Re: what is the value of the osmotic potential of the cell sap of onion epidermal cells

The osmotic potential of the cell sap in onion epidermal cells (or any 
plant cell, for that matter) can vary greatly depending upon how the cells 
have been treated - e.g. depending on exposure to drying, temperature, 
etc.  Between 630 to 470 mosm seems to be the range of values I've found 
in a quick seach of the lierature.  See:

PALTA, J. P., LEVITT, J., STADELMANN, E. J. & BURKE, M. J. (1977)  
Dehydration of Onion Cells: A Comparison of Freezing vs. Desiccation and 
Living vs. Dead Cells.
Physiologia Plantarum 41 (4), 273-279.


PALTA, J. P , LEVITT, J., & STADELMANN, E.J. (1977)  Freezing Injury in 
Onion Bulb Cells  I. Evaluation of the conductivity method and analysis of 
ion and sugar efflux from injured cells. Plant Physiol. (1977) 60, 393-397