I do not know , which kind of germplasm , you are intending to screen under pot culture conditions. But , let me  tell , most of the pot culture screenings have not been able to produce replicative results over time and space, unless similar simulative conditions are created matching to  natural climatic conditions represented by those germplasm.  We were discussing more or less similar issue on ResearcGate about the screening of germplasm for salinity tolerance . Age of the plant , the major determining factor towards outcome such screening results . Eventually , when screened germplasm through pot culture are taken to field , they fail to display that level of tolerance . The best use of pot culture studies    is to identify some plant physiological parameters indicative of drought tolerance , they will be more useful than  declaring the drought tolerance in ultimate terms about a given germplasm(s)

This is a question without a simple answer. The answer depends on the plant species, the timing, duration and severity of the drought stress you aim at. There is no way around it - you must study the subject matter. You may start with the book and the Plantstress web site which offers access to study materials. Furthermore, there are professors at Tamil Nadu Univ. who are experienced on the subject and can advice you, Prof Chandra Babu for example.

The number of accessions can be narrow down with morphological characters of the plants related to drought resistance. However, the screening depends on the plant characters as well as the environment.

The purpose of rapidly screening a large germplasm collection is to narrow the candidate pool to a point in which more intensive physiological, molecular, and genetic methods can be applied to identify specific drought-tolerant traits in either the lab or field. For screening of large collection of germplasm lines is based on identifying drought-tolerance traits relevant to yield attributing character and testing them in target environment. For this require trait based breeding approach and trait pyramiding is the key. Drought tolerance can be improved only by bringing together diverse adaptive mechanisms/ traits. The significant progress is made in identifying relevant traits like water relations and cellular level tolerance. The mechanisms regulating water relation e.g Water mining - WUE - Water conservation (waxes /stomata). Mechanisms governing the cellular level tolerance: Protein turnover - Oxidative stress - Cell cycle, Survival & recovery on induction. During stress conditions effect on flowering response, stay green character, remobilization of resources. And finally accurate phenotyping is crucial for validation of the trait of interest (Prof. Uday Kumar (http://birac.nic.in/webcontent/dr_uday.pdf).

Hello

It seems as if this question just keeps being asked and the answers are ignored. If you are interested please look at my earlier responses and suggestions how to deal with assessing `drought resistance' .