optimise most plant growth it is recommended that they receive 500–1000 µmols of PAR light for every m² (PPFD). Less than this and growth rates will be low :)

There may not be direct to the point, however, I advice you read the following articles.

Thank you!

Senescence is the final stage of plant development and is characterized by a series of programmed disassembly and degenerative events. As leaves age, chloroplast degeneration is initiated, paralleled by catabolism of macromolecules, including nucleic acids, proteins and lipids. The released nutrients are exported to other developing organs, such as new buds, young leaves, flowers or seeds, which leads to increased reproductive success.

However, during photosynthesis, excess natural or artificial light can cause photo-oxidative damage to chloroplasts. It has been shown that chlorophagy, the intracellular destruction of chloroplasts, is induced by exposure to UV-B irradiation (280–315 nm) and high light. Researchers have also demonstrated that entire photo-damaged chloroplasts are transported to the plant cell vacuole for destruction.

i sorry i am not measure chlorophyll in the leaf but i measured

chlorophyll/unit photosynthesis/unit chlorophyll, in coral reef only

Light response curves can be based on either gas exchange or chlorophyll fluorescence parameters (including ETR and NPQ). In LRCs, we analyze a photosynthetic parameter relative to light intensity instead of time. This allows us to understand the dynamics of the photosynthetic apparatus relative to light intensity and understand such things as optimal light intensities, define light limiting environments, and more.

With the data of each variables, PCA can give good results

when I was a student, we were taught that it was about 1%

Please have a look at some of these PDFs...

Stomatal parts are the ones through where the photosynthesis gas for exchange passes, and defintely if the density of the stomata bodies/pores increase per given area of leaf, then there will be an increase on photosynthesis.

Despite having the same roots of origin, namely quantum superposition, coherence and entanglement are conceptually different.

Dear @Muhammad Arslan Ashraf Please check whether the attached pdf and below mentioned links could serve your purpose:

Philipp Girr Thanks, you made my day.

Also, kindly check:

Emerging approaches to measure photosynthesis from the leaf to the ecosystem:

Pollution (addition of gases into the air from human activities, such as carbon dioxide) is the main cause of climate change today.

Trees absorb some of the CO2 from the air, but people have been cutting down trees for all kinds of reasons, such as building roads, houses, etc. Therefore, unless you plant more trees and some are doing that, the CO2 builds up in the atmosphere and has the tendency to absorb heat that is being sent back into space. Instead of going to space this (outgoing) heat stays in the air and warms up the air (global warming).

Electrophoresis results are at best semi-quantitative. Starting with loading errors and gel-to-gel variability, there are many things that can go wrong. As with all dye-binding assays, colour yield depends on protein. If you have standards (in the same gel!), you'd at least get an idea what the error margins are.

If the staining is not too strong (in the linear range of the densitometer), you could scan the gels and integrate the peaks. Laser-based densitometers are better at this than simple scanners, because of a larger linear range (up to 4 AU). Even better results may come from fluorescent dyes like RuBPS and fluorescent scanners, simply because fluorescence starts from zero, whilst in absorbance you measure the small difference of two large numbers.

You could also cut out the bands, elute the bound dye and determine that photometrically.

Try BiGGR

dynamicFBA

fbar

sybilDynFBA

Have fun and Happy Research!

Pepito Payet , You may refer to this reference which may be helpful to you.The reference is in the attachment.

Please take a look at the following useful RG links.

Hi Johanna

Leaf temperature usually depends on both air temperature and vapor pressure deficit (VPD). Increasing air VPD with a good watering will lead to lower leaf temperature compared to air. It also depends on the boundary layer, but as Licor leaf chamber has a mixing fan it will blow away the boundary layer which leads to decrease in leaf temperature. If the mixing fan can be turned off, then do it first.

Then try to decrease VPD by increasing humidity of the chamber by controlling air flow rate, or of it has a humidity control, then use it.

These two methods can increase leaf temperature to a higher level. Increasing light intensity also can lead to temperature increase, but use sunlight if you can, as its wavelength temperature is significantly higher than Licor's light.

If you couldn't reach higher levels you have to give a water stress to the plant so that it decrease the transpiration rate.

All of these will finally lead to significant damage to the photosynthetic apparatus (when temperature increases above ~37 (depending on the species), so you can't hold it for long. Attached photo shows what happens to the leaf when it is kept in high temperature for too long (thermal degradation of chlorophyll), which I experienced in a branch enclosure system.

