Uptake and Transport of Ions in Barley Seedlings III. Correlation Between Transport to the Shoot and Relative Growth Rate

Pitman, M. G.

doi:10.1071/bi9720905

Cited by 128 publications

(80 citation statements)

References 13 publications

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“…Again, we have found similar results for K+ uptake, but with slightly longer lags (y) and crossover times (E) (D Lazof, JM Cheeseman, unpublished data). On the other hand, crossover times and lags on the order of hours to days have been reported for other systems (14,15,24), the most obvious difference between those studies and this one probably being that the other studies used seedlings which were severely depleted of nutrients. In similar experiments using 14 d old Zea mays grown on complete nutrient solutions, we have found that up to 15% of the 42K' and 40% of the 22Na' in the plants was beyond the roots (i.e.…”

Section: Resultsmentioning

confidence: 60%

Sodium Transport and Compartmentation in Spergularia marina

Lazof

Cheeseman²

1986

Plant Physiol.

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ABSTRACrIn this paper, a combination of tracer uptake, efflux, and pulse-chase techniques is applied to the problem of compartmentation of Na ' (4Nal) in the roots of intact, midvegetative Spergularia marina (L.) Griseb. plants. An approach is presented for conducting useful compartmental analysis when it is known that the assumptions required for staightforward interpretations of influx and efflux studies are invalid. Linear rates of 2'Na' accumulation in both roots and shoots were attained within at most a few minutes following the start of labeling. Shoot 2'Na contents equaled root contents within about 20 minutes. Analysis of root accumulation rates, and compartmental and pulse-chase efflux studies indicated that the unidirectional flux rates involved were at least an order of magnitude greater than linear rates of root and shoot accumulation. These rapid fluxes involved only a small portion of the total root Na' (about 1%). The results suggest the existence of a small symplastic compartment, distinct from the 'bulk cytoplasm,' rapidly exchanging with the medium, and responsible for delivery of Na to the xylem. The physical identity of this compartment and its physiological significance are discussed with respect to precedents in the literature.The ultimate significance of the study of root level ion transport and compartmentation in higher plants lies in the understanding of the dual role of roots as organs of ion absorption, with physiological needs of their own, and as organs responsible for nutrient resource partitioning within the whole plant. Analysis of the transport processes has been facilitated by the use of isotope techniques which allow increased resolution ofion movements with respect to both time and a large background of nontransported ions.The There has, to our knowledge, never been a consideration of the requirements for interpretable use of isotopes in transport studies using whole plants under conditions in which one could be assured that unidirectional influx was not being measured, and in which the arrangement of compartments was demonstrably not serial. In this paper we will present such a consideration, showing in particular that by combining influx and compartmental efflux techniques, each of which in itself is theoretically invalid under these circumstances, with pulse-chase studies, it is possible to characterize the compartmentation accounting for the observed ion fluxes and the partitioning between root and shoot. We will present results obtained using intact, vegetative Spergularia marina plants growing on 0.2 x sea water medium in solution culture. The particular virtues of this system have been discussed elsewhere in detail (5,6). For the present purposes, we will restrict our consideration to sodium uptake, accumulation, and translocation because of its relatively straightforward transport characteristics. MATERIALS AND METHODSSpergularia marina (L.) Griseb. seeds were collected from plants growing in our growth chambers and were germinated, transferred to solution cultur...

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Section: Resultsmentioning

confidence: 60%

Sodium Transport and Compartmentation in Spergularia marina

Lazof

Cheeseman²

1986

Plant Physiol.

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“…Average rate of Cu transport (/~cu) to shoot was calculated according to the formula of Pitman (1972) as follows:…”

Section: Methodsmentioning

confidence: 99%

Maize growth and uptake of phosphate and copper at different ambient phosphate concentrations

Gill

Merali

Zia

1992

Soil Science and Plant Nutrition

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“…The degree of ion X Calculated by the method of Pitman (1972). § n= 27-36. exclusion at the xylem was then expressed as the ratio between the xylem ion concentration (subscript x) and the external ion concentration (subscript o) x 100.…”

Section: Xylem Concentrationmentioning

confidence: 99%

“…^^Na content was estimated using a low background gas-flow counter (Nuclear Chicago Corporation). Accumulation \jimo\ Na"^ g~^ dry weight of root (DWR) h"^] rates were also calculated by using the equations of Pitman (1972) with data from plants harvested at 28 and 35 d from which dry and fresh weight had been taken and tissue analyzed for ion content using atomic absorption spectrometry (Pye Unicam SP9) of dried material extracted in 100 mol m"ê thanoic acid for 4 h. For both methods, the seedlings had been salinized at 14 d of age and were growing under steady state conditions.…”

Section: Rates Of Ion Transportmentioning

confidence: 99%

SALT TOLERANCE IN THE HALOPHYTE SUAEDA MARITIMA (L.) DUM.

Clipson

Flowers

1987

New Phytologist

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SUMMARYRates of ion transport and transpiration were measured during the day and night in whole seedlings of Suaeda maritima growing over a range of salinities, in order to calculate concentrations of sodium and potassium in the xylem during these periods. Mean sodium concentration in the xylem was maximal at 56 mol m~^ Na with an external salinity of 200 mol m~^ NaCl. The sodium concentration in the xylem was greater in the dark than in the light at all external salinities investigated. Comparison of the external sodium with that in the xylem indicated that sodium was more strongly excluded from the transpiration stream as salinity increased. The mean concentration of potassium in the xylem declined as external NaCl concentration increased, although selectivity for potassium increased at higher salinities. Results are discussed in relation to osmotic adjustment in S. maritima.

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Uptake and Transport of Ions in Barley Seedlings III. Correlation Between Transport to the Shoot and Relative Growth Rate

Cited by 128 publications

References 13 publications

Sodium Transport and Compartmentation in Spergularia marina

Sodium Transport and Compartmentation in Spergularia marina

Maize growth and uptake of phosphate and copper at different ambient phosphate concentrations

SALT TOLERANCE IN THE HALOPHYTE SUAEDA MARITIMA (L.) DUM.

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