Non-metabolic Uptake of Ions by Barley Roots.

Abstract

PLANT PHYSIOLOGY sections (or, rather, on the dimensions of the gaps between the cut surfaces of neighboring sections).) SUMMARYThe variation with tissue dimensions of the halftimes of osmosis and self-diffusion, the manner in which half-times of individual cells vary with cell position within the tissue, and the internal gradients within tissue during such phenomena are analyzed. These processes may be described mathematically by means of a diffusion equation, and the basic parameter characterizing the dynamics of the process is the diffusivity, D. The data of Buffel (1)

Loss of Phosphorus-32 by Plant Roots after Foliar Application.

“…A differential replenishing of root phosphorus by aerial tissues during the test period could well have occurred, for instance, to influence the root loss results. That aerial tissues do indeed influence loss results has already beeni dlemonstrated by Jacobson et al (8).…”

“…of "free" space, the interface barrier to free diffusion of ions in the root is taken as a natural line of division, root "exterior" could be designated on the one hand as any area external to the physical structure of the root itself or again, as certain areas extending to the en(lo(lermis (8). or even to within the stele of the root (4).…”

“…Regulated loss of ions by roots has been envisoned as one means by which the plant is able to maintain electrical neutrality while differentially absorbing companion ions (7,8). Considerable use has already been made of root loss determinations in the development of "free" and "outer" space concepts, and the volumetric measurement of such space (3).…”

“…These variables are interrelated: the relation of germination to temperature is dependent on the light treatment and conversely the relation of germination to light treatment is dependent on the temperature. (2,4,8,9) Using standard methods, a complete study of the interrelation of these 2 variables, on the rate or attainable percentage of germination of a single strain of seed, requires the correlation of a large number of separate measurements. It seemed likely that the crossed gradients principle might be useful for seed germination experiments.…”

On the selective adsorption of cations in the cell wall of the green algaValonia utricularis

“…These conditions have long been recognized, and were closely investigated by many authors (Williams & Coleman, 1950;Burstr6m, 1951;Epstein, 1955;Kramer, 1956;Jacobsen et al, 1958;Lundegardh, 1958}. In marine algae, however, the r61e of the cell wall in the mineral metabolism has scarcely been considered.…”