Plant-water, balance

The data suggest one mechanism of allelopathic action is a disruption of plant water balance. 

Data summarizing the effects of the inhibitory weed extracts on sorghum water status was taken from the second trial in each case (Table V). All of these extract treatments had reduced sorghum growth, and all but one had some effect on plant water balance. 

Martinez-Ballesta MC, L6pez-Perez L, Muries B, Munoz-Azcarate O, Carvajal M (2009) Climate change and plant water balance. The role of aquaporins. A review. In Lichtouse E (ed) Sustainable agriculture reviews, vol 2. Springer, pp 71-89. DOI 10.1007/978-90-481-2716-0 5... 

Phenolic acids interfere with many major physiological processes of higher plants (35). These disruptions of function include an alteration of plant water balance. We found depression of leaf water potential to be an early indicator of allelochemical stress from ferulic and p-coumaric acids (42). Likewise one mechanism of allelopathic action by cultivated sunflower, velvetleaf Abutilon theophrasti Medic.), Koahia [Koahia saoparia (L.) Schrad.], and several other weeds was water stress (43-45). Since some allelochemicals interfere with plant-water relationships, it seemed logical that their action might be most critical at times when plants are under water stress from other causes. 

Rock Grinding. Until 1973, most phosphate was ground dry in roller or ball mills. In that year, Agrico, at South Pierce, Florida, converted one of its dry mills to wet slurry grinding and proved that the plant water balance could manage the rock at a 65-68 percent solids slurry. Since that time, most U.S. installations have converted to wet grinding. 

Mycorrhizas are critical to plant survival and production in arid soils. Hyphae transport water in both directions. Water from patches of moist soils to the plant is provided by fungal hyphae and rhizomorphs that explore large volumes of soil ranging outward from the canopy edge. Mycorrhizal hyphae even extend from deep roots into the bedrock to access sources of water that cannot be reached or transported in the time scales necessary to be important to plant water balance. Mycorrhizal hyphae also benefit from hydraulically lifted water from plants that have deep root systems that reach groundwater or perched water tables. 

Develop a plant water balance for average and peak operating conditions. 

Sulfuric Acid. Generally, sulfuric acid of 93—99% is used. The sulfuric values may be fed to the plant as H2SO4, oleum (20% SO ), or even SO (see Sulfuric acid and sulfur trioxide). Commonly, both H2SO4 and oleum are used. The spHt between the two is determined by water balance. AH water entering the process or produced by side reactions reacts with the SO component of the oleum ... 

Overall comparison between amine and carbonate at elevated pressures shows that the amine usually removes carbon dioxide to a lower concentration at a lower capital cost but requires more maintenance and heat. The impact of the higher heat requirement depends on the individual situation. In many appHcations, heat used for regeneration is from low temperature process gas, suitable only for boiler feed water heating or low pressure steam generation, and it may not be usefiil in the overall plant heat balance. 

The subtle interaction of air pollutants with these other stressors to plants and vegetation is the subject of ongoing research. For some plant systems, exposure to air pollutants may induce biochemical modifications which interfere with the water balance in plants, thereby reducing their ability to tolerate drought conditions. 

The first step in the analysis is to identify the target for debottlenecking the biotreatment facility. An overall water balance for the plant (Fig. 4.4) can be written as follows ... 

The very first studies with radiation crosslinked polyethylene oxide (PEO) have shown that SAH is able to substantially reduce the sensitivity of plants to water shortage [7], to promote their growth, particularly, under conditions of water deficiency [8], to improve seedling survival and the final crop [9], These results stimulated a more detailed analysis of the effects of SAH in the water balance of... 

Fig. 7. Main contributions to the water balance in soil-plant system...

Cells exposed to excessive levels of salinity have to acquire essential nutrients from a milieu with a preponderance of ions that are potentially toxic and non-essential. In this ionic environment the success of a plant cell will require intracellular tolerance and/or specific acquisition of nutrients essential for normal metabolic functioning. The cell is also exposed to an unfavourable water balance with an absolute requirement to maintain an internal osmotic regulation that favours uptake of water into the cell (Stavarek Rains, 1984 ). 

Kochi a residue levels of 2.5% significantly altered sorghum water balance, and plants grown in soil with cocklebur residues above the growth-inhibition threshold showed a trend toward elevated leaf resistances and lower water potentials than controls. A lower growth-... 

In addition to being called ET cover systems, these types of covers have also been referred to in the literature as water balance covers, alternative earthen final covers, vegetative landfill covers, soil-plant covers, and store-and-release covers. 

The ET cover cannot be tested at every landfill site so it is necessary to extrapolate the results from sites of known performance to specific landfill sites. The factors that affect the hydrologic design of ET covers encompass several scientific disciplines and there are numerous interactions between factors. As a consequence, a comprehensive computer model is needed to evaluate the ET cover for a site.48 The model should effectively incorporate soil, plant, and climate variables, and include their interactions and the resultant effect on hydrology and water balance. An important function of the model is to simulate the variability of performance in response to climate variability and to evaluate cover response to extreme events. Because the expected life of the cover is decades, possibly centuries, the model should be capable of estimating long-term performance. In addition to a complete water balance, the model should be capable of estimating long-term plant biomass production, need for fertilizer, wind and water erosion, and possible loss of primary plant nutrients from the ecosystem. 

