Migration of Salts and Water into Xylem of the Roots of Higher Plants

Crafts, A. S.; Broyer, T. C.

doi:10.2307/2436683

Cited by 88 publications

(40 citation statements)

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“…The addition of both chloride and sulphate salts (24-hour averages) reduced calcium concentrations relative to the control plants, left magnesium unchanged, caused a marked increase in sodium, a marked decrease in potassium, and had little effect on total nitrogen and phosphate concentrations. 5. The accumulation of chloride in the control plants was notably high (72 m.e.…”

Section: Plant Physiologymentioning

confidence: 91%

Effect of Saline Substrate on Hourly Levels of Carbohydrates and Inorganic Constituents of Barley Plants

Gauch

Eaton

1942

Plant Physiol.

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IntroductionSalinity considerations are likely to be an important feature of irrigation agriculture wherever it is practiced. The fact that a depressed growth of many plants results from even moderate accumulations of chloride and sulphate salts in soil solutions has a highly practical significance. From the standpoint of the investigator, it is particularly desirable that the mechanism of salt injury be as clearly understood as our present-day insight into biological processes will permit.The investigation reported in this paper had the two-fold objective of determining (a) if any relationship existed between salt accumulation in the barley plant and the hourly march or levels of carbohydrate accumulation; and (b) the relation between cyclic changes in transpiration rates and the accumulation of the chemical constituents of the substrate in the shoots of barley plants.Measurements were made of the concentrations of sugars, starch, and inorganic constituents in 5-week-old barley plants at 4-hour intervals over a 24-hour cycle. The three sets of plants compared were grown in sand cultures supplied with solutions as follows: (a) base nutrient only; (b) base nutrient plus 100 milliequivalents per liter of added chloride; and (c) base nutrient plus 200 milliequivalents per liter of added sulphate.

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Section: Plant Physiologymentioning

confidence: 91%

Effect of Saline Substrate on Hourly Levels of Carbohydrates and Inorganic Constituents of Barley Plants

Gauch

Eaton

1942

Plant Physiol.

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“…However, in spite of extensive study, little is known about the mechanism by which salt is moved into the xylem vessels. According to the most often cited theory of radial salt transport in roots, salt is accumulated by the cortical cells and moves inward through the symplast by diffusion, perhaps aided by cytoplasmic streaming, to the stele where it leaks out of the stelar parenchyma cells into the xylem (4). This theory was strengthened by observations of Laties and Budd (10) who reported that cells of the stele are both leaky and ineffective in salt absorption when first removed from the stele and only accumulate salt effectively after 24 hours of incubation in solution.…”

Section: Studiedmentioning

confidence: 99%

Radial Salt Transport in Corn Roots

Yu¹,

Kramer²

1967

Plant Physiol.

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Summtiizary. Primary roots of solution--grown, 5-day-old or 6-day-old seedlings of corn (Zea mays L.) 10 to 14 cm in length were used to study radial salt trtansport. Measurements were made of the volume of root pressure exudation, salt concentration of the exudate, and rate of salt movement into the xylem exudate. The 32p uptake, 09 consumption, and dehydrogenase activity of the root cortex and stele also were studied.These roots produced copious root pressure exudate containing 4 to 10 times the concentration of 32p in the external solution. Freshly separated stele from 5-day-old roots accumulated 32p as rapidly as the cortex from which it was se!parated and the stele of intact roots also accumulated 32P. Separated stele hfas a higher oxygen uptake than cortex. It also shows strong dehydrogenase activity with the tetrazolium test. The high oxygen consumption, 32p tuptake and strong dehydrogenase activity indicate that the cells of the stele probably play a direct role in salt transport.These data raise dotubts concerning theories of radial salt transport into the xylem based on the assumption that the stele is unable to accumulate salt vigorously.

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“…Apoplastic transport of solutes into the stele is prevented by the Casparian band located in the cell walls of the endodermis. According to the symplast theory (Crafts & Broyer 1938), a continuum of cells connected via plasmodesmata extends from the rhizodermis into the stele and allows radial diffusion of nutrients from the site of uptake to the site of release into the xylem vessels. Part of the evidence for this theory comes from electrophysiological studies on roots.…”

Section: Introductionmentioning

confidence: 99%

Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

Wegner

Sattelmacher

Läuchli

et al. 1999

Plant Cell & Environment

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Upon addition of nitrate and ammonium, respectively, to the bath of intact 'low salt' maize plants, the cortical membrane potential and the trans-root potential changed in a similar and synchronous way as revealed by applying conventional microelectrode techniques and the xylem pressure-potential probe (Wegner & Zimmermann 1998). Upon addition of nitrate, a hyperpolarization response was observed which was frequently preceded by a short depolarization phase. In contrast, addition of ammonium resulted in an overall depolarization response both of the cortical membrane potential and the trans-root potential. The nitrate-induced hyperpolarization response and the depolarization following the addition of ammonium were concentration-dependent.The data suggest that a tight electrical coupling exists between the cellular and tissue level in the root of the intact plant and that the resistance of the cellular (symplastic) space is much less than the resistance of the apoplast.

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Migration of Salts and Water into Xylem of the Roots of Higher Plants

Cited by 88 publications

References 0 publications

Effect of Saline Substrate on Hourly Levels of Carbohydrates and Inorganic Constituents of Barley Plants

Effect of Saline Substrate on Hourly Levels of Carbohydrates and Inorganic Constituents of Barley Plants

Radial Salt Transport in Corn Roots

Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

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