Weight range isn't specified, instead you need to compare it with the leaf weight of control plants randomly, if you want to include this parameter in your data.

You can use other parameters like biochemical, drought marker genes etc. to find whether the genotype is tolerant or succeptible.

Dear Salvadora

Since the most important parameter participating in photosynthetic performance of the plants is leaf area, and environmental conditions (e.g. drought) can considerably influence it, I believe it can give you a good critrion for genotype selection. Specially on the early step of plant development when the leaf area index is the main limiting factor for crop photosynthesis if it encounter to drought stress the role of specific leaf area (SLA) would be emphesised. Since some genotype are different in this respect I think apart from vegetative parameters, SLA can help you a lot for screening between genotypes.

Cheers

Sasan

Salvadora,

this paper may help you.

http://www.amjbot.org/content/96/3/605.full#ref-11

There was an unexpected increase in SLA with drought (See Figure 1). 

See also Dudley, 1996 for a review: 

Dudley S. A. 1996. Differing selection on plant physiological traits in response to environmental water availability: A test of adaptive hypotheses. Evolution 50: 92–102.

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Often Slw variations depend on mean leaf area reduction or leaf thickness change. You should then extend the analysis to plastochron, chlorophyll content and leaf area duration, as in https://dl.sciencesocieties.org/publications/aj/abstracts/85/5/AJ0850050987 refs