http://plantstress.com/methods/ZIM%20method%20in%20wheat.pdf 

There is more explanation about drought stress method: plantstress.com 

My advice is that if you know soil water capacity (field capacity) (if you do not know and you are just going to start new experiment, you can obtain yourself with doing a small experiment in your soil), you can measure with watermark or ADC (decagon) in order to collect data and even your plants did not show drought symptoms, you can know if they are suffering with water deficit or not.

I am working with grapevines, so even ADC decagon sensors indicate drought stress, the grapevines are still resisting to declare dought symptoms like few days (depend on the envieronmental conditions).

Thank you Tefide, presently going through the links you sent.

dear Olive, I think you mean that your need to know  which of screening techniques are suitable to assess drought tolerance when drought occurs during reproductive stage. so you can measure all plant characters that are affected by the terminal drought stress. such as time of anthesis, chlorophyll content at anthesis, leaf rolling, waxiness, stay green, total soluble sugars on the flag leaf, leaf water potential during reproductive stage, root length and density. duration period of grain filling, and days to maturity. then the yield components, such as kernel weight, kernel size, number of kernels/spike, number of spiklets/spike. 

I would add Canopy temperature and canopy spectral reflection (CSR) and water indices such as NDVI, as well as stomatal conductance ans relative water content to Dr. Abdelmula answer. It all depends on what resources for phenotypyping you have. The root method is good but it is destructive. 

Thank you Dr. Abdelmula, hope you got my message. @ Wahid, thanks. Since my focus is drought stress at the reproductive stage, i have no need for the root method. Stomatal conductance is a very good stress indicator, i will add that, thanks

Dear Olive

If I were you I measure relative water content (RWC) of leaf, osmotic adjustment (OA), canopy temperature, chlorophyll content by SPAD, stomatal conductance and Proline. High correlation exists between RWC and canopy temperature . Also, grain yield is very important.

Dear Sanaz,

Thank you

Dear Olive

I with agree most of mentions in additional, I think the root trait is it important for correlation with yield, such as root length number of root, root weight and root distributions, special in some types of soil.

Many thanks Salih. Measuring root traits can be a bit challenging, i would like to concentrate the measurements on above-ground plant traits for now.

It is possible to measure root growth using a non destructive method if you use a glassy tube close to roots. You can use a scanner inside the glass each 10 days.

That is very interesting Dr. Walter

Dear Dr Olive,

I would like to thank you for your question. Drought is important abiotic stress. During my Ph D in Germany, I have used a simple and more simple methods used in wheat. Using this methods I have mapped some QTLs for stem reserve mobilization and some grain traits. 

This investigation was carried out in field during the wheat growing season. The experiments were arranged in a randomized complete block design with two

replicates. Each replicate consisted of one plot per genotype with four rows, 1 m long, with 20 cm between rows. The soil type at the experimental site was silty loam. All plants in each plot were harvested in bulk when the plants reached maturity.

Drought test

Anthesis was recorded when about 50% of the plant showed spikes with exerted anthers in the central third of the spikes. Fourteen days after anthesis,  chemical desiccation was applied to two rows of the plot of each genotype, while the other two rows were kept untreated (without desiccation). The desiccation treatment was applied by spraying the whole plant canopy to full wetting with an aqueous solution of potassium iodide (KI, 0.5 % w/v). The desiccant was applied using a hand-held boom sprayer allowing spray penetration to the whole plant canopy.

Drought scoring

At maturity, the spikes were collected and threshed on a plot basis. After harvest,

1000-grain weight was estimated for treated and non-treated rows. In the final testing, the post-anthesis drought tolerance index of a pre-specified seed bulk was estimated from the performance of the stressed rows (S) relative to its respective non-stressed control rows (C) within the same replicate and calculated as percent according to Blum et al. (1983a, b): Calculation of stress tolerance index (STI) % = [(S/ C) x 100], where C = 1000-grain weight under control and S = 1000-grain weight under potassium iodide (KI) treatment.

I wish you best regards

Waiting your comments 

with best regards

Khaled

Dear Dr. Khaled,

Thank you!!, the drought scoring method is great i will use it in my next experiment,  I will also like to know the result of your thesis after the KI treatment. My drought stress treatment is pre-anthesis, targeting gametogenesis and the screening method i have reviewed so far involves microscopy, i am looking for a phenotypic or morphological trait that has an association with pollen sterility/ viability.

In my first screening a used one Egyptian wheat cultivar, Giza 150; and it gave me a very interesting result. Please do you have any records on the performance of this cultivar. 

Thank you. Eagerly waiting for your comment

Kind regards,

Olive