Hope it helps

Ehsan

Dear Dr Azad,

There are a few more aspects if I look at the answers given. Not all wavelengths are absorbed with the same efficiency. Green light is in this respect the least efficient. Several scientists have proposed that due to this inefficiency green light can penetrate deeper in a leaf and drive photosynthesis there. At the same time blue light is known to be absorbed by phototropins that can drive chloroplast movements and thereby affect the light absorption profile of a leaf on a minutes time scale. Red light does not do this. Phytochromes that are sensitive to red and far-red light are known to affect plant morphogenesis, etc. In other words, your question depends on the time scale considered.

Dear Namitha L H

Light, its intensity and quality, are factors that affect the concentration of different chlorophylls, especially the ratio of chlorophyll a to chlorophyll b. Plants that get abundant sunlight have less overall chlorophyll concentration and higher amounts of chlorophyll a than chlorophyll b. Plants that grow under shade, like those in densely forested areas, have a high overall chlorophyll concentration, but have more chlorophyll b than chlorophyll a.

Hybrid plants of maize, pearl millets and sorghum have more tolerance to shading stress (due to increased plant density) than those of open-pollinated varieties.

Under similar growing conditions, I did never emprically observe any difference in color intensity of leaves of hybrid and open-pollinated varieties of these crops. Therefore, dark green leaves appear to be a consequence of shading effect. I agree with J.D. Franco-Navarro and Francisca Higueras-Fredes

Best wishes, AKC

Are you looking for photosynthetic ability of periphyton microbes..??. If so , , why not to compare with rhzisosphere microbes as well...

فتوسنتزمتر

I agree with omar

Although red, green and blue quanta have different energies (different frequency), photosynthesis is driven by the number of quanta (within the visible spectrum which is approximately the PAR spectrum), not by their energy. Thus 100 uM of red quanta = 100 uM blue quanta.

CID Photosynthesis System

Dear Stefano,

On the one hand, the manufacturer should provide the PAR value emitted by the diode. On the other hand, you can visit colleague at the nearest physics / optics department and ask for an exact measurement for your instrument. You can also try to measure with an ordinary PAR meter, although the measurement will be probably burdened with a significant error. Either way, if you measure a value above 3000 everything is ok.

Plants have evolved in sunlight (~2000 PAR), so 3000 and more are likely to saturate the photosynthetic apparatus.

Many Icfre institutions also have PP systems. You may contact them for more info.

In order for cosmic rays to arrive at the surface of the earth, you have to get rid of the solar wind (which blocks cosmic rays) something not likely to happen.

Plants utilize light as a source of information in photomorphogenesis and of free energy in photosynthesis, two processes that are interrelated in that the former serves to increase the efficiency with which plants can perform the latter. Only one pigment involved in photomorphogenesis has been identified unequivocally, namely phytochrome. The thrust of this proposal is to investigate this pigment and its mode(s) of action in photosynthetically competent plants. Our long term objective is to characterize phytochrome and its functions in photosynthetically competent plants from molecular, biochemical and cellular perspectives. It is anticipated that others will continue to contribute indirectly to these efforts at the physiological level. The ultimate goal will be to develop this information from a comparative perspective in order to learn whether the different phytochromes have significantly different physicochemical properties, whether they fulfill independent functions and if so what these different functions are, and how each of the different phytochromes acts at primary molecular and cellular levels.

Dear Riya Mehrotra,

Hi, SEM is often used to view the surface characteristics and properties of organs. You must use TEM to view intracellular organelles.

Best regards,

Saeed

Thank you for the response. Yes, we are using a CO2 cartridge and it helps. We do not have a LED light source and hence this was the main reason for the variation. We are in the process of procuring the light source.

Recent findings in my lab showed that optical sensors measuring chlorophyl concentration give better results relative to indices such as NDVI. Chlorphyl concentration measurmements were comparable to fAPAR ( Fraction of Absorbed Photosynthetically Active Radiation) measurements.

Eva Maleckova

What is you actually want to do?

Because in your question it seems you want to do a lot of things which does not seem to be done as one thing.

1. How to identify differences across a big number of long protein alignments?

>> Do you mean difference within one alignment (single protein), or differences across different alignments (several proteins)?

2. You are also thinking about finding new genes, that is a bit different approach.

If you can enlist exacly what you want to do, it would be easier to answer.

Dear Sirs, if you agree with a contribution on this forum you can show your appreciation by recommending an answer or a question.

Now please stop diluting actual information with your spam answers.

No. Maybe uplland rices resistance to Pyricularia leaf blight. But on soybeans I know many geens to target. Sorry.

