Plant Environmental Stress Physiology - Science topic

I just discovered this question and after seeing the answers, I would like to add to the list of plants with naturally-occurring red-colored roots. My experience with growing Philodendron "Painted Lady" (cultivar of Philodendron erubescens) has shown it to be one of the plants whose majority of the root surface naturally has a reddish hue. More specifically, I have observed that the older roots transition to a reddish-brown tone over time, while the newer roots retain a brighter color, with their tips being the most vivid red part. (of course this does not apply to trichomes as they appear white).

Not sure if there is a genetic relationship here since the stem of this cultivar is red as well, but that phenomenon is not as unusual as the root color trait.

This phenomenon is possible for some species but for some others it is not suitable for their growth.

According your question you may adjust concentration of all nutrients of the Hoagland solution in order to check potassium control. You may also take care about the varieties you are using for your work.

Since according to acid growth considerations apoplastic pH is an important factor in elongation growth, we suggest that this pH increase is a main cause for reduced leaf growth under salt stress conditions.

Dear @Navindra Boodia You can access following links; hope, these would be useful to you:

Dear Somayeh Abdirad ,

The following article is related to your question.

Agreed with Sajid Khan

Dear M. Manokari thanks for posting this interesting technical question on RG. As an inorganic chemists I'm absolutely no specialist in this field. However, I noticed that this seems to be a relatively common phenomenon. There are a number of closely related questions and discussions on the internet. For example, please have a look at the following potentially useful links:

Apparently such white spots on Aloe vera can be natural or caused by fungi. I hope this helps. Good luck with your work!

Dear Sir,

See next link:

Good luck,

Leaf and petiole analysis is an established tool. Protocol for perennial crops have been standardized for nutrient analysis.

ACC deaminase activity on the sterile minimal DF (Dworkin and Foster) salts media (DF salts per liter: 4.0 g KH2PO4, 6.0 g Na2HPO4, 0.2 g MgSO4.7H2O, 2.0 g glucose, 2.0 g gluconic acid and 2.0 g citric acid with trace elements: 1 mg FeSO4.7H2O, 10 mg H3BO3, 11.19 mg MnSO4.H2O, 124.6 mg ZnSO4.7H2O, 78.22 mg CuSO4.5H2O, 10 mg MoO3, pH 7.2) amended with 3 mM ACC instead of (NH4)2SO4 as sole nitrogen source (Dworkin and Foster, 1958; Penrose and Glick, 2003). The inoculated plates were incubated at 28°C for 3 days and growth was monitored on a daily basis. Colonies growing on the plates were taken as ACC deaminase producers. Samar Salama Natasha Tilikj

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/

Dear Renata

I think the presence of chlorophyll in any plant due to the interaction of environmental conditions with genetic makeup of any plant

The tall plant protects the short plant from high temperatures through intercropping which indicates the formation of plant pigments will be affected under these conditions

Chitosan is a safe and biodegradable plant stimulant. It is able to stimulate the enzyme production related to defensive responses in plants, such as catalase, peroxidase chitinases, glucanases and phenylalanine ammonia lyase (PAL) etc. It triggers the accumulation of different signaling molecules like Hydrogen peroxide, Nitric oxide (NO) which increase the activity of different defensive response by increasing the activity of defensive gene and increase the synthesis of plant secondary metabolites when plants are suffer from environmental stresses. Chitosan also increase the content of Jasmonic acid and ABA in plant resulting closure of the plant’s stomata and reduced transpiration during drought condition.

Dear Ibrahim Abd El Khalek Abd El Mola,

Please also have a look at these useful ResearchGate links.

...

Good luck!

You need to have first hand information on stagewise water requirement or alternatively having some baseline information on daily evaporation rate , you can schedule two three option to test with .Please remember , testing these genotypes against terminal drought is most important .

I would like to suggest you to use AGD-R and Eval_LxT software developed by CIMMYT.

both are a user friendly software which not need syntax (script) but you need to install R-software on your PC.

The next Xylem International meeting will most likely be organized by the University of Padova in Italy i September/October 2019. We are finalizing the organisation right now and I will let you know when I know more.

And yes, Cavitation will be "la part du lion" in this meeting!

