CHARACTERISTICS OF WATER EXCHANGE IN STORAGE PARENCHYMA OF THE SUGAR-BEET (BETA-VULGARIS L) ROOT IN RELATION TO SUGAR ACCUMULATION

We used the intracellular pressure probe technique and the method of relaxation of intracellular pressure to determine turgor pressure P(t), the volumetric elastic modulus of cell walls epsilon, and hydraulic conductivity of cell membranes L(p) in storage parenchyma of sugar beet and fodder beet roots. In mature roots of sugar beet, P(t) and epsilon attained values of 1.8-2.0 and 16 MPa, respectively, which are significantly greater than values characteristic of higher plants, including values obtained in the present work on fodder beet by way of comparison (up to 1.4 and 7.0 MPa, respectively). Values of L(p) were five times lower in storage parenchyma of sugar beet than in storage parenchyma of fodder beet. The investigated water exchange parameters are analyzed in relation to tissue sucrose concentration and water potential values during the ontogenesis of sugar beet. In addition to this, the nature dependency of epsilon and L(p) on P(t) is also analyzed. The role of the investigated parameters in concentration of sucrose and limitation of this process in cells of sugar beet root storage parenchyma is discussed in the work.