Because borrow soils will be mixed and modified during placement, the cover soil for an ET landfill cover, as constructed, will be unique to the site. However, the soil properties may be easily described. The design process requires an evaluation of whether or not the proposed soil and plant system can achieve the goals for the cover. Numerous factors interact to influence ET cover performance. A mathematical model is needed for design that is capable of (1) evaluating the site water balance that is based on the interaction of soil, plant, and climate factors and (2) estimating the performance of an ET landfill cover during extended future time periods. 

ET is the evaporation of water from the soil surface and by plant transpiration (primarily through the stomata on the plant s leaves). ET should be carefully considered during all stages of design since it will be the largest mechanism of water removal in the water balance for an ET cover. With current knowledge, it is necessary to estimate potential evapotranspiration (PET) first and then using the PET estimate the actual evapotranspiration (AET) for the site. 

The density of soil may control the presence, absence, or density of roots found in a particular soil layer. The density of plant roots in a soil layer determines how much water plants can remove from the layer and its rate of removal. Soil compaction, in addition to inhibiting root growth, reduces soil-water-holding capacity. A model that does not consider the effect of soil density on water balance may produce significant errors in water balance estimates. 

Development of the Environmental Policy Integrated Climate (EPIC) model and its predecessor, the Erosion Productivity Impact Calculator, began in the early 1980s.69 70 The first version of EPIC was intended to evaluate the effects of wind and water erosion on plant growth and food production. More recent versions also evaluate factors important to other environmental issues. EPIC is a onedimensional model however, it can estimate lateral flow in soil layers at depth. All versions of EPIC estimate surface runoff, PET, AET, soil-water storage, and PRK below the root zone—these complete the hydrologic water balance for an ET landfill cover. 

In addition to a complete water balance, EPIC estimates plant biomass production, fertilizer use, wind and water erosion, loss of nitrogen and phosphorus from the soil, and the effect of nutrient loss from the soil on plant growth. 

UNSAT-H does not address the effects of soil density on plant growth and water balance. Disadvantages caused by the computational methods used to estimate soil water flow include the following (1) the model requires the user to choose from several submodels to solve the Richards equation this choice should be made by a person with training in advanced soil physics and (2) the model requires the input of several soil parameters that are difficult to estimate for the completed cover soil. 

Both of them require at least limited model calibration. They do not stochastically estimate daily climate data for model evaluations or long-term changes in plant nutrient status and the resulting changes in plant growth and water balance. HYDRUS and UNSAT-H would be very useful and accurate if used in research however, they are difficult to use in engineering design of ET landfill covers and provide incomplete estimates of performance. 

The microscopic approach looks at heterogeneous properties of the tissue and has been developed for plant material on the basis of plant physiology studies on the effect of osmosis on water balance and transport in growing plants. 

Owing to limitations on the water balance of the plant, a 40-50% conversion can be undertaken before a salt evaporator needs to be installed to remove excessive water. The feed brine for the membrane cellroom is taken from brine made from fresh imported salt and the weak brine is returned, combined with the diaphragm brine, restrengthened with recovered salt from the evaporators and fed to the diaphragm cells. The concentration of brine to the diaphragm cells could be weaker than normal, at around 270-280 g l-1 rather than 300-310 g l-1 to assist with the water balance. 

Repeated membrane failures during the early part of the 12-kW plant 500-hour DMMP run prevented effective control of water balance and levels of silver and organic material in the catholyte system. After laboratory-scale testing from October 11 to October 21,2001, AEA concluded that the failures resulted from foaming or pockmarks in the lattice structure of the PTFE support in the Nafion membrane and that the pockmarks formed only if the membrane came into contact with the cathode. 

Ting, I. P., and W. M. Dugger. Ozone resistance in tobacco plants A possible relationship to water balance. Atmos. Environ. 5 147-150, 1971. 

This description suggests that it is extremely difficult to measure actual evapotranspiration directly. Indeed, for individual points this can only be done using costly micrometeorological measurements in the lowest layer of the atmosphere, or with the aid of weighing lysimeters that enable evapotranspiration to be determined on a small area of plant-covered ground using the water balance... 

External excitatory and inhibitory stimuli for acceptance or rejection of food are modified by the internal condition of the insect (e.g., hunger). This modification can cause a given stimulus to produce different responses, depending upon the internal condition of the insect. After host acceptance, there are still obstacles that the insect must overcome in order to survive, grow, and reproduce. These hurdles include allelochemicals that block nutrient availability, defenses of susceptible plants, poor balance of essential nutrients, and less than optimal water content. Neonate larvae may be far more sensitive to some of these obstacles than older ones. 

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