Dear Yoslen

Chlorophyll mainly determines the photosynthetic rate and primary productivity in plant. Chlorophyll content will be changed with the change of external environment, which could further lead to the photosynthetic capacity change. Therefore, chlorophyll content could be used as an important diagnostic indicator for plant growth study. The assessments of chlorophyll contents are based on the extraction of chlorophyll with solvents from the destructive leaf followed by spectrophotometric determination.

Li, Y., Sun, Y., Jiang, J. et al. Spectroscopic determination of leaf chlorophyll content and color for genetic selection on Sassafras tzumu. Plant Methods 15, 73 (2019).

Take a look at the article:

http://www.paper.edu.cn/scholar/showpdf/OUT2EN4IOTD0kxeQh

Pleas read the paper " Photosystem I, when excited in the chlorophyll Q y absorption band, feeds on negative entropy

Could you please look at this website:

Best regards,

Quynh Nguyen

Hy dear Habib Athar

you can use of this article and words that i sent for you.

Thank you.

Hi

In the attached article, you can get some good information on comparing photosynthesis of C3, C4 and CAM plants.

If the size of a small water system (confinement) coincides with that of a semiconductor, then the photocatalytic decomposition of water is enhanced. Quantum entanglement seems to be happening. This is the subject of our patent application.

Dear Vjacheslav Fisenko,

In our region (drylands), we found that the results of the MSAVI2 and GDVI indices are working better than the NDVI.

Good luck and best regards.

We had a similar problem. We ended up having a tiny break in the thermocouple wire which was used to measure leaf temperature. We ended up swapping it out and the problem was fixed right away. But Joshua is right, contact support, they will know exactly what to do

Hello dear ,

I think that is troposphere

Dear Samiksha,

during winter months when the water column is oxic, Fe oxide reduction only occurs in the strongly reducing sediment column. Reduced Fe(II) diffuses to the sediment-water interface where it is immediately oxidized to Fe oxide. As a result, there is no buildup of dissolved Fe in the water column during winter. In early summer the lake becomes thermally stratified. As summer progresses, oxygen is consumed by biological processes and the bottom waters become anoxic. Reductive dissolution of Fe oxide continues to occur in the sediments. Fe(II) diffuses into the anoxic bottom water and is oxidized at the oxycline forming a peak in particulate Fe in the water column. Below the oxycline, where the water is strongly reducing, dissolved Fe(II) is stabilized and its concentration increases with time. In early winter, mixing processes re-oxygenate the entire water column and Fe(II) is rapidly oxidized and precipitated.

Here is a classic work on the subject by Mortimer: https://www.jstor.org/stable/2256395?origin=crossref&seq=1#page_scan_tab_contents

After creating an account (free), you can read the article for free.

With best regards,

Johannes

With rise in temperature the productivity of C₄ plants would increase, while those of C₃ plants would decrease due to increase in rate of 'photorespiration'. Thus plants with C₄ pathway of photosynthesis would be benefited from climate change.

Some more alternatives below. I have used a custom-made solution for measuring gas exchange in shoot apex in cucumber and tomato plants. Maybe relevant! Good luck!

Besides other parameters mentioned by Kathryn, did you look at stomatal density?

Hi, here is R code for building a loop which fits a light curve model (Platt et al. 1980) to the data, extracts the coefficients into a data frame and plots the results into tiff files (one file for each fitted curve) using "phytotools" package mentioned above. This is largely based on the code examples provided by the authors of the phytotools package. One should be able to fit the other models in the package also by modifying the plot and fitting sections of the script (model equations I think are specified in phytotools documentation). This is a bit late answer but I'll upload it in any case if someone still finds this useful.

Is there a "photosynthesis gene" to be introduced? No! Consider, Vinas, the genetic complexity and the higher-order interactions of photosynthesis and also of the bacterium - then you may understand why I say it is unlikely to be achieved. But some live in hope!

In general crop rotation reduces the green house gasses, for example corn rotate with soyabean or wheat is found to be very effective in reducing GHG.

I think GC-MASS teqniqu may be useful.

Thank you very much Drs for your valuable contributions. I greatly appreciate it.

If I assume biostimulants as osmoprotectants, then effect shall be as under.These osmoprotectants such as glycine betaine,Thio urea and Salicylic Acid help to trap harmful radicles produced in plants in response to water or heat stress.These chemicals temporarily squeeze these harmful ions but this effect prevails only for short duration droughts but not useful under prolonged stress conditions.

