Differences for bound water content as estimated by pressure-volume and adsorption isotherm curves

The non-osmotic volume of PV-curves doesn't correspond to the water fraction bound to the charged or polar sites of macromolecules as determined by AI-curves. The qualitative parameters, in contrast to quantitative parameters, may be affected by common physical-chemical factors: the changes in the amount of strongly bound water in tissues were independent from those in the weakly bound fraction; in contrast an increase in tissue affinity for strongly bound water implied a simultaneous increase in the affinity for weakly bound water. The qualitative properties of bound water may be particularly important for drought adaptation in durum wheat, being associated with the solute potential and with the succulence degree of the leaves.