What is water use efficiency? How Water use efficiency of plants can be measured? How a particular soil moisture condition can be maintained? How yield efficiency of under drought stress can be measured.
water use efficiency can be estimated by calculating amount of water consumed per unit of co2. you have to firstly have the rate of photosynthesis per unit of time and at the same time amount of water plant consumed, then you can explain WUE by the amount of water used/amount of CO2.
Of course there could be other methods to express this variable, for example you can interpret WUE by the amount of water consumed to produce a unit weight of biomass..
if it is not enough, inform me for more..
Water use efficiency (WUE) is the ability of the crop to produce biomass per unit of water transpired. Water use efficiency was considered as an important component of adaptation to water stress, where the identification of genotypes with high yield and high WUE is important, especially for the developing countries. Improving the efficiency of water use in agriculture is associated with increasing the fraction of the available water resources that is transpired, because of the unavoidable association between yield and water use.
Water use efficiency was calculated by dividing the grain yield (ton ha-1) or the biomass yield (ton ha-1) by the total amount of water added (gallon). Therefore, water use efficiency for grain yield (WUEG) was calculated from grain yield and water use efficiency for biomass yield (WUEB) was estimated from biomass yield according to Stanhill (1987) as following:
WUEG = Grain yield (ton) / Total water used (gallon)
WUEB = Biomass yield (ton) / Total water used (gallon)
http://www.jspb.ru/issues/2013/N2/JSPB_2013_2_21-34.html
http://www.jspb.ru/issues/2013/N2/JSPB_2013_2_21-34.html
Water use efficiency of plants, also called transpiration efficiency (TE) refers to the amount of water transpired per unit biomass produced by the plant. It is easy to measure for a particular situation if plants are grown in pots and direct evaporation from the pot minimized, just measuring pot weight, assuming that changes are mainly due to transpiration ( a good assumption) and harvesting biomass. Then you will have Biomass/water transpired or TE. The TE is highly influenced by envirionmental variables but particularly by vapor pressure deficit in the atmosphere (vpd) and by CO2 concentration. To compare results with other determinations of TE you can normalize your values by vpd and CO2 concentration in the atmosphere.
As you can see from the previous paragraph you do not need to maintain a constant soil water content to measure TE since what you are really interested in is water loss by transpiration. Of course you can measure TE under well irrigated conditions and under droughted conditions.
If you have a crop under different watering regime you can also estimate TE by plotting biomass or yield in the Y axis and ET (evapotranspiration) in the X axis. A linear plot is produced whose slope is the TE and the intercept in the X axis the soil evaporation. It is worth keeping in mind that TE is similar for species of a given carboxilation group (C3 or C4) even though differences within species have been reported.
Not wanting to confuse you too much but from my understanding a lot of the comments here are describing WATER PRODUCTIVITY (amount of biomass produced per water transpired (T)) rather than WUE (biomass produced for total water consumed (ET) in producing it). it is difficult to separate Evaporation and transpiration in an open system (field) but things like drainage and runoff can be quantified. For further reading please see the following attached document
hi
a new method for measuring WUE is using of photosynthesis meter(LCI). this instrument measured photosynthesis and transpiration.
you can obtain WUE with divided photosynthesis on transpiration amount.(Ph/E)
good luck
There is a wide meaning of WUE. The efficiency is the slope of a curve relating photosynthesis (Y) to transpiration. Provided climate is stable we can assume that vapour pressure deficit of leaves to air and Ci, the internal CO2 level are in homeostatis around an equilibrium and then the 13C discrimination of leaf cellulose would measure WUE in genotype selection. One should remember that the slope of a curve is not a constant and that changing nutrition or time of the day or season also WUE changes. The water quotient is much simpler and requires to weight in lysimeters or pots the amount of water used like when during a season plants are removed and dry weight obtained at increasing dates. Water use in the field has a lot of names but one should take in to account also water losses due to plant absence when they are not yet planted and humidity soil profiles; this value often is an harvest index scaled to mean season water availability. The timing of water supplies are critical in such models, but DSSAT or CROPGRO have a lot of case studies. S. Ceccarelli when at FAO ICARDA produced a theoretical framework of water use under drounght and frequently resistant types are better but under water shortage, whereas the most productive are better under ample water supply, but it is really a game.
In any case is better not divide metric (?) tons by gallons. Please use the metric system.
how to convert WUE of mole basis to mass basis? formula and procedure? please any one can help me?
WUE is usually a slope of molar fluxes coming from gas exchange measurements; some call it intrinsic water use efficiency and this is a variant using stomatal conductance in place of transpiration. Transpiration can be put in carbon equivalence by dividing its rate by 1.6. When we hearvest a crop or cut wood we can measure the water quotient as the ratio of dry matter to input water. If you like irrigation quotient you limit the input to added water, as it is very difficult to know how much water was taken up by a plant in the field. At end you will have a dry mass in g divided by a mass in water, usually at a one thousand ratio scale like Kg. Molar ratio is another way of measuring mass but you should know by elemental analysis the % of C, N or S in your dry sample, then correct dry weight in Element % and divide by 12 for C 14 for N and of course 18 for water. WUE is related to quotients by a quite long path, that requires measurements of respiration and partitioning
How to calculate that a plant A is more tolerant than plant B by putting the values of the WUE from photosynthesis and transpiration.