Dear Joshua,

If you are fluent in R use (not my case unfortunately):

The Ritchie paper is really woth reading for your very initial question:

You will need to have at least some real measurements of dioxygen evolution and / or CO2 incorporation to translate rETR as true production values.

And in my own experience, @Raymond J Ritchie in Researchgate is certainly able to give you precises answers.

Hope this will help,

Christophe

I have worked with Nicotiana tabacum and Arabidopsis thaliana. As for me tobacco is more easy culture to grow and work with. But for arabidopsis there is full genome and special resourse about genes and etc https://www.arabidopsis.org/

So after some experimenting I discovered that an incubation time of at least one hour was necessary to see results. After that, fluorescence didn't show any further change. I'm leaving this answer for any who has the same question I did.

It more complex then rate perse. When algae (or any living organism) assimilate nutrients they convert simple, small molecules (here NH3 and PO4) to large complex molecules (proteins, nucleic acids etc), and finally to new cells. The absorption on the alginate is a much simpler process. Furthermore, given the above the alginate (or any other absorbing material) will reach saturation much faster as there is no conversion. Thus the rate of alginate (absorption) + micro-algae (assimilation) will be much faster.

And two small correction:

(i) Photosynthesis of micro-algae does not assimilate NO3 or PO4 directly. It provide the cells with a carbon source. The oxygen produced by the water splitting in the photosynthetic could result in oxidation of NO3 to nitrate though.

(ii) The process does no have to go "absorption in alginate --> assimilation". Depending how you make them the alginate beads can be pretty pours.

The figure roughly calculated in our paper Larkum, Ritchie and Raven 2018 is around 16. This based on how much ATP & NADPH2 is needed to fix CO2 and that PS bacteria have only one photosystem and the roundabout way PS bacteria have to make the ATP + plus NADPH2 required.

The measurements needed have largely not been seriously attempted for about 50y.

Dear

Gergino Chounna Yemele read below the attached file which title is "Mathematical modelling of natural and artificial photosynthesis "

You are welcome, Dinesh! Hope the problem will be solved soon. I know it can be very frustrating.

If you want to measure leaf area, I recommend LeafByte. It's a free and open source app for iPhones and iPads. It measures leaf area and herbivory (if you have it) much more quickly than ImageJ and related software. It also automatically saves your data for you in a spreadsheet. Did i mention that it's free?

You can download it in the app store or read more about LeafByte at the website below. You can also check out the FAQ page for ways to measure leaves non destructively and in the field.

Disclaimer-I was involved in making this app, but since its free I make no money from its use.

Look up any microalgal paper regarding light cycling or formation of lipids, especially recent ones.... If I gave you too much "proof" I might have to "get Putin" on ya....this type of stuff stays out of the "published" realm because of the crossover it has with biofuel research. Needless to say, the microalgal candidate literature (patents and journals) is full of proof and insinuation of the transition of fast photosynthesizing cells (full of chlorophyll) to senescent cells (full of TGs and lipids) in hours --I've done it in less than 8. Do a search on "lipid trigger" to get you started down the rabbit hole :)

Howdy Stancho,

First Chlrorphyll fluorescence is not a photophysical or photochemical phenomenon, but a photobiological one.

Chlorophyll fluorescence is light re-emitted by chlorophyll molecules (yes

chlorophyll!) during return from excited to non-excited states. It is used as an indicator of photosynthetic energy conversion in higher plants, algae and bacteria. Excited chlorophyll dissipates the absorbed light energy by driving photosynthesis (photochemical energy conversion), as heat in non-photochemical quenching or by emission as fluorescence radiation. As these processes are complementary processes, the analysis of chlorophyll fluorescence is an important tool in plant research with a wide spectra of applications.

The Kautsky effect

Upon illumination of a dark-adapted leaf, there is a rapid rise in fluorescence from Photosystem II (PSII), followed by a slow decline. First observed by Kautsky et al., 1960, this is called the Kautsky Effect. This variable rise in chlorophyll fluorescence rise is due to photosystem II. Fluorescence from photosystem I is not variable, but constant.

The increase in fluorescence is due to PSII reaction centers being in a "closed" or chemically reduced state. Reaction centers are "closed" when unable to accept further electrons. This occurs when electron acceptors downstream of PSII have not yet passed their electrons to a subsequent electron carrier, so are unable to accept another electron. Closed reaction centres reduce the overall photochemical efficiency, and so increases the level of fluorescence. Transferring a leaf from dark into light increases the proportion of closed PSII reaction centres, so fluorescence levels increase for 1–2 seconds. Subsequently, fluorescence decreases over a few minutes. This is due to; 1. more "photochemical quenching" in which electrons are transported away from PSII due to enzymes involved in carbon fixation; and 2. more "non-photochemical quenching" in which more energy is converted to heat.

