HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Van Bavel, C. H. M. Articles by Ehrler, W. L. Search for Related Content PubMed Articles by Van Bavel, C. H. M. Articles by Ehrler, W. L. Agricola Articles by Van Bavel, C. H. M. Articles by Ehrler, W. L.

Water Loss from a Sorghum Field and Stomatal Control¹

Measurements of temperature and diffusion resistance of leaves and of micrometeorological factors in a wellwatered sorghum field during June in central Arizona show that the stomata regulate transpiration only during the periods of darkness and low light. This was concluded from a comparison of the values for the canopy resistance as derived from direct measurement on leaves and as calculated from the environmental data.

This finding predicts that, during the main part of the daylight period, neither an increase in number or aperture of stomata nor a wetting of the entire foliage would increase the evaporative flux. The action of the sorghum plant is then like that of a wick.

We also found that, in a hot and dry environment, the sorghum foliage will constantly be several degrees cooler than the ambient air, even in the middle of the day when radiant energy input is large. Finally, the energy equivalent of the evaporative flux exceeded the net radiant flux significantly at all times, and by 80% over a 24-hour period.

All three findings are at variance with common generalizations concerning the energetics and mechanics of crop transpiration. However, we recognize that our findings cannot be generalized to include other crop plants without specific studies.

Key Words: transpiration • canopy resistance

² Chief Physicist and Plant Physiologist, U. S. Water Conservation Laboratory, Phoenix, Ariz. Current affiliation of the first author is: Institute of Life Science, Texas A&M University, College Station, Texas.

Received for publication June 17, 1967.

This article has been cited by other articles:

				V. Bandaru, B. A. Stewart, R. L. Baumhardt, S. Ambati, C. A. Robinson, and A. Schlegel Growing Dryland Grain Sorghum in Clumps to Reduce Vegetative Growth and Increase Yield Agron. J., June 27, 2006; 98(4): 1109 - 1120. [Abstract] [Full Text] [PDF]

				W. K. SMITH Temperatures of Desert Plants: Another Perspective on the Adaptability of Leaf Size Science, August 18, 1978; 201(4356): 614 - 616. [Abstract] [PDF]