Hervé

Dear Phil,

You can get a sense of how soil temperature varies with depth when exposed to fire by using the software FOFEM, which is physically based and produces graphs of temperature vs depth. Curious that a few years back I did simulations for Cistus ladanifer.

Thank you for all the answers and I appreciate your time and wisdom, I am still taking some academic subjects, such as plant stress physiology, water relations in plants and vegetable physiology, this semester which will enhance my understanding towards my planned thesis.

By the way, my proposed crop would be onion (my province is the highest producer) which is a highly susceptible to flood/high moisture especially when "unexpected typhoon" landed during planting season which is a result of climate change in the Philippines. My ideal work plan would be most likely to combat the harmful effects of flood stress such as use of antioxidants/chemicals that may alleviate the stress on the plant. Also, the level of flood stress could be variable depending on the water content/submergence in the soil as well as the amount of time of flood stress condition. Most likely it would be a pot experiment first under greenhouse condition and if the outcome is favorable it may undergo field trial.

These are some of my reading articles:

Waterlogging tolerance of Welsh onion (Allium fistulosum L.) enhanced by exogenous spermidine and spermine

Use of spermidine reduced the oxidative damage in onion seedlings under salinity by modulating antioxidants

It may be a challenged for this crop, also it still a long run (about 5 months) for me to write my proposed thesis, I will still gather more information, related researches and discussion with my adviser. I am gladly to contact all of you to seek for an advice.

you can aplication for droughts a kaolinite.

Thanks for information.

Sir how pinching increase flower size?

Dendrochronological analysis of urban trees: climatic response and impact of drought on frequently used tree species,Trees, August 2014, Volume 28, Issue 4, pp 1079–1093

Abstract : Trees in urban environments are exposed to heat stress, low air humidity and soil drought. The increasing temperatures and the more frequent heat and drought events will intensify the stress level of urban trees. We applied a dendrochronological approach to evaluate the species-specific suitability under increasing risk of drought of five tree species at highly sealed urban sites in the city of Dresden (Germany). Climate-growth correlation analyses show that temperatures and water availability from April to July in the current year and in summer and autumn of the previous year are the main determining factors for radial growth. However, distinct species-specific differences were found in the response to temperature, precipitation and the self-calibrated Palmer Drought Severity Index. During the study period, the influence of temperature and drought on radial growth during summer months increases for Acer platanoides and Acer pseudoplatanus, whereas no changes occurred for Quercus petraea, Quercus rubra, and P. × hispanica. Pointer year analysis and superposed epoch analyses revealed a species-specific response to extreme climatic events. While for A. platanoides and A. pseudoplatanus a higher number of negative pointer years and significant growth declines in drought years were found, Q. petraea and Q. rubra showed more frequent positive pointer years but no significant growth reductions during drought. Based on these response patterns we classified the studied tree species according to their suitability and drought tolerance for urban sites.

Some PDFs enclosed for reference...

Here are more recent article that explain the details:  

1. Involvement of Ethylene Biosynthesis and Signalling in the Transition from Male to Female Flowering in the Monoecious Cucurbita pepo. J Plant Growth Regul. December 2013, Volume 32, Issue 4, pp 789–798. DOI 10.1007/s00344-013-9344-6

2. Transcriptomic Analysis Implies That GA Regulates Sex Expression via Ethylene-Dependent and Ethylene-Independent Pathways in Cucumber (Cucumis sativus L.)

I hope you will find this information useful

Seedling emergence response to temperature in safflower: measurements and modeling (Torabi et al., 2015)

I think  , the bigger issue is , how to evaluate the response of drought stress , considering the fact that untimely rains would neutralise the magnitude of plant response to acquired  quantum of drought stress. Or alternatively , when a plant  on the way to reach critical drought stress and rain comes , will surely take away the stimulus of drought stress form the plant..?

Interesting discussion...

The interaction between calcium and phosphate is complex because these ions both support and counteract each other. The supporting effect is due to a simultaneous uptake and translocation of calcium and phosphate. The counteracting effect is caused by precipitation of less soluble calcium phosphates at the vicinity of nutrient-absorbing roots.

At high activity ratios between potassium and calcium the risk of calcium deficiency is obvious. The capability of plants to absorb calcium ions is then increased by application of soluble phosphate fertilizers. In a field experiment, application of potassium chloride decreased the uptake of phosphorus and crop yield. Application of ammonium phosphate increased the content of water-soluble phosphate in a soil extract and the early uptake of phosphorus and calcium. Application of ordinary superphosphate had less effect than ammonium phosphate on the solubility of phosphate in the soil, whereas the calcium ion activity and crop yield increased considerably.

Excess input of potassium is usual on farms with a high animal stocking rate and on vegetable farms where potash fertilizers have been used in excessive amounts for years. Decreased uptake and utilization of magnesium and calcium in plants cause quality problems for products. It is suggested to limit excessive fertilization of potassium and to control the balances between nutrients by testing the activity ratios in the soil extracts. Source : Journal Acta Agriculturae Scandinavica, Section B — Soil & Plant Science  Volume 43, 1993 - Issue 1

Another PDF enclosed fro further reading 

Hello,

This topic comes up very frequently.  

I worked on this as PhD student 50 years ago!

At the risk of repetition and being egotistical you might like to read :

Lawlor DW (1969)  Plant Growth in Polyethylene Glycol Solutions in Relation to the Osmotic Potential of the Root Medium and the Leaf Water Balance  J. Exp. Bot. 20 (4): 895

Lawlor Dw (1970) ABSORPTION OF POLYETHYLENE GLYCOLS BY PLANTS AND THEIR EFFECTS ON PLANT GROWTH.  New Phytologist 

DOI: 10.1111/j.1469-8137.1970.tb02446.x

Both are available on Research Gate

There are many aspects you need to consider in using PEG to get effective results

Regards

David Lawlor

If you mean very yellow, check the stress levels of drought and salt on alfaalfa.

Drought you apply might be so severe that it kills or worsens much compared to salt.

Best.

Nusret

Wetting the leaves and subjecting them to sub-zero temperatures will enhance damages to cell membranes and electrolyte leakage. So, you can first wash the leaf  in order to remove dust or anything else which may increase electrical conductivity.  Then smoothly remove the remaining water from leaf surface and place the leaf or leaf discs of uniform size in the container without wetting.

I think more details are needed, but I could think of some reasons, if the cuttings where planted in the same substrate, the salt could have accumulated in it. If the cuttings where In vitro then maybe they could have phenolized through the cut tissue.

Please send more information and if possible pictures.

Yes that's how I would start. First use NCBI Taxonomy browser with your species name and targeted gene to find which closely related species have available sequences for that gene. Once done align all the sequences (10-15 should do). Then try to design degenerate primers, it usually works, but go well below the calculated Tm when you perform the PCR.

I believe the key to the answer is in the evolutionary or physiological significance of the metabolites. Were they produced as a response to stress or as a result of the promotion of certain processes that are influenced by changes in the environment such as light intensity, quality and duration; temperature, pressure, [CO2] etc? If these metabolites are a response to stress conditions prevalent at high altitudes, reversion to low altitudes may reduce the concentrations produced. In the same vein plants from high altitudes may produce less at low altitudes. However this still needs to be validated by appropriate experimentation

Hello Yasser

Replication is often a problem, because of the time and cost involved as pointed out by Kazem but correct replication is essential to enable proper evaluation of the problem being considered and application of correct statistics.  So it is necessary to always have replication irrespective of time etc: if is better to do an experiment properly than to do it incorrectly and get a results which is basically of no value. A replicate is sometimes called a "repeat" but to  repeat means to do again - after a time - whereas a replicate' is don with the other replicates at the same time.

The number of replicates should ideally be determined by doing an experiment to test the methods. Note, earlier comments about using fresh plant material or dry -  drying may cause proline to accumulate in the material, so fresh is probably better but be careful to  analyse before the tissue loses water, or freeze quickly and analyse later. You could or should test this before starting the study. 

First test the analysis on a standard of proline (generally purchased from a reputable supplier) by  adding different amounts to a uniform sample of the material you will be analysing (include a blank to measure the amount of proline in the original material). Repeat the measurement several times  for each concentration. This will tell you a lot about the analysis methods, quantities etc and if you have sufficient replicates for the analysis to get an acceptable statistical error, to give say a standard error of the man of 1, 5 or 10%. 

For the experiment:  Say you want to test how many replicates are required to analyse proline in plant material grown  in field trials with a wet and dry treatment. Each treatment will have 3  replicated plots, watered independently (ideally): 3 is a number often used as it is the minimum for statistical purposes. From each plot take three plants at random.  The amount of proline in each plant from each plot is measured using the required number of replicates of the proline analysis (let's say 3).   There are 2 treatments (the effect on the plant is to be examined) X 3 replicate plots (treatment replicates) X 3 plants (`biological replicates')  X 3 `analytical replicates' that gives = 54 samples to analyse. This is quite a lot of work! But it is a fully replicated experiment which takes into account random errors in the treatment of the plants (differences between plots and the treatment), variations between plants within plots and errors in the analysis between each plant.  The data can be statistically analysed with confidence and the result are meaningful, 

It is possible to decrease the amount of work by combining, say, the three plants from 1 plot together to give a bulked sample and then using 2 replicates of the plant material from the plot. This gives 2 X 3 X 2 x 3 = 36 samples. If the analysis is very good with very small errors then replication of the analysis might be decreased to 2 so giving 24 samples, which is not so large! But decreasing replication means the experiment is not as statistically `good'.

This all sounds very complex and demanding . The reason for it is that experience over many years shows that  combining experimental  methods with statistics  give the best results and thus provide a firm basis for understanding. I hope I have not put you off but encouraged you to apply the scientific approach.

Regards

If you want to develop full potential Ecophysiology lab you need following infrastucture

1. Water potential measurement system (Wescor is good)

2. Portable photosynthesis system (Li Cor 6400xt is good)

3. Fluorescence monitoring system (Walz machines are Good)

4. Conductivity bridge for assessing membrane damage etc.

5. If you want assess oxidative damage in plants you need a spectrophotometer

6. Portable leaf area meter etc.

7. LAI measurement systems

Good luck for having adequate funds  because all these equipments are bit costly.

Dr. Annamalainathan

Hello,

My paper, 'Productivity-decomposition dynamics of Typha orientalis at Kaitoke Swamp, Great Barrier Island, New Zealand', describes some water chemistry testing.

I hope that it is useful.

Regards,

Andrew :-)  

if you keep it more time the plant will die . in nature , the stress conditions usually short period . if the plant can adopt after long time so there is no benefit for the study

Ice nucleus first build up in the intercellular  spaces where pure water is occurred with increasingly reduction of temperature ice attract water from cytoplasm, increasing the ice crystal until it extended to cell wall destructing them. Finally, owing to water attraction,  the hydrophillic parts of the cellular membrane is affected and thus cellular membrane deformed, enzymes fractionated in to cytoplasm  

Dear Mehdi and Juan Antonio,

Yes, indeed a 1 m bar-type quantum sensor would be the best instrument for measuring PAR in a canopy. Using a small sensor is not impossible, but would require many replicate measurements (in the order of hundreds per location).

What is usually the difference between expensive and cheap quantum sensors?

1) Spectral response: Li-Cor is best with this, you can use Li-Cor sensors under different white light sources with the same calibration and relatively small systematic errors: say less than 10% or so. Cheaper sensors are not really true PAR sensors, they are calibrated as PAR sensors but tend to need recalibration for each different light source. Even some of Apogee's sensors suffer from this problem http://www.apogeeinstruments.co.uk/quantum/ and while Apogee is outspoken about it, other cheap sensors for which makers do not publish the spectral response may be even worse in this respect. For the Spectrum Technology's sensors you can find in their website a manual where the spectral response is plotted, if you compare this curve to that for the "original Apogee" sensor and the true PAR response one can see that the spectral response of this cheaper sensor is really not at all like PAR. However, if the spectral quality of the light is known and the calibration has been done for this same spectral quality, measurements can be almost as good, but you need to take into account that the calibration is strongly light-source dependent. In any case I would not buy any light sensor unless the manufacturer publishes the sensor's spectral response curve as part of the specifications.

2) Cosine correction. Usually only the most expensive sensors get close to the theoretical response as the angle of incidence of light changes. This is especially important, for a horizontal sensor, when solar angles are low, or in any other situation when light is received at a low angle, possibly under a bush in a discontinuous canopy. Again I would not buy any sensor unless the manufacturer specifies the cosine-correction errors.

Other considerations:

a) Buy a sensor that is attached to the meter with a long cable, otherwise you will be unable to avoid your own shade affecting the measurements. Even with a long (2-3 metres) cable make sure to be as low as possible (not standing) and blocking as little of the light as possible. Be also aware that if wearing white or light-coloured clothes you can also increase the readings by acting as a reflector if suitably positioned. The best way to work out what is safe is to rehearse and experiment.

b) For measurements to be reliable and comparable, the sensor needs to be levelled. Li-Cor, Apogee, and most other makers of sensors for field use sell levelling bases with a spirit level. These bases do also play another role: they are heavy enough to keep the sensor where you want while you move some distance away from it to take the readings without causing shading.

c) Temperature stability should be o.k. for most quantum sensors. Weather/water proofing will vary.

Additional thoughts:

1) With care, if you can borrow one of the expensive sensors or a good spectrometer you can calibrate a cheap or even a home-made sensor. This may make sense if you need many sensors.

2) Any sensor should be recalibrated regularly. Calibration of cheap sensors may drift more, requiring more frequent recalibration under continuous field use. Li-Cor sensors are very stable in my experience: recommendation is to recalibrate at least every two years. For Li-Cor sensors this really holds even for continuous measurements in harsh climates. I have no experience with other makes.

3) In addition be aware that the absolute values, and the ratio between above and below canopy irradiance will depend on solar elevation, as well as on how diffuse daylight is. This last point means that measurements on cloudy and sunny conditions, even if expressed as a ratio will not be comparable.

After writing all this, I need to add that in my experience the two most important sources of errors in this type of measurements are: using "subjective" sampling (not well designed protocol for deciding at which points under the canopy to take readings in an objective way), insufficient replication to account for the high spatial heterogeneity and shading (most frequently partial shading by the operator).

Pedro.

Dear Hasnain,

Maybe attached publication can help you.

Kind regards,

Predrag

Sodium is not always harmful  to crops , rather it lessens the load on potassium having multiple roles to play . Sodium always remains an important  principal cation  as a part of cation exchange capacity of soil , and adds to the soil tilth , but same sodium could be a different dangerous preposition , when the relative distribution exceeds the  other cations like calcium and/or magnesium.

I think it is OK to determine the enzymatic antioxidants in the cotton cotyledons under NaCl and drought stresses. I disagree with Rajesh on using NaCl to induce water deficit since ionic stress will be unavoidable factor. It is better to use PEG polymer of 8000 or more to induce water deficit. PEG 8000 or more decreased the growth medium water potential without entering the cells. It cannot pass through the interstices of the cell wall because PEG is bigger. You have to known this number 8000 is not a real molecular weight.

Greetings

The answer to this may be down to light quality.  Far-red light stimulates bulbing and if plants are densely packed and shading each other there will be a higher ratio of far-red light which would induce earlier bulbing.

Occurrence of high temperature  concomitant with water deficit stress induces two different  type of defense mechanism in higher plants, namely, induction of anti oxidant enzymes and specific  HSPs in cytoplasm as well as in organelles like  endoplasmic reticulum, mitochondria and chloroplast.  Induction of  antioxidant enzymes are reported  under most type of abiotic stresses including high temperature stress. There is direct relationship exists between antioxidant enzyme activities like SOD, peroxidase, catalase, ascobate peroxidase (in chloroplast), glutathione reductase etc.,  with high temperature tolerance in many plant species. 

Dr. K. Annamalainathan

Data for plant concentrations of Al should be treated with some skepticism for two reasons. First, Field grown plants are always contaminated to some extent by soil (typically high Al concentration).  This dust is impossible to remove completely.  The only reliable data for roots are from hydroponics with prior desorption of exchanged Al on the surface. Second, methods of plant digestion may not quantitatively recover Al.

Aquatic plants do not develop in anoxia; they transport oxygen from the atmosphere to the submerged roots via aerenchyma. They are even able to release oxygen from the roots into the sediment avoiding the formation of reducing conditions around the roots

Dear Simona, thank you for the references. In fact, at first we evaluated to obtain ET from remote sensing techniques. This, however, seems not an easy task. Meanwhile, we got measures of water content directly available from a European project and therefore we are trying to better understand how this index relates to ET and primary production

I recently visited a Andean site (paramo) in Ecuador at 3800m and observed many species with rosette growth forms. UV, temperature, and wind were mentioned as possible evolutionary drivers. Can anyone explain the mechanism driving these trends? For example, hormones that promote stem elongation are less active at colder temperatures? Or secondary compounds that act to protect the cells from Uv rays?

Methyl mannas estarase is an enzymes... Dear Enrique. Thanks indeed

first you should autoclave your media, then sterile anything (and your hands) with alchol 70% and a few fire(Spirit lamp) , then keep your cultured media in optimom temprature and light .

To stress the plants, you could use several ways:

1. you can use : salt (NaCl) for salinity stress

2. PEG(6000, 8000,4000) or Manitole ect. for drought stress

3. heavy metal such as Ni, Co, ... for heavy metal stress

Dear friends

Thank you so much

Cactus is the most famous arid plant on holding water where a fully grown saguaro (Carnegiea gigantea) is said to be able to absorb as much as 200 U.S. gallons (760 l; 170 imp gal) of water during a rainstorm.

The classification of the family Cactaceae were shown on the attached files

This depends mainly on your intention and aims of study.

However, as it has been already mentioned, there are limitations of in vitro approach, while working in the field is quite difficult, due to the complex of abiotic (and biotic) factors that influence the whole-plant responses. Nevertheless, in vitro work has the advantage of controlling and manipulating experimental factors, which would give you a more accurate (rather in a numerical way)  picture of plant-salinity interrelationship. On the other hand, the lab approach would never replicate the natural conditions ant thus, the inherent limitations.

For instance, if you have a halophytic species, it would be very useful and interesting to study it both exposed to salinity  in the lab, as well studied in the field - with measured values of EC. Surprisingly (or not), many species may act in a different manner in vitro, in contrast with what we usually think about the degree of salt  tolerance of a given halophyte species. We conducted such experiments  - and found that species usually considered as ”obligatory/euhalophytes” in the field, responded quite negative when exposed to salt stress in the lab, comparatively with species classified as ”less” halophytic.

Overall, depending on your objectives, it is good to always have in your mind these aspects and to adjust and design your work according to them.

@Yuan-Yeu Yau sir please check the link and correct me if i am wrong.

Dear Yang Liu,

a paper that may help:

Journal of Experimental Botany, Vol. 57, No. 3, pp. 449–459, 2006

"Involvement of soluble sugars in reactive oxygen species

balance and responses to oxidative stress in plants"

By:

Ivan Coue´ e*, Ce´ cile Sulmon, Gwenola Gouesbet and Abdelhak El Amrani

Best regards,

Maria Alexou

As I said earlier check for water quality , especially EC .There could be some fungal infection as well.

Amanina,

Positive correlation between Photosynthesis and WUE(i)? Yes and No.

Basically A_N/g_s (Net assimilation / srtomatal conductance) simply indicates the amount of carbon fixed / stomatal conductance if it is  derived from stable  carbon isotopes. Or Carbon fixed / unit water lost if derived from gas exchange measurements. Nevertheless you can find the following: a) increase in WUE with an increasing A while g_s remains constant or increases moderately. b) an increase in WUE if A remains constant but g_s decreases c) decreasing A_N and gs decreases significantly. The latter usually occurs under drought situations. An incerease in WUE does not necessarily mean an increase in A_N or increase in Biomassproduction. E.g. Tree rings often show a decrease while WUE increases (mostly found under increasing or chronic drought). You can find further details under

Saurer, M., R. T. W. Siegwolf, and F. Schweingruber, 2004: Carbon isotope discrimination indicates improving water-use efficiency of trees in northern Eurasia over the last 100 years. Global Change Biology, 10, 2109-2120.

In heat stressed tomato plants, i used the protocol described in the thesis here:

see Page 10

thank you

Deep tillage pulverizes the soil, making it soft and porous. Moreover root penetration is limited if there is a hard pan in the soil and hoeing can improve. This condition helps the roots to go deeper in the soil. Usually this is done while soil is being prepared for sowing of crop. In standing crop it may care must be taken as it may damage the root system and have bad effects. In your experiment did you hoe the field in standing crop?

Alternatively, you can use tea bags for sterilization after dipping the bleach solution and mixing 300 rpm for 10-15 min. If you have relatively small seeds like orchid seeds, perform the surface sterilisation in micro-cenrtrifuge tubes ( 2mL volume) filled with a bleach solution. Mix it briefly and repeat the steps two-three times, in each please replenish the solution using an autoclaved yellow tips. Finally, add water only 2-3 times. Suck up the seeds and placed onto the germination medium using a micro pipet.

Mr. James,

You may find helpful the attached file with regard to your question.

In any case, I agree with Mr. Chidiac, suggesting strongly experimentation. At the beggining you may fail but surely if you persist you will succeed.

Best Regards

I canonly add another link to a road side effect in NZ https://researcharchive.lincoln.ac.nz/bitstream/handle/10182/820/aeru_rr_156.pdf?sequence=1, For all kind of claim it seems advisable to run in situ tests by using upwind and downwind positions

you must  do the drought stress for each species  separately, but the treatment s must be the same. then it is very easy to compare different species response, providing you have enough replications for each species.

Thanks so much Mr. Abhishek Raj for your very informative articles. 

Hello,

I worked on this a PhD student 50 years ago!

At the risk of repetition and being egotistical you might like to read :

Lawlor DW (1969)  Plant Growth in Polyethylene Glycol Solutions in Relation to the Osmotic Potential of the Root Medium and the Leaf Water Balance  J. Exp. Bot. 20 (4): 895

Lawlor Dw (1970) ABSORPTION OF POLYETHYLENE GLYCOLS BY PLANTS AND THEIR EFFECTS ON PLANT GROWTH.  New Phytologist

DOI: 10.1111/j.1469-8137.1970.tb02446.x

Both are available on Research Gate

Regards

David Lawlor

Dear Akila,

Your aim to analyse drought responses in soil has been tried many times. The method you suggest, and supported by others, may seem straight-forward but I have to say is superficial and will tell you little of value , especially if you think of comparing different plant species, varieties etc.  I have dealt with the problem and show what needs to be done as treatments and measurements to arrive at a better understanding of the problem.  Some think that such detail is unnecessary, but after 50 years studying plant water relations I am sure that only by a deep analysis can progress be made.  .  Please read:

 Lawlor DW (2013) Genetic engineering to improve plant performance under drought: physiological evaluation of achievements, limitations, and possibilities.. J Exp Bot. 2013 Jan;64(1):83-108. doi: 10.1093/jxb/ers326. Epub 2012 Nov 16.

The application of these methods and ideas to a practical problem of comparing wheat in-bred lines in a pot experiment is described in :

Habash DZ, Baudo M, Hindle M, Powers SJ, Defoin-Platel M, Mitchell R, et al. (2014) Systems Responses to Progressive Water Stress in Durum Wheat. PLoS ONE 9(9): e108431. doi:10.1371/journal.pone.0108431

The results are very interesting  and worth careful reading.

Both papers are available under Lawlor DW on Research Gate

I am happy to help further.

Regards

David W Lawlor

Thanks you all

Microgravity is the condition in which people or objects appear to be weightless. Means the individual quantum particles situates a resultant gravity which is theoretically equals to zero.

In the case of plants the chlorophylls are formed with huge number of quantum particles within. As the micro-gravity is said the photosynthesis must not be affected by this issue. But as the hormonal systems affects by the micro-gravity, the photosynthesis or photosynthetic activities could be affected. 

It is well known that different plants are having different different cycles like C1, C2, C3, C4 etc. and all of them are mutually dependent on photosynthesis for that reason the photosynthesis would be affected if the cycles got imbalanced. This is my best to give the answer regarding your query.

thanks Mr. David Lawlor

I am happy to communicate with your presence

Bananas are chilling sensitive plants.   Below about 12C, the membrane lipids change conformation to make the membrane more rigid.   As many of the electron transport functions are membrane bound or closely associated, their ability to pass electrons along the chain is impaired.    With respect to leaves, the bronzing or similar discolouration is due to photo-destruction of chlorophyll as electrons can not be passed.   Free radicals can also be generated resulting in further destruction of various compounds especially those with double bonds e.g. unsaturated lipids forming peroxides.

When u say absorbance, what do u mean? Most likely u will be performing a kinetic assay. Additional details might be needed if your query needs to be answered.