Influx und Efflux bei der Kaliumaufnahme junger Gerstenwurzeln

Mengel, K.

doi:10.1002/jpln.19641060302

Cited by 18 publications

(4 citation statements)

References 6 publications

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“…If, however, under these experimental conditions the use of Rb-86 also does not clearly reflect the uptake of K+ (see also West and Pitman 1967;Schaedle and Jacobson 1967;Jescbke 1970), it must be concluded that both cations behave differently during the uptake process itself. It must, however, be mentioned that this different behaviour of both ions has nothing to d o with an effect often discussed in experiments with labelled ions (Mengel 1964; namely that the influx of the labelled ion (radio nuclid) overestimates the net uptake of the element as a result of exchange and efflux processes. This effect of course also takes place when K' is labelled with Rb-86 ( M a a s and Leggett 1969;Hiatt 1970).…”

Section: Discussionmentioning

confidence: 90%

Suitability of Using Rubidium‐86 as a Tracer for Potassium in Studying Potassium Uptake by Barley Plants

Marschner¹,

Schimansky²

1971

J Plant Nutrition & Soil

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Section: Discussionmentioning

confidence: 90%

Suitability of Using Rubidium‐86 as a Tracer for Potassium in Studying Potassium Uptake by Barley Plants

Marschner¹,

Schimansky²

1971

J Plant Nutrition & Soil

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“…To use the rate equation procedure we need to know the relation between I and c (which is QI v) and E and c to substitute into equation 3 When depletion curves are conducted over time periods long enough to have appreciable root growth, the increase in L with t can be accounted for by using the expression: L = Loe'.t (7) where L. is the root length at the start of the experiment and k, measured separately, is a constant describing the rate of L increase with t. This procedure can also be used to measure diurnal changes of K flux into the root by adding K at a constant rate over a period of 1 or 2 days and following the change in K concentration with time.…”

mentioning

confidence: 99%

A Method for Characterizing the Relation between Nutrient Concentration and Flux into Roots of Intact Plants

Claassen¹,

Barber²

1974

Plant Physiol.

284

183

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A method based on the rate of depletion of a nutrient from solution was developed to characterize nutrient flux of plant roots. Nutrient concentration of the solution was measured at a series of time intervals to describe the complete depletion curve. An integrated rate equation, based on a Michaelis-Menten model, was developed and fit to the data of the depletion curve using a least-square procedure. The A procedure was also developed to measure uptake rate at constant concentration by adding nutrients to the pot at a constant rate that matched net influx into the root. This method also provides a means of measuring diurnal fluctuations in net influx rates.Knowledge of the relation between the rate of ion absorption by plant roots and the concentration of the ion external to the root is important for doing plant nutrition studies, for investigating ion absorption mechanisms, and for evaluating mechanisms supplying nutrients to roots growing in soil (6, 10). Hence, a convenient procedure that mathematically describes the kinetics of ion absorption would be useful.Ion absorption rate as related to ion concentration in the external solution has usually been measured using short term absorption by excised roots of isotopically labeled ions from solution (4) and long term absorption by intact plants from solutions maintained approximately at constant concentration (1). In the first, only ions with a convenient isotope for labeling can be studied and in both, separate measurements of uptake rate must be made for each of a graded series of ion con- THEORYWhen roots are in a solution containing salts, ions may move both into and out of the root. The terms we use to describe this ion movement are: influx, movement of ions from the external solution into the root; I, the rate of influx per unit length of root; efflux, the movement of ions out of the root into the external solution; E, the rate of efflux per unit length of root, and In, the net rate of influx per unit root length which is equal to I -E. The values of I, E, and ln in this paper are in terms of root length; however, root surface area, or root weight could be used if desired.When plants are grown in a solution of a constant volume, v, the decrease in ion content of the solution measures the net amount of the respective ion absorbed. The amount of ion in the nutrient solution, Q, is given by equation 1 where c is the ion concentration in solution. Q = cv (1) A plot of Q versus time, t, gives a curve showing the depletion of the ion from solution resulting from plant absorption and is called the depletion curve. The net influx per pot at any point on this curve is given by -dQ/dt. The slope of the curve can be estimated by expressing Q as a function of t and calculating the derivative. A relation Q = f(t) can be obtained by fitting the data using a parabolic spline function (3) or a cubic spline function (13). Both functions consist of a number of segments called splines fixed by the experimenter which describe the relation by a series of parabolic ...

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“…WVhile at a pH of 5.0 or higher, the K loss by 6 day old barley roots was found to be very small, at pH 4.0 a sharp increase in K loss was found to occur, some 40 % of the initial K content being lost in 3 hours to dilute HBr at this pH. In contrast to this, K is lost in large amounts by corn root tips placed in distilled water with a pH of 5.8 (8) and by 2 to 3 day old barley roots to NaCl solutions at a similar pH (16 The effects of Ca upon ion tiptake as well as upon loss of ions from plant tissue have been the subject of many investigations (2,3,4,8,10,11,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Ca has been shown to reduce greatly the loss of K from 6 day old barley roots at pH 4.0 (13).…”

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confidence: 99%

Potassium Loss and Changes in the Fine Structure of Corn Root Tips Induced by H-ion

1966

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Su,nntarv. The effects of H, Ca, and anaerobiosis upon loss of K to ambient solutions, upon changes in the fine structure, and upon the respiration of corn root tissue were studied. In the pH range 5.5 to 8.0 losses of K decreased with decreasing H concentration. Ca reduced K loss greatly in the lower part of the pH range but with increasing pH the effect of Ca declined. Losses of K tinder No were much greater than those measured tinder air but the same effects of H and Ca were found. The effect of phosphate upon K loss was found to depend upon pH, temperature and the state of development of the tissue.In pure H90 or dilute HCl no obvious derangement of the fine structure of meristematic cells was found to occur in 3 hours above pH 4.4 except attenuation of the groundplasm. At pH 4.4 and below, serious injury was found. The presence of CaCl, or NaCl in the treatment solution greatly ameliorated the effect of H, CaCI, being effective at minute concentration (0.01 meq per liter). NaH2P04 was without any great effect. Anaerobiosis at neutral pH produced severe tissue damage.In contrast to anaerobic treatments, aerobic treatments (pH 5.8) resulting in large losses of K were not accompanied by any diminution of the respiratory rate.

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Influx und Efflux bei der Kaliumaufnahme junger Gerstenwurzeln

Cited by 18 publications

References 6 publications

Suitability of Using Rubidium‐86 as a Tracer for Potassium in Studying Potassium Uptake by Barley Plants

Suitability of Using Rubidium‐86 as a Tracer for Potassium in Studying Potassium Uptake by Barley Plants

A Method for Characterizing the Relation between Nutrient Concentration and Flux into Roots of Intact Plants

Potassium Loss and Changes in the Fine Structure of Corn Root Tips Induced by H-ion

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