Chlorophyll fluorescence appears to be a measure of photosynthesis, but this is an over-simplification. Fluorescence can measure the efficiency of PSII photochemistry, which can be used to estimate the rate of linear electron transport by multiplying with light intensity. However, researchers generally mean carbon fixation when they refer to photosynthesis. Electron transport and CO2 fixation correlate well, but may not correlate in the field due to processes such as photorespiration, nitrogen metabolism and the Mehler reaction.

A powerful research technique is to simultaneously measure chlorophyll fluorescence and gas exchange to obtain a full picture of the response of plants to their environment. One technique is to simultaneously measure CO2 fixation and PSII photochemistry at different light intensities, in non-photorespiratory conditions. A plot of CO2 fixation and PSII photochemistry indicates the electron requirement per molecule CO2 fixed. From this estimation, the extent of photorespiration may be estimated. This has been used to explore the significance of photorespiration as a photoprotective mechanism during drought.

Fluorescence analysis can also be applied to understanding the effects of low and high temperatures.

Chlorophyll fluorescence can measure most types of plant stress. Chlorophyll fluorescence can be used as a proxy of plant stress because environmental stresses, e.g. extremes of temperature, light and water availability, can reduce the ability of a plant to metabolise normally. This can mean an imbalance between the absorption of light energy by chlorophyll and the use of energy in photosynthesis.

A portable multiparametric fluorometer using the ratio between chlorophyll and flavonols can be applied to detect nitrogen deficiency in plants Because of the link between chlorophyll content and nitrogen content in leaves, chlorophyll fluorometers can be used to detect nitrogen deficiency in plants, by several methods.

Based on several years of research and experimentation, polyphenols can be assigned as indicators of the nitrogen status of a plant. For instance, when a plant is under optimal conditions, it favours its primary metabolism and synthesises the proteins (nitrogen molecules) containing chlorophyll, and few flavonols (carbon-based secondary compounds). On the other hand, in case of lack of nitrogen, we will observe an increased production of flavonols by the plant.

The NBI (Nitrogen Balance Index), allows the assessment of nitrogen conditions of a plant by calculating the ratio between Chlorophyll and Flavonols (related to Nitrogen/Carbon allocation) .

Hence Stancho,

I hope this short summary elucidates soma aspects of the photobiology of plant chlorophyll fluorescence. A lot more information is available. For example models to simulate plant fluorescence. An interesting one can be found at:

Success with your studies,

Frank

In a optimum condition for growth, I sprayed my plant with cytokinin, the levels of antioxidant enzymes (POD, SOD, catalase) in these plant was higher than control (foliar with distilled water). why?? It's not a results due to reduce free radicals?

I think chlorophyll fluorescence can capture the emergent properties of the photosynthesis system and is very fast, so it should be a good tool for screening photosynthesis mutants. Also, a thermal camera can give information on relative leaf cooling, which rapidly captures the emergent properties of stomatal openness and transpiration, and they give information about the stomatal limitations to photosynthesis, which should be coordinated with carboxylation capacity. Traditional gas exchange approaches (a-ci curves, light response curves), give more detailed information, but are time-consuming and not practical for screening large numbers of mutants.

in the night plants cannot do photosynthesis as for this sunlight is required. Plants then do respiration, which consumes oxygen. then they also produce co2 (which they also do during day, but only during day they have photosynthesis.

It depends on what you mean by photosynthesis in this context. Do you mean the creation of more energetic molecules from less energetic ones and using them to make products like polymers and such like? Or do you you simply mean extracting energy from the solar input and converting it to something useful like electricity? We can do the second very well now; but the first probably won't scale up because in the end you are simply trying to redesign biological systems to make them "more efficient". But now you need to define what you mean by efficient and examine the ecological price of obtaining such an improvement. Since the input energy - sunlight - is free, it isn't clear why you want to do better than the existing biological mechanisms; any replacement would have to scale up to the same level of production and that will be an environmental nightmare as you may find the two systems are not compatible and you end up destroying the very ecosphere you set out trying to save.

C4 plants are more efficient in CO2 fixation due to the absence of photorespiration .. CAM plants photosynthes is usually take place in desert and succulent plants that close their stomata during day time to minimize lost of water .