Nitrogen and water-use efficiency of Australian wheat varieties released between 1958 and 2007

Title 
Nitrogen and water-use efficiency of Australian wheat varieties released between 1958 and 2007 
Publication Type 
Journal Article 
Authors 
Sadras VO, Lawson C 
Year of Publication 
2013 
Volume 
46 
Journal 
European Journal of Agronomy 
Pagination 
34 - 41 
Date Published 
4/2013 
ISSN 
11610301 
URL 
http://www.sciencedirect.com/science/article/pii/S1161030112001530 
Keywords 
breeding, Evapotranspiration, Grain protein, Nitrogen harvest index, Wheat, Yield 
DOI 
10.1016/j.eja.2012.11.008 
Abstract 

We used a collection of Australian wheats released between 1958 and 2007 to probe for time trends in evapotranspiration and nitrogen uptake, and the efficiencies in the use of water and nitrogen to produce grain yield. Yield increased linearly with year of cultivar release at a rate of 18 kg ha−1 y−1; this rate aligned with the relationship between rate of genetic gain and environmental yield from breeding programs worldwide. No time trend was apparent for seasonal evapotranspiration, hence the linear increase in yield per unit evapotranspiration with year of release which was fully accounted for by yield improvement. Under our experimental conditions, yield per unit transpiration of current varieties was ∼24 kg ha−1 mm−1, highlighting the need to update the 20 kg ha−1 mm−1 ratio commonly used in agronomic benchmarking.

Yield per unit nitrogen uptake was largely unchanged as a consequence of increased nitrogen uptake that paralleled the increase in yield, and a secondary contribution of reduced grain protein concentration particularly under environmental conditions that favoured high protein. The nitrogen nutrition index, accounting for the effect of biomass on nitrogen uptake, increased linearly with year of cultivar release, hence supporting the conclusion that breeding for yield improved the nutrition status of wheat in association with an increased capacity to uptake nitrogen in equal-sized crops.

Highlights

  • Yield increased linearly with year of cultivar release between 1958 and 2007.
  • No time trend for evapotranspiration; linear increase in yield:evapotranspiration.
  • Yield per unit transpiration of current varieties was 24 kg ha−1 mm−1.
  • N uptake and N nutrition index increased linearly with year of cultivar release.
 
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