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SUMMARY:Crop improvement and evaluation of water use efficiency by wheat: 
 an integrated approach using stable isotopes - Celestin Ukozehasi
DTSTART:20130118T130000Z
DTEND:20130118T133000Z
UID:TALK42759@talks.cam.ac.uk
CONTACT:24938
DESCRIPTION:Plant breeding for improved environmental stress tolerance has
  primarily relied upon traditional selection methods\, augmented by marker
  assisted selection and some high-throughput physiological methodologies. 
  Of the latter\, stable isotopes of carbon (13C/12C) and oxygen (18O/16O) 
 offer insights into the balance between stomatal regulation of gas exchang
 e and overall leaf water balance\, with organic material providing an inte
 grated history of leaf performance. Recently\, two varieties of wheat have
  been brought to the market as a result of using selection for drought tol
 erance and yield stability informed by carbon isotopes (CSIRO: Drysdale an
 d Rees)\, and using δ13C and δ18O in combination offers additional insig
 hts into carbon and water balance of leaves under similar environmental co
 nditions.  Other more labour intensive methods can be used to provide a sn
 apshot of short-term limitations\, such as photosynthetic gas exchange and
  water relations\, and this study set out to explore how well these proxie
 s relate to more long-term isotopic markers\, and as compared to leaf anat
 omical traits.\n\nIn this preliminary programme\, photosynthetic and hydra
 ulic characteristics\, leaf morphology\, flowering and yield measurements 
 were collected on 23 recombinant inbred lines of Rht cultivars grown in th
 e field at the National Institute of Agricultural Botany. Having ranked a 
 number of traits according to likely physiological associations\, there wa
 s a good correlation between carbon isotope composition (∆13C) and insta
 ntaneous water use efficiency (WUEi)\, and that Specific Leaf Area (cm² g
 ⁻¹) could be used as surrogate measure of ∆13C. There were also inter
 esting associations between leaf hydraulic supply and stomatally-led evapo
 rative demand.  We also found that there might be a trade-off for selectin
 g WUEi\, earliness of flowering and yield. The research will continue by e
 valuating resource dynamics in the semi-dwarf phenotypes (RhtNILs in a Mer
 cia background)\, comparing carbon and nitrogen allocation and water use a
 s a function of straw shortening. These methods will also be used to evalu
 ate the performance of Rwandan wheat cultivars under field conditions. 
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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