Water uptake, by roots

Dacey, J.W.H., and Howes, B.L. (1984) Water uptake by roots control water table movement and sediment oxidation in a short Spartina marsh. Science 224, 487-489. 

Growth and water status of maize have been followed by Tardleu with either a favourable (0) or a compact (C) soil structure In the ploughed layer. Differences In DMP and In stomatal conductance (gs) were observed, and related to water uptake by roots (ratio 1). This was ascribed to the spatial arrangement of roots. The objective of this article Is to present the second term of rain water use efficiency leaf water use efficiency (WUE). 

Sharp, R.E. Davies, W.J. (1985). Root growth and water uptake by maize plants in drying soil. Journal of Experimental Botany, 36, 1441-56. 

Equation (6.20) determines the maximum degree of swelling and the maximum pore radius of a liquid-equilibrated membrane. This relation suggests that the external gas pressure over the bulk water phase, which is in direct contact with the membrane, controls membrane swelling. The observa-hon of different water uptake by vapor-equilibrated and by liquid water-equilibrated PEMs, denoted as Schroeder s paradox, is thus not paradoxical because an obvious disparity in the external conditions that control water uptake and swelling lies at its root cause. 

Hamza, M. A., and Aylmore, L. A. G. (1992). Soil solute concentration and water uptake by single lupin and radish plant roots, I Water extraction and solute accumulation. Plant Soil 145, 187—196. 

For a soil that is barely saline (EC 4 mS/cm), an osmotic pressure of about 1.5 atmospheres would result. In other words, the water in this moist soil would not be freely available to plant roots, but would be retained in a lowered free energy state equivalent to 1.5 atmospheres of water tension. This, however, is insufficient tension to seriously impede water uptake by plants. More important effects of soil salinity are likely to include particular ion toxicity effects (e.g., Na, Cl ) and nutritional imbalances (e.g., excessive Na" or uptake relative to Ca " and Mg ). 

The rate of transfer of solutes between soil and overlying water column and from one physical or chemical state to another is defined as flux. The dimensions of flux are M T where M is the mass of material transferred by flux, L is the distance or length, and T is the time. The processes associated with flux are advection, diffusion, and dispersion. Diffusive and advective flux between soil and overlying water and elemental uptake by rooted wetland vegetation are the major transport... 

Lyu S-W, Blum U (1990) Effects of fendic acid, an adelopathic compound, on net P, K, and water uptake by cucumber seeddngs in a split-root system. J Chem Ecol 16 2429-2439 Lyu S-W, Blum U, Gerig TM, O Brien TE (1990) Effects of mixtures of phenolic acids on phosphorus uptake by cucumber seedlings. J Chem Ecol 16 2559-2567 MaMno T, Takahashi Y, Sakurai Y, Nanzyo M (1996) Infiuence of soil chemical properties on adsorption and oxidation of phenodc adds in sod suspension. Soil Sci Plant Nutr 42 867-879... 

Sulfur and/or nitrogen derived pollutants affect red spruce through soil mediated processes involving a) direct toxicity to roots by mobilized metals in the soil, b) inhibition of nutrient uptake by roots due to the mobilization of metals, and c) leaching of nutrients from the rooting zone by acidic deposition resulting in altered tree water and nutrient balance. 

In soil, the stronger uptake by roots of lipophilic compounds from the soil water is offset by the reduced availability due to the sorption of lipophilic chemicals onto soil organic matter as discussed above. 

Figure 9.5. Relationship between the translocation of chemicals to shoots following uptake by roots (expressed as the transpiration stream concentration factor) and the octan-l-ol/water partition coefficients (as log K y,) (a) in barley O, O-methylcarbamoyloximes x, substituted phenylureas (b) literature values for several herbicides and fungicides in different plant species. (Reproduced from Ref. 34.)...

The main use of dinitroanilines is to control annual weeds, particularly grasses, following preemergence application to soil. Uptake by roots and germinating shoots may be predominantly via the vapor phase or via the aqueous phase depending upon the compound the resulting inhibition of mitosis is particularly noticeable from the abnormal features of treated roots. The less lipophilic compounds (dinitramine, nitralin, and oryzalin) are taken up from soil via the water phase and are then translocated to shoots to a small extent. However, such movement does not appear to be necessary for the phytotoxic action of these compounds. 

Shone, M.G.T. Flood, A.V. (1983). Effects of periods of localised water stress on subsequent nutrient uptake by barley roots and their adaptation by osmotic adjustment. New Phytologist, 94, 561-72. 

E. K. S. Nambiar, The uptake of zinc-65 by roots in relation to soil water content and root growth. Aust J. Soil Re.s. 14 61 (1976). 

---