Crop Science Grow Your Career with CSSA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published in Crop Sci 15:217-221 (1975)
© 1975 Crop Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Johnson, R. R.
Right arrow Articles by Moss, D. N.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Johnson, R. R.
Right arrow Articles by Moss, D. N.
Agricola
Right arrow Articles by Johnson, R. R.
Right arrow Articles by Moss, D. N.

Role of Awns in Photosynthesis, Respiration, and Transpiration of Barley Spikes1

Richard R. Johnson, Colin M. Willmer and Dale N. Moss2

To assess the role of awns in photosynthesis, respiration, and transpiration, the water vapor and Co2-exchange rates were measured on spikes of barley (Hordeum vulgare L.) genotypes ranging from awnless to those having several meters of awn/spike. The plants were grown in large pots in the field and brought into the laboratory for measurement. An increased amount of awn tissue resulted in greater rates of net photosynthesis, dark respiration, and transpiration per spike. The awns of all genotypes remained photosynthetically active throughout grain filling, although some reached maximal activity soon after emerging from the flag leaf sheath, while others had peak rates only a few days before maturity.

The total length of awn tissue of each spike remained constant throughout the grain-filling period, but the awn dry weight of the full-awned genotypes increased during that period. Awn dry weight, rather than awn number or awn length, best described the amount of photosynthetic tissue present. The genotype which had the dense spike character had a lower photosynthetic efficiency (mg CO2 fixed per g awn dry weight) than did the other genotypes. Removing the top two leaves on each culm to reduce the assimilate supply to the grain increased synthetic rates of the spikes slightly, but not sufficiently to compensate for the leaf area removed.

Key Words: Hordeum vulgare L. • Morphology • Defoliation

1 Contribution of the Dept. of Agron. and Plant Genet., University of Minnesota, St. Paul, MN 55101. Minn. Agr. Exp. Stn. scientific journal no. 8420. This work was supported partially by the USDA contract 12-14-10010929(34).

2 Former graduate assistant (now assistant professor, Dept. of Agron., U. of Ill., Urbana, IL 61801); former research fellow (now research fellow, Dept. of Biol., U. of Stifling, Stifling, FK9 4LA, Scotland); and professor, respectively.

Received for publication August 11, 1973.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Agronomy Journal Vadose Zone Journal
Journal of Natural Resources
and Life Sciences Education		 Soil Science Society of America Journal
Journal of Plant Registrations Journal of
Environmental Quality		 The Plant Genome
Copyright © 1975 by the Crop Science Society of America.