Transpiration efficiency: new insights into an old story uri icon


  • Producing more food per unit of water has never been as important as it is at present, and the demand for water byeconomic sectors other than agriculture will necessarily put a great deal of pressure on a dwindling resource, leadingto a call for increases in the productivity of water in agriculture. This topic has been given high priority in the researchagenda for the last 30 years, but with the exception of a few specific cases, such as water-use-efficient wheat inAustralia, breeding crops for water-use efficiency has yet to be accomplished. Here, we review the efforts to harnesstranspiration efficiency (TE); that is, the genetic component of water-use efficiency. As TE is difficult to measure,especially in the field, evaluations of TE have relied mostly on surrogate traits, although this has most likely resulted inover-dependence on the surrogates. A new lysimetric method for assessing TE gravimetrically throughout the entirecropping cycle has revealed high genetic variation in different cereals and legumes. Across species, water regimes,and a wide range of genotypes, this method has clearly established an absence of relationships between TE and totalwater use, which dismisses previous claims that high TE may lead to a lower production potential. More excitingly,a tight link has been found between these large differences in TE in several crops and attributes of plants that makethem restrict water losses under high vapour-pressure deficits. This trait provides new insight into the genetics of TE,especially from the perspective of plant hydraulics, probably with close involvement of aquaporins, and opens newpossibilities for achieving genetic gains via breeding focused on this trait. Last but not least, small amounts of waterused in specific periods of the crop cycle, such as during grain filling, may be critical. We assessed the efficiency ofwater use at these critical stages

publication date

  • 2014