High-osmotic-potential

Seven S. cerevisiae strains were characterized relative to their resistance to sulfur dioxide (since it is a desirable feature in the fermentative yeast strains), ethanol (where tolerance is an indispensable property due to the high concentrations reached by the end of fermentation (Carrasco et al., 2001)), and osmotic stress (due to the high osmotic potential of mead at the commencement of fermentation). Pereira (2008) and Pereira et al. (2009) verified that significant differences did not exist between the strains. S. cerevisiae strains isolated from honey were similar to commercial and reference strains—all appearing to be suitable for mead production. 

Do, C.B. and Cormier, F. 1990. Accumulation of anthocyanins enhanced by a high osmotic potential in grape (Vitis vinifera L.) cell suspension. Plant Cell Rep. 9, 143-146. 

Hydrosphere. Poorly buffered against chemical changes moderate O2 availability low water availability because of high osmotic potential of seawater low ratios of biomass/unit area and photosynthesis/unit area (because of little light below the surface) low temperatures low essential elements (especially P and Fe) high NaCl. 

Saline soils are a problem for plants because the high osmotic potential of the soil solution makes it unavailable for plants. The plant has to expend so much energy to take up water that little energy is left for growth and crop yield. This is similar to the problem of organisms in marine water— all that water and none of it fit to drink. Sodium is toxic to some plants at high concentrations, but for most plants this is a relatively minor problem compared with the restricted water uptake and movement... 

Interestingly, Carnie et al. [17] point out that the linear Derjaguin approximation for constant charge density surfaces is attractive for all kH only when other case, the force becomes repulsive at very small separations, because the need for counterions to balance the extra charge leads to high osmotic stresses. Conversely, the linear Derjaguin approximation for constant potential surfaces is repulsive for all k i only when... 

Calculate the osmotic potential of an irrigation water with an EC of 10 mmhos cm-1. Explain whether the osmotic potential of this water would be too high for plants. 

Subsequent tests with velvetleaf, Kodkia, Jerusalem artichoke, and cocklebur showed that their allelopathic action altered water balance (55,94,95). Growth reductions in sorghum and soybean seedlings in nutrient solution amended with extracts from these weeds correlated with high diffusive resistances and low leaf water potentials. Stomatal closure occurred in plants treated with the more concentrated extracts. Depressions in water potential were due to a reduction in both turgor pressure and osmotic potential. A lower relative water content was also found in velvetleaf-treated plants. These impacts on water balance were not from osmotic factors. Allelochemicals from these weeds have not been thoroughly ascertained, but the present evidence shows that some contain phenolic inhibitors. Lodhi (96) reported that Kodkia contains ferulic acid, chlorogenic acid, caffeic acid, myricetin, and quercetin. As noted earlier, an effect on plant-water relationships is one mechanism associated with the action of ferulic acid. 

Osmosis is similar to diffusion in that the molecules move from a location of high chemical potential to one of low chemical potential. An osmotic pressure is generated in a colloidal solution when it is separated from its solvent by a barrier that is impermeable to the solute but is permeable to the solvent. The pure solvent will flow across the membrane, diluting the colloidal dispersion and, as the colloidal material cannot flow in the opposite direction, a pressure difference (osmotic pressure) will be created between the two compartments. Osmotic pressure is a colligative... 

The ability of yeasts to utilize sugars is not only of potential value it can also be a nuisance.25,26 Yeasts are notorious as spoilers of foods that contain a high concentration of one or more sugars, such as honey, maple syrup, sugar cane, and confectionery. The capacity of the yeasts Saccharomyces bisporus and Saccharomyces rouxii to ferment honey,27,28 which is composed of 70 to 80% of hexoses,29 is a feat of outstanding physiological interest in view of the remarkably high osmotic forces which the yeasts must withstand.30-32... 

Similarly to drought stress, sahnity imposes a water-deficit that results from the relatively high solute concentrations in the soil, but in addition it may cause ion-specific stresses resulting from altered K /Na ratios, and also may lead to a build-up in Na and d concentrations that are detrimental to plants. Plants respond to salinity using two different types of responses. Salt-sensitive plants restrict the uptake of salt and adjust their osmotic potential by the synthesis of compatible solutes (pro-hne, glycinebetaine, sugars, etc.) [19]. 

Many seeds placed in distilled water in Petri dishes under optimum conditions for germination show a triphasic pattern of water uptake as shown in Figure 4.6. Initial uptake of water in Phase I (i.e. imbibition) is a consequence of the matric forces (i/cell walls and cell contents of the seed, and this uptake occurs irrespective of whether a seed is dormant or non-dormant, viable or non-viable. Phase II is the lag period of water uptake, when the matric potential is high (less negative), as is the solute or osmotic potential Dead and dormant seeds maintain this level of hydration typical of Phase II, but unlike germinating seeds they do not enter Phase III, which is associated with visible germination. 

High water potential of the external solution will facilitate osmotic water uptake by the cells, i.e., their turgor will increase. In vivo, an increase in turgor could be achieved by malic acid accumulation in the vacuole and concomitant osmotically driven influx of water into the vacuole. 

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