The Effect of Calcium on the Uptake and Distribution of Sodium in Excised Barley Roots

Abstract

The total uptake and relative distribution of Na+ along the root was investigated in excised barley roots (Hordeum vulgare L. cv. Union) of 6‐day‐old plants cultured on 0.25 mM CaSO4. One technique involved cutting the roots at harvest time after different uptake periods into different segments each 2 cm long. These segments were ashed and sodium was measured by flame photometry. For each experiment two treatments were done, one containing calcium in the uptake solution and one without calcium. A second technique involved the measurement of sodium transport, using labelled 22Na+ solution. Although no significant differences could be found between the calcium containing and the calciumless treatments at 24 h, there were clearcut differences for the first 6 to 8 h. The effect of calcium on the first stages of the sodium uptake was a large accumulation of sodium in the part close to the apex with a translocation close to nil; whereas the sodium taken up in the absence of calcium did not accumulate in such large amounts in the apex region but was immediately transported basipetally.

Absorption de sodium, calcium et potassium lors d'interactions ioniques au cours de la phase de germination de Raphanus sativus

“…1 Ces observations permettent d'apporter une nuance au fait gCnCralement Ctabli que le calcium a un effet nCgatif sur l'absorption du sodium (18,21,26) en rnodifiant les surfaces cytoplasrniques et l'accession des cations monovalents aux sites d'absorption (8,12,18), en retardant le transport de cet ClCment (30), ou en diminuant l'accumulation du sodium dans le xylbme. Nous devons noter cependant que des tissus jeunes non vacuolCs (2 1, 26) manifestent une prCfCrence pour le sodium en prksence de calcium; ceci expliquerait donc le phCnombne pour nos jeunes plantules, mais non pour des plantes adultes de cette meme espbce, ou dans les racines, le calcium n'interagit pas avec les cations monovalents (20).…”

“…Les interactions des cations sont CtudiCes le plus souvent sur des racines excisCes, ou des plantes entieres, au cours de leur dCveloppement; ces Ctudes ont montre que 1'entrCe de sodium dans la plante depend de sa concentration dans la solution exteme (1,18), de la prCsence de potassium (4,14,25) ou encore de celle de calcium (12,21,26). D'autre part, la possibilitC d'une vie vCgCtale sur milieu salin apparait liCe, dans une large mesure, au maintien d'une certaine richesse en calcium et en potassium dans les tissus vCgCtaux; en effet, Le Saos (1 8) a montrC chez Cochlearia anglica la relation entre une meilleure croissance de la plante en fonction des doses de sodium, et sa teneur en calcium.…”

Effects of low pH and Al on absorption and translocation of some essential nutrients in excised barley roots

“…In the current study, emphasis was placed on the response of individual fractions in the sequence of absorption and translocation (accumulation, cortical efflux, redistribution, and xylem exudation) to H + and A1 toxicity. The investigations were carried out using a multicompartment transport box (Neirinckx and Stassart 1979;Kawasaki et al 1984), radioisotopes, and excised barley roots. Use of a multi-compartment transport box together with a radioisotope tracer technique enabled to separate individual fractions in the sequence of absorption and translocation in tracer studies with excised roots.…”

The absorption and translocation of ions in excised barley roots: A multi-compartment transport box experiment

“…To analyze in more detail the ion absorption processes, it is necessary to examine the translocation along plant roots, as well as the absorption by plant roots, under various environmental conditions. Several researchers (1)(2)(3)(4) have used a transport box to observe the translocation of ions and other substances in excised plant roots. During the course of an investigation on the effect of water-and salt-stress on ion absorption in plants, we also used a "multi-compartment transport box" (5), a modification of the transport box mentioned above.…”