Determination of water use efficiency (WUE):
Water use efficiency was calculated by dividing the grain yield (ton ha-1) or the biomass yield (ton ha-1) by the total amount of water added (gallon). Therefore, water use efficiency for grain yield (WUEG) was calculated from grain yield and water use efficiency for biomass yield (WUEB) was estimated from biomass yield according to Stanhill (1987) as following:
WUEG = Grain yield (ton) / Total water used (gallon)
WUEB = Biomass yield (ton) / Total water used (gallon)
Is there any difference between actual water availability and effective water
Generally water use efficiency are determined for irrigated crop which depend on the purpose and field of water management. It should be cleared that water use efficiency of crop whether should be estimated for on farm or on station.
Water use efficiency at experimental level (on station)
Crop water use efficiency is not identical, it varies depending on crop type, crop variety, season, agro meteorological parameters, and soil characteristics.
To determine crop water use efficiency from field experimentation at first water requirement of the crops should be determined for the loss of water for land preparation, crop consumptive use, evaporation and seepage and percolation.
Then apply the different amount of water for different treatment of irrigation and soil type.
Use equation 1 and 2 to determine water use efficiency.
Water use efficiency for crop grain
= (grain yield/ water applied at different level of requirement) expressed in kg/m3 or kg/ha/mm (1)
Water use efficiency for crop biomass = (Total Biomass / water applied at different level of requirement) (2)
Water use efficiency at farm level (on farm)
To determine water use efficiency at farm level at first irrigation efficiency from storage efficiency, application efficiency and distribution efficiency should be measured depending on field situation and condition. From the ratio of yield and water use over the season the water use efficiency can be measured.
Hi all,
I have a great pleasure to read this discussion, and I have a question on the Total water used.
So, if someone can explain me, what is the total water used? it's by plant or what?
Thank you in advance
Total water used by plant represents the water consumption and it is estimated by the total water loss through evapo-transpiration (ET). The water use efficiency is the ration between dry matter production of a plant (the output) divided by evapotranspiration. Therefore the equation for Water use efficiency (WUE) will be written as: Dry matter production (kg/ha) / ET (in mm).
Hello dear Kumar Rai,
As physiologicall, we can determine WUE by using this equation: CO2 assimilation rate/Transpiration rate (WUE=A/E).
please, if I measure WUEas follow
total biomass by gram divided by weight of water between first time of experiment and the end of it ) , what is unit should I write with the result and is this wright way to account WUS. thanks in advance
Water use efficiency (WUE) is generally defined as marketable yield/ET, but economists and farmers are most concerned about the yield per unit of irrigation water applied. Thus, the WUE was calculated as yield (kg/ha) divided by irrigation water (m3/ha).
In physiological studies The Water Use Efficiency was Net CO2 assimilation (Pn) / Transpiration (E)
In Agronomical studies, it was the biomass of crops by hectar / total quantities of water irrigation used
Which WUE? There are two WUE as far as i know 1. photosynthetic WUE and 2. productivity.
Please, anyone who has a papers about water use efficiency kindly send in to my email address [email protected]... I m working in the area just need more info about the concept.
Your response will be highly appreciated
Interesting discussion; even today there is no consensus reached on the topic of water use efficiency (WUE) and water productivity. WUE is the ratio of yield (differing on a crop; for leafy vegetables it is the aboveground biomass, whereas for grains it it the grain yield plus the biomass) per amount of water applied (irrigation). Water productivity, is the ratio of yield per actual evaporation (ET)- in the case of water productivity, it should actually be the beneficial use of water (T) only but because it is difficult to separate T for E, then ET is used. I know there are a lot of opinions and ideas emanating from different disciplines. This is the case for Agricultural water management. Please read the following article; Van Halsema and Vincent, 2012.
Efficiency and productivity terms for water management: A matter of contextual relativism versus general absolutism. Article Efficiency and productivity terms for water management: A ma...
Melvin, I do understand the concepts much better this time around and I just wanna say thank you for the information you shared with me. Much more appreciated hope you and your family that side of your world doing well bro.
there are three definitions of water use efficiency depending on who is using it.
Engineering definition: Yield of the farm/water released from the source.
Botanical definition: Total plant biomass/water uptake by the plant.
Horticultural definition: Total yield/water uptake by the plant
I agree with Youssef Sassine. Please read the following that may help you.
Article Independent effect of water content in rockwool® on water us...
The water use efficiency of the plants can be estimated by measuring the field capacity of the soil culture and its moisture content
Water use efficiency (or transpiration efficiency) describes the intrinsic
trade-off between carbon fixation and water loss that occurs in dry land plants
because water evaporates from the interstitial tissues of leaves whenever stomata open for CO2acquisition. for all questions you can refer to the next link:
(PDF) Water Use Efficiency. Available from: https://www.researchgate.net/publication/268872656_Water_Use_Efficiency .
Amazing discussion indeed, Thank you so very much friends for your insights!
Kind regards.
I would like to add that the definition can be somewhat tuned according to the subject area (e.g. agronomy & engineering).
I found van Halsema and Vincent (2012, doi:10.1016/j.agwat.2011.05.016) and Giordano et al (2019; doi:10.1080/07900627.2019.1576508) and http://www.fao.org/3/w3094e/w3094e04.htm very useful.
Best
Interesting discussion;
Water use efficiency is a broad concept that can be defined in many ways, which depend on the purpose. In irrigated agriculture defined as yield per irrigation water applied. Also calculated as yield/ETa. At physiological level WUE is CO2 assimilated/transpiration.
Often there is confusion between Water Productivity and Water Use Efficiency
Water Productivity (WP) is the yield produced per unit of water applied in the entire season. In this case, the total/gross water used is considered
WP (kg/m3) = Yield (kg)/Water Applied (m3)
Water Use Efficiency (WUE) is the ratio of dry matter yield (kg ha-1) to actual evapotranspiration (mm)
WUE (kg/ha/mm)
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