Water Uptake and Root Growth as Influenced by Inequalities in the Concentration of the Substrate

Eaton, Frank M.

doi:10.1104/pp.16.3.545

Cited by 76 publications

(31 citation statements)

References 6 publications

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“…Although the older concept of salinity as imposing an osmotic barrier to water uptake no longer seems appropriate, the plant response to salinity, in most cases, still seems to be best explained in terms of a water stress, possibly imposed by decreased permeability of roots to water (1,7,15). Increased resistance to water flow through the plant would certainly increase the already appreciable (10,23) water stress in transpiring leaves.…”

Section: Resultsmentioning

confidence: 99%

Expansion of Bean Leaves and its Suppression by Salinity

Nieman

1965

Plant Physiol.

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Section: Resultsmentioning

confidence: 99%

Expansion of Bean Leaves and its Suppression by Salinity

Nieman

1965

Plant Physiol.

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“…At no time were they higher than the medium itself, as reported for pepper plants (18) (23). However, others have found that transpiration remained low in plants grown under these conditions for several days (7,11,14). Summary Photosynthesis, respiration, and the resistance to CO2 diffusion to the leaf mesophyll cells have been studied in cotton plants subjected to a range of NaCl concentrations for long periods of time.…”

Section: Discussionmentioning

confidence: 99%

Effects of Osmotic Water Stress on Metabolic Rates of Cotton Plants with Open Stomata

Boyer¹

1965

Plant Physiol.

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This research was undertaken to learn whether photosynthesis and respiration are affected by osmotic water stress in the absence of stomatal closure. Numerous studies have indicated that when plants are grown in soil, stomata close as plant water deficits increase (5,20,27). Photosynthesis is reduced under these conditions and the cause of the lower rates generally is attributed to increased resistance of the stomata to CO2 diffusion. However, recent work (21) has shown that reduced rates may not be due entirely to stomatal closure. Effects on respiration are variable (5,20).No studies have been made to establish whether stomatal apertures are affected by long-term water stress arising from high solute concentrations in the root medium. Predictions of stomatal behavior under these conditions can be made from several investigations which have shown that the osmotic potential of plant tissue tends to follow changes in the osmotic potential of the root medium (2,4,6,8,23). Since the water potential of plant tissue also follows changes in the nutrient medium, the difference between these tissue potentials, the turgor pressure, usually is constant (2, 23). Bernstein (2) stated that stomatal apertures should be unchanged by these conditions. If this is true, measurements of photosynthesis and respiration could be made without reduction in CO2 supply at the surfaces of the mesophyll cells in tissue having different water potentials and osmotic potentials.Previous studies of the effects of osmotic water stress on photosynthesis and respiration have given variable results. Kling (13) found an increase in photosynthesis in plants grown in the presence of high concentrations of NaCl, but Nieman (15) has recently reported that photosynthesis was not affected by these conditions. Rather, respiration tended to be higher in the plants he studied. In the work presented here, photosynthesis and respiration as well as stomatal behavior were studied in plants subjected to various external NaCl concentrations.In this paper, the state of water in the plant will be described by thermodynamic terms (25,26) where Vw is in units of ergs cm-3, pw and p,uw are in ergs mole-', and Vw, the partial molal volume of water, is in cm3 mole-l. This is similar to previous derivations (25,26) except that partial molal quantities are used rather than partial specific quantities. Molal quantities are preferred because the number of molecules so defined remains constant regardless of temperature or type of substance. For convenience, values of water potential will be expressed in bars instead of ergs cm-3 (1 bar = 106 ergs cm-3 = 0.987 atm). Materials and MethodsCotton plants (Gossypium hirsutum L., var. Coker 100-A) were grown from seedlings in 2-liter opaque polystyrene containers fitted with black polyethylene tops. Two seedlings per container were suspended in modified Hoagland's solution, described by Johnson, et al. (12). The pH of the cultures was maintained at 5.5. Nutrient solutions were replaced every 2 weeks. The osmotic potential of the ...

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“…The latter presentation emphasizes the hyperbolic nature of this curve; i.e., it accentuates the fact that as moisture content decreased in this soil from 30 to 11 per cent. the tension increased only about one atmosphere; whereas a drop in soil moisture content from 11 Total nitrogen including nitrate was determined by a micro-modification of the method of RANKER (40). Total soluble nitrogen was extracted according to the procedure described by Clark (7), and assayed by the method of PUCHER and VICKERY (39) to the wider ranges in soil moisture content, since the correlated reduction in plant growth resulted in decreased rate of water removal.…”

Section: (With Nine Figures)mentioning

confidence: 99%

“…The observations for osmotic pressure emiiployed were those found for the surface horizon of the soil-that stratum of the soil containing the least solutes. This was considered the most valid approach since it is shown in water cultures (11,29) that the greater proportion of water taken up by roots is from the portion of the substrate having the lower osmotic pressure. The trend of moisture stresses found for the "0" salt treatmenits were niot greatly different from that of the soil moisture tension, indicating that the increase in osmotic pressure of the soil solutioni due to soil moisture depletion was not a major factor in determininog the moisture stress of this series.…”

Section: (With Nine Figures)mentioning

confidence: 99%

Growth and Biochemical Composition of Bean Plants as Conditioned by Soil Moisture Tension and Salt Concentration

1945

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There is evidence in the literature that decreasing soil moisture content is associated with increases in the osmotic pressure of the tissue fluids in both roots and tops of plants (26,27), decreases in rate of vegetative growth (1,9,15,30, 64), modifications in stomatal opening (16, 17), a depletion in starch reserves (15,35,52, 64), a decrease in apparent photosynthesis, and an increase in respiration (50). Many of these effects were noted even though the respective plants did not wilt, and notwithstanding the fact that there is considerable evidence (8, 24, 58, 62)

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Water Uptake and Root Growth as Influenced by Inequalities in the Concentration of the Substrate

Cited by 76 publications

References 6 publications

Expansion of Bean Leaves and its Suppression by Salinity

Expansion of Bean Leaves and its Suppression by Salinity

Effects of Osmotic Water Stress on Metabolic Rates of Cotton Plants with Open Stomata

Growth and Biochemical Composition of Bean Plants as Conditioned by Soil Moisture Tension and Salt Concentration

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