You could use dental paste to take an imprint of the leaf and then take a nail polish film from that to measure stomatal density and pore opening.

The idea is that you take a quick setting (usually two components) dental paste and put a small amount in a small petri dish (or other container). Then you push the leaf gently onto the drying paste. Within a minute (or shorter) the paste has hardened and you can remove the leaf. Now you have an imprint of the leaf in the dental paste that is easily stored. Later you can apply clear nail polish to the imprint, peel that off once it has hardened and image the peel under the microscope. Based on the pore size and densities you should be able to calculate stomatal conductance.

Caveat is of course that you don’t know how much the pore opening is adjusted while the dental paste is hardening.

Dear Swapna Simon

You might infer it meassuring the ostiole area by the anatomical analysis of epidermis. The advantage of epidermis analysis is that you needn´t include tissues in parafine and you can obtain semi-permanent preparations to analyze by microscope.

In my case, i have meassurments of stomatic conductance and they fit well with results obtained by epidermis analysis. But the correlation of both variables wasn´t the objective of my research.

Good luck, and best regards from Argentina

Thank you   Andries Temme,  Sayed Haleem Shah and Rosalia Paz 

Your are advise and suggestions are really valuable.

The best method that I used before is infrared camera (Infrared Thermal Imager ). You can take only one photo and you understand the canopy temperature. Canopy temperature is highly correlated with stomatal conductance and relative water content (RWC).

But, if you do not have infrared camera you can score the amount of leaf rolling. May be this method has some errors, because some of the genotypes have rolling leaf also in non stress condition.

I agree with Haleen Shah, but if there are not posibilities to have or adquiere a prorometer or IRGA, you can use the dental technique but the results don't have the exactitude of the equipments

I have also used the nail polish trick mentioned by Andries, with some success. However it’s important to note that the nail polish method measures morphology, to get into the physiology world you will need some instrumentation. You will want to use of a porometer or a gas exchange instrument. The advantage of using a complete system like a Pn analyzer is that you may find other physiological correlations to abiotic stress beyond stomatal conductance (which you are limited to measuring with a porometer). Please let me know if you would like to talk more about the physiological options as I have had experience with certain instruments that I believe you would find very helpful. Thanks!

Maybe you can use the leaf water loss experiment. In this way you need to cut the leaf and place it in a highly sensitive balance in a test room. Through the amount of water that lost diuring time you can calculate the transpiration rate by knowing the area of the leaf that you are using for this experiment. Although it is tranpiration rate of the leaf but it can give you a nice indication related to stomatal pore area which is also correlated with stomatal conductance as well.