Absorption of Cations by Roots. Effects of Hydrogen Ions and Essential Role of Calcium

Rains, D. W.; Schmid, Walther; Epstein, Emanuel

doi:10.1104/pp.39.2.274

Cited by 95 publications

(64 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 1 shows that 0.1 and 1 juM CaCl2 increased the tiptake of selenate or selenite in both species. This Ca effect (20,30) has been noted in many other systems and has been explained in variouis ways: as stabilizer of membranes (16,28,31); as antagonist to interfering ions (12); as a com'ponent of enzyme systems (27) ; and as neutralizer of the detrimental effect of EDTA on roots (2,9). CaCl2 is also beneficial dturinig the uptake of sulfate which is physiologically and] biochemically quite similar to selenate (15).…”

Section: Methodsmentioning

confidence: 99%

Selenium Absorption by Excised Astragalus Roots

Ulrich

Shrift

1968

Plant Physiol.

View full text Add to dashboard Cite

A bstract. Absorption of selenate and selenite by excised roots of A stragalus Crotalariae, a selenium accumulator, and of A. lentiginosus, a non-accumulator, was favored by CaCl, and a pH of 4.0. The uptake of selenate and possibly selenite, is metabolically linked. Roots of a number of Astragalus species were examined, and in all cases selenate entered the roots muoh faster than selenite. In these short-term experiments there was no relation between uptake of the 2 ions and classification of a species as selenium-accumulator or non-accumulator.

show abstract

Section: Methodsmentioning

confidence: 99%

Selenium Absorption by Excised Astragalus Roots

Ulrich

Shrift

1968

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Distilled water, of itself, is probably not damaging. But Epstein and co-workers have shown that root cell membranes may be damaged by hydrogen ions (Rains, Schmid & Epstein, 1964) and sodium ions (Cramer, Epstein & Lauchli, 1988) unless protected by some calcium ions. In the present experiments any such effects were probably absent.…”

Section: Aeroponic Culture Systemmentioning

confidence: 99%

Rates of water uptake into the mature root system of maize plants

1993

View full text Add to dashboard Cite

SUMMARYA new method of measuring water uptake by roots is applied to whole root systems of large maize plants growing in aeroponic (mist) culture. The method depends on the build-up of concentration of dye (sulphorhodamine G) on and in the root surface, when it is fed in the mist. Water enters the roots rapidly, but the dye is separated from the water by osmotic filtration and penetrates the apoplast only by very slow diffusion. The dye accumulates progressively with time on roots on transpiring plants, but not on roots of non-transpiring controls. The rate of accumulation of dye at a place on the root is translated to a flux of water into the root at that place, using the concentration of dye in the mist. Water fluxes were measured into first-order branches and axes over the root system and expressed both as fluxes per unit length and per unit surface of root. Values are consistent with those found by potometric methods for limited samples of young plants. The variance of the measurements is quite large, possibly reflecting real heterogeneities in water uptake throughout the root system. The maximum water uptake achieved by a few branches was 40 //I h"^ cm ' root. On average, flux into axes and branches was the same throughout the root system, at about 5 //I h"^ cm"-. The region of the axis at which the late metaxylem vessels mature and become conducting coincides with the region where the branches become active in water uptake (20-30 cm from the tip). Proximal to this, the branches collect about eight times as much water as the axis, having about eight times the surface area. The zone of maximum water collection by branches and axis is 30-60 cm from the tip (6-8 //I h~' cm~^ axis). In the older, more proximal regions, water collection drops to about a quarter of this.

show abstract

“…Rains et al (15) reported that Rb+ uptake by barley roots from solutions of high acidity decreased with time. The effect of acidity was attributed to injury to the transport mechanism.…”

mentioning

confidence: 99%