, Volume 44, Issue 4, pp 536–541 | Cite as

Awn contribution to gas exchanges of barley ears

  • Q.Z. Jiang
  • D. Roche
  • S. Durham
  • D. Hole
Original Papers


The effects of awn removal on ear gas exchange in four barley lines (Morex, Harrington, Steptoe, and TR306) were studied under a controlled environment using a Before-After Control-Impact Paired (BACIP) experimental design. From ear emergence to grain maturity, plants were grown in pots at either 60 or 90 % of soil water holding capacity. Gas-exchange measurements of ears were made 9 and 10 d after anthesis (DAA). On 11 DAA, awn removal was performed on half of the ears in each pot, followed by measurements on both intact and de-awned ears on 12 and 13 DAA. Net photosynthetic (P N) and transpiration (E) rates decreased significantly with awn removal, but dark respiration (R D) rate was not affected. We estimated for each ear a temperature-adjusted respiration rate (R a) from R D. When we corrected P N with R a, we found that rates of spikelet photosynthesis were largely underestimated. Moderate water stress had minimal effect on gas exchange of bracts and awns of the barley ear. Barley lines did not differ for any individual gas-exchange parameter.

Additional key words

BACIP design Hordeum net photosynthetic rate respiration rate transpiration 



Before-After Control-Impact Paired


days after anthesis


transpiration rate


instantaneous water-use efficiency


net photosynthetic rate


gross photosynthetic rate


photosynthetic photon flux density


temperature-adjusted respiration rate


dark respiration rate


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  1. Amthor, J.S.: Respiration and Crop Productivity.-Springer-Verlag, New York-Berlin-Heidelberg-London-Paris-Tokyo 1989.Google Scholar
  2. Araus, J.L., Brown, H.R., Febrero, A., Bort, J., Serret, M.D.: Ear photosynthesis, carbon isotope discrimination and the contribution of respiratory CO2 to differences in grain mass in durum wheat.-Plant Cell Environ. 16: 383–392, 1993.CrossRefGoogle Scholar
  3. Biscoe, P.V., Littleton, E.J., Scott, R.K.: Stomatal control of gas exchange in barley awns.-Ann. appl. Biol. 75: 285–297, 1973.CrossRefGoogle Scholar
  4. Blum, A.: Photosynthesis and transpiration in leaves and ears of wheat and barley varieties.-J. exp. Bot. 36: 432–440, 1985.Google Scholar
  5. Bort, J., Brown, R.H., Araus, J.L.: Refixation of respiratory CO2 in the ears of C3 cereals.-J. exp. Bot. 47: 1567–1575, 1996.Google Scholar
  6. Bort, J., Febrero, A., Amaro, T., Araus, J.L.: Role of awns in ear water use efficiency and grain weight in barley.-Agronomie 14: 133–139, 1994.Google Scholar
  7. Caemmerer, S. von, Farquhar, G.D.: Some relationships between the biochemistry of photosynthesis and the gas exchanges of leaves.-Planta 153: 376–387, 1981.CrossRefGoogle Scholar
  8. Condon, A.G., Richards, R.A., Rebetzke, G.J., Farquhar, G.D.: Improving intrinsic water-use efficiency and crop yield.-Crop Sci. 42: 122–131, 2002.PubMedCrossRefGoogle Scholar
  9. Derera, N.F., Stoy, V.: Varietal differences in photosynthetic efficiency of the awns.-In: Sears, E.R., Sears, L.M.S. (ed.): Proceedings of the Fourth International Wheat Genetics Symposium. Biochemical and Physiological Genetics. Pp. 791–796. Columbia 1973.Google Scholar
