Transpiration rate

Assume that the entering material is rapidly mixed so that the composition is always uniform in the radial direction. The transpiration rate per unit length of tube is = q(z) with units of m /s. Component A has concentration Utrans = o-transi/) in the transpired stream. The component balance, Equation (3.4), now becomes... 

Suppose an inert material is transpired into a tubular reactor in an attempt to achieve isothermal operation. Suppose the transpiration rate q is independent of and that qL = Qtrms- Assume all fluid densities to be constant and equal. Find the fraction unreacted for a first-order reaction. Express your final answer as a function of the two dimensionless parameters, QtranslQin and kVIQm where k is the rate constant and... 

The amount of growth occurring when rainfall is limited depends on the ratio of assimilation rate to transpiration rate. In a leaf the instantaneous transpiration efficiency, A E, is given approximately by... 

Salt damage is due to the product of xylem concentration and transpiration rate over the life of the leaf. There are several pathways for salt entry into the root. In spite of many reports in the literature of correlative associations between the lipid analyses of relatively crude root membrane preparations and salt resistance (see Kuiper, 1985), we have not been able... 

All leafy horticultural commodities show high transpiration rates due to their large surface areas and this poses the additional problem of accelerating senescence. Therefore, a great challenge of most processes has been the maintenance of the original food color along with other characteristics perceived as quality issues by consumers. 

Mature phreatophyte trees (poplar, willow, cottonwood, aspen, ash, alder, eucalyptus, mesquite, bald cypress, birch, and river cedar) typically can transpire 3700 to 6167 m3 (3 to 5 acre-ft) of water per year. This is equivalent to about 2 to 3.8m3 (600 to 1000 gal) of water per tree per year for a mature species planted at a density of 600 trees per hectare (1500 trees per acre). Transpiration rates in the first two years would be somewhat less, about 0.75 m3 per tree per year (200 gal per tree per year), and hardwood trees would transpire about half the water of a phreatophyte. Two meters of water per year is a practical maximum for transpiration in a system with complete canopy coverage (a theoretical maximum would be 4 m/yr based on the solar energy supplied at latitude 40°N on a clear day). 

The effect of zearalenone on crop development may be connected to its influence on the status and functioning of the photosynthetic apparatus (Koscielniak et al. 2008). The after-effects of zearalenone on the growth of soybean and wheat plants, net photosynthesis and transpiration rates, stomatal conductance, photochemical efficiency of photosystem 2 and on final seeds yield were determined. Modifications in leaf area were more pronounced in soybean than in wheat, and this tendency increases in successive developmental phases. The net photosynthesis was stimulated during the juvenile phase and during that of the final one by about 13.6% (average) in soybean plants. Stimulation of transpiration was also observed after... 

Plant water status is affected by environmental pollution and consequently influences plant function at every level of biological organisation. It can be characterized by measurements of the relative water content (RWC), the water deficit, the water potential ( P ) and the osmotic potential ( Fq), along with transpiration rate and stomatal resistance. Since for the latter four parameters, tissue samples are removed from the plant, they are usually determined in the end of an experiment. If several sampling times are needed, then additional plants/replicates must be included. 

Transpiration rate and stomatal resistance are the most commonly measured plant gas exchange parameters using IRGA. Their behaviour in A. thaliana plants exposed to heavy metal ion stress is demonstrated in Figure 2 B and C. 

This was not found to be the case for the nitrogen oxides. Transpiration rates were not depressed significantly by exposures to NO or NO2 that caused marked depressions in the CO2 uptake rates. The nitrogen oxides appeared to inhibit CO2 uptake rates by affecting the biochemical fixation of C02 ... 

Figure 17.11 Neil Yorio at NASA s Kennedy Space Center taking leaf porometer measurements with potatoes to monitor stomatal conductance and transpiration rates. When measurements were taken at 400 ppm CO2, a mask was worn to removed exhaled breath from the chamber to avoid elevating the CO2 concentration.

Chuang Y.-L. Oren R. Bertozzi A.L. Phillips N. and Katul G.G. (2006). The porous media model for the hydraulic system of a conifer tree Linking sap flux data to transpiration rate. Ecological Modelling, 191(3-4), 447-468. 

Leaf transpiration rates closely parallel photosynthetic rates over a range of light intensities (i.e., 400 to 1200 pmol m 2 sec 1) (Soja and Haunold, 1991). Water use efficiency, therefore, remains rather stable relative to photosynthesis until the light intensity drops below 300 pEm-2-sec 1. Here water use efficiency decreases sharply, with transpiration being higher relative to photosynthesis. 

Meiri, A. and A. Poljakoff-Mayber. 1970. Effect of various alinity regimes on growth. Leaf expansion and transpiration rate of bean plants. Soil Sci. 109 26-34. 

We will represent the flux density of water vapor diffusing out of a leaf by the transpiration rate. If we multiply this amount of water leaving per unit time and per unit leaf area, Jw> by the energy necessary to evaporate a unit amount of water at the temperature of the leaf, //vap, we obtain the heat flux density accompanying transpiration, jJji... 

D. If the net radiation balance for the leaf is 300 W m-2, what is the transpiration rate such that the leaf temperature remains constant ... 

Values were determined using quantities in Appendices I and II. To convert from one set to another, a quantity expressed in the units in the left column should be multiplied by the factor in the column of the desired units. Bor example, a transpiration rate of 3.0 gH20 dm-2 hour-1 equals (3.0)(1.542) or4.6 mmol m-2 s-1. 

---