1. Does it really support plant production under limited water supply?.
WUE
Does it really support plant production under limited water supply?

2. Always wait a few seconds before you move to the next slide
Important Note:
Always wait a few seconds before you move to the next slide

4. Tuskegee University, Alabama, USA
12/9/2018
Developing ‘Less Thirsty’ Crops: How biotech can help us get more crop per drop
C. S. Prakash
Tuskegee University, Alabama, USA

5. Remember
WUE was developed as a tool to asses irrigation efficiency and to prevent wastefull water use.

6. (A study with drought susceptible and resistant varieties of wheat)
Control
Stress
<Available water 5 10 15 20 25
BIOMASS (g)
Susceptible
Resistant
The drought resistant plant used more water and produced more while the less productive susceptible plant saved water and thus had high WUE
0.0020
0.0025
0.0030
0.0035
0.0040
0.0045
0.0050
WUE
Susceptible
Resistant
2000
4000
6000
8000
WATER-USE (g)
Susceptible
Resistant

7. Carbon isotope discrimination (delta)
- A biochemical marker for plant WUE
Farquhar G.M. Masle J. Hubrick M. von Caemmere S. Terashima I. Current Topics in Plant Biochem.& Physiol. 6: , 1987.
This marker enabled to performe least 150 studies on WUE in relations crop breeding, by One typical example is below:)
The effect of selection for WUE (delta) and on productivity and water- use of crested wheatgrass under drought stress
Read et al., Crop Sci.32:168, 1992

8. Carbon isotope discrimination (CID) and wheat canopy temperature as a marker for drought resistance
Low WUE
Wheat
High WUE
Susceptible
Resistant
From Rebetzke et al. (CSIRO Presentation)

9. Drought resistant genotypes have low WUE
Authors
Journal
Crop
Morgan et al., 1993
Crop Sci.33:
Wheat
Ngugi et al., 1994
Euphytica 73:
Cowpea
Price et al., 2002
J.Exp.Bot.53:
Rice
Solomon and Labuschagne, 2004
Euphytica 136:69-79
Wheat durum
Pinheiro et al., 2005
Ann.Bot.96:
Coffee tree
Coffee
Monneveux et al., 2006
Plant Sci.170:
Monneveux et al., 2007
Plant Sci.173:
Maize
Sánchez-Gómez et al., 2010
Environ.Exp.Bot.70:
Pinus pinea L.
Pozo del et al., 2012
Ann.Appl.Biol.160:157–167
Barley
Kashiwagi et al., 2013
Field Crops Res.144:88–95
Chickpea
… and more

10. Genetic Improvement of Water-use and not WUE drove biomass and yield improvement in wheat.
(Mean values for wheat grown in NW Mexico, 2010 and 2011)
Pask, AJD and MP Reynolds Breeding for yield potential has increased deep water extraction capacity in irrigated wheat. Crop Sci. 53:2090–2104 (2013)

12. Most genetic variations in WUE are driven by variations in WU and not by variations in productivity
Selection for high WUE is a proxy for low WU and it generally resulted in early flowering plants of reduced growth, smaller plant size and lower yield potential.
Under conditions of limited stored soil moisture conditions selection for high WUE (lower water-use at midseason) may result in better yield because this might avoid a terminal desiccation at grain filling.
Under well watered conditions selection for high WUE can result in higher potential yield
Drought resistant varieties developed under classical selection programs tend to express low WUE.

13. “… genotypes able to sustain a higher water use and stomatal conductance were the most productive and best adapted “ (Abstract)

14. To download the pdf look for this title at Plantstress/Breeding/drought

15. “What is the difference between WUE and Water Productivity?”
Answer:
WUE is a mathematically defined ratio whereas Water Use (or transpiration) and Productivity (or assimilation) are both quantifiable.
Water productivity is a vague, undefined and an unquantified term which is used loosely in discussions about water and dryland farming .