  10. Hochhalter, M., Horsley, R.D.: Barley: Agronomy.-In: Wrigley, C., Corke, H., Walker, C.E. (ed.): Encyclopedia of Grain Science. Pp. 38–46. Elsevier, Oxford 2004.Google Scholar
  11. Johnson, R.R., Frey, N.M., Moss, D.N.: Effect of water stress on photosynthesis and transpiration of flag leaves and spikes of barley and wheat.-Crop Sci. 14: 728–731, 1974.CrossRefGoogle Scholar
  12. Johnson, R.R., Willmer, C.M., Moss, D.N.: Role of awns in photosynthesis, respiration, and transpiration of barley spikes.-Crop Sci. 15: 217–221, 1975.CrossRefGoogle Scholar
  13. Kjack, J.L., Witters, R.E.: Physiological activity of awns in isolines of Atlas barley.-Crop Sci. 14: 243–248, 1974.Google Scholar
  14. Knoppik, D., Selinger, H., Ziegler-Jöns, A.: Differences between the flag leaf and the ear of a spring wheat cultivar (Triticum aestivum cv. Arkas) with respect to the CO2 response of assimilation, respiration and stomatal conductance.-Physiol. Plant. 68: 451–457, 1986.CrossRefGoogle Scholar
  15. Paluska, M.M.: Effect of flag leaf and awn removal on seed weight of Arivat barley.-Arizona-Nevada Acad. Sci. J. 16: 22–23, 1981.Google Scholar
  16. Reid, D.A., Wiebe, G.A.: Taxonomy, botany, classification and world collection.-In: Barley: Origin, Botany, Culture, Winter-Hardiness, Genetics, Utilization, Pests. Agriculture Handbook No. 338. Pp. 61–84. Agricultural Research Service. U.S. Department of Agriculture, Washington 1968.Google Scholar
  17. Smith, E.: BACI design.-In: El-Shaarawi, A.H., Piegorsch, W.W. (ed.): Encyclopedia of Environmetrics. Pp. 141–148. John Wiley & Sons, Chichester 2002.Google Scholar
  18. Tambussi, E.A., Nogués, S., Araus, J.L.: Ear of durum wheat under water stress; water relations and photosynthetic metabolism.-Planta 221: 446–458, 2005.PubMedCrossRefGoogle Scholar
  19. Thorne, G.N.: Varietal differences in photosynthesis of ears and leaves of barley.-Ann. Bot. 27: 155–174, 1963.Google Scholar
  20. Wechsung, F., Garcia, R.L., Wall, G.W., Kartschall, T., Kimball, B.A., Michaelis, P., Pinter, P.J., Jr., Wechsung, G., Grossman-Clarke, S., Lamorte, R.L., Adamsen, F.J., Leavitt, S.W., Thompson, T.L., Matthias, A.D., Brooks, T.J.: Photosynthesis and conductance of spring wheat ears: field response to free-air CO2 enrichment and limitations in water and nitrogen supply.-Plant Cell Environ. 23: 917–930, 2000.CrossRefGoogle Scholar
  21. Wilson, I.D., Barker, G.L.A., Beswick, R.W., Shepher, S.K., Lu, C., Coghill, J.A., Edwards, D., Owen, P., Lyons, R., Parker, J.S., Lenton, J.R., Holdsworth, M.J., Shewry, P.R., Edwards, K.J.: A transcriptomics resource for wheat functional genomics.-Plant Biotech. J. 2: 495–506, 2004.CrossRefGoogle Scholar
  22. Ziegler-Jöns, A.: Gas exchange of ears of cereals in response to carbon dioxide and light. I. Relative contributions of parts of the ears of wheat, oat, and barley to the gas exchange of the whole organ.-Planta 178: 84–91, 1989a.CrossRefGoogle Scholar
  23. Ziegler-Jöns, A.: Gas exchange of ears of cereals in response to carbon dioxide and light. II. Occurrence of a C3-C4 intermediate type of photosynthesis.-Planta 178: 164–175, 1989b.CrossRefGoogle Scholar

Copyright information

© Institute of Experimental Botany, ASCR 2006

Authors and Affiliations

  1. 1.Department of Plants, Soils and BiometeorologyUtah State UniversityLoganUSA
  2. 2.Ecology CenterUtah State UniversityLoganUSA

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