INVESTIGATIONS INTO THE OCCURRENCE OF ACTIVE AND PASSIVE COMPONENTS IN THE ION UPTAKE BYVICIA FABA

Determination of Hydraulic and Osmotic Properties of Soybean Root Systems

“…With the use of this model, a possible cause for the so-called nonosmotic water uptake was demonstrated which in principle was due to a standing gradient effect such as was described by Anderson et al (1). In addition, Fiscus (7) was able to show that the nonuniform distribution of root properties can also account for the complex root resistance profile changes reported by Brouwer (2,3).…”

Kinetics of rubidium absorption & translocation by barley

“…These observations are typical of a strict competition, again indicating a similarity in mechanism between shoots and roots. Inhibitors-metabolic, like azide and methylene blue; uncouplers, like DNP; and competitors, like hydrogen ion-have also been shown to affect active ion accumulation in roots (3,10,13,16,20,26). When measuring ion accumulation in shoots it is necessary to establish experimentally that the inhibitor does not affect transpiration since transpiration may affect ion accumulation.…”

“…The transport of ions from a bathing solution to the top of a plant has been described as a passive (7,8,18,19,22,23,28) and active (2,3,17,26,27) process. Brouwer (3) states that at least 70 to 85 % of the ions appearing in the tops of plants go through an active process, i.e., "owing to a mechanism controlled or started by metabolism lands into the transpiration stream".…”

“…Brouwer (3) states that at least 70 to 85 % of the ions appearing in the tops of plants go through an active process, i.e., "owing to a mechanism controlled or started by metabolism lands into the transpiration stream". On the other hand, Epstein (7) concludes that "the cells of the roots, as well as the slhoots, derive their ions from the solution in the 'outer' space of the root tissue".…”

Non-metabolic Uptake of Ions by Barley Roots.

“…The concept of free and apparent free space in roots (2,10) has been given considerable attention, especially in its relation to absorption and translocation of solutes (3,6,9,11,18,20). However even with anions, the values of apparent free space obtained for a given root material are dependent upon the methods used for their determination (4).…”