Stomