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

you could study the effect of drought using the following treatments:100% field capacity, 75%,50% and 25%. you could use vegetative growth characteristics to monitor the effect,as well as changes in soluble carbohydrates, proline, glycine betaine, and ABA.  you could ,of course, use leaf water potential to express various levels of drought.

Jiffy pots moistened at 200% and then water withholding at 25 30 and 35 d after sowing. This type of pot allows a high percentage of water relative to total weight is sensitive to stress and can be managed in the field with a simple shelter and a pan, Method in http://www.plantphysiol.org/content/154/3/1254.full

I think the following papers which are both free and open access can help you:

Bouchabke, O., et al. (2008). "Natural Variation in Arabidopsis thaliana as a Tool for Highlighting Differential Drought Responses." PLoS ONE 3(2): e1705.

Aliniaeifard, S. and U. van Meeteren (2014). "Natural variation in stomatal response to closing stimuli among Arabidopsis thaliana accessions after exposure to low VPD as a tool to recognize the mechanism of disturbed stomatal functioning." Journal of Experimental Botany 65(22): 6529-6542.

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

It is nice to include the weight when watering to supplement the amount of deficit water from the pre calibrated at different field capacity proportions. However, in the absence of measuring instruments like tensio-meter or gravimetrically from a mixed soil from top and below surface, htings may go wrong with time, for the growth rate of the experimental plants at different water deficit conditions is different and you add different plant weight with time. Moreover, if the amount of water you add is small you may measure false positive gravimetric value. It is really difficult to acheive more precise methodology but you can do like you proposed more accurately in green houses using plant pots than at field in drought studies.

Keep in touch

You have to do the following

1.  Measure the field capacity of your soil say it is 30% (0.3)

2. measure the real wilting point of your soil say 20% (0.2)

3. measure your soil bulk density

4. calculate the available water capacity (AWC) of your soil 0.3-0.2 =0.1

Set your irrigation levels say (irrigation would be whenever 0, 25, 50, 75 and/or 100% depletion of  AWC

Calculate the applied water for each irrigation and for each level of irrigation = root depth*Soil Bulk density* 0.1 multiply by either 0.25, 0.5, 0.75 and or 1

5. By this you can find the breaking point the barrier between adequate irrigation and drought suffering and with aggravated drought you can monitor switch off/on genes

you can also divide the plant life into three or more physiological stages to find out which stage are more drought susceptible    

It really depends on what your question is. Are you trying to simulate real conditions or controlled conditions (unnatural)? Setting a specific water level is controlled but not natural. Soils in the field dry out gradually, not like harsh osmotic shocks or set levels each day. Gradual changes give plants time to adjust and respond to the stress. Set levels give precision and control, which allows more precise analysis and conclusions. Another complication is that plants are exposed to high light in the field (and temperature changes), which causes a whole lot of other stress responses such as photoinhibition, that may not occur in a growth chamber. These are some of the main reasons I think that "tolerant" plants do not behave in the field as they do in growth chambers and greenhouses. I hope that helps.

There is quite a problem in treating spring ephemerals like A. thaliana that end cycle in 5-6 weeks as a crop. The use of this species is due to the ease in doing fast cycles in green house or in a cabinet and root zone is quite small to make difficult a true field experiment. You may use potted plants in controlled daylenght and moderate temperature under a simple shelter, but soil density should be quite low to allow a precise measure of water stress by weight variation in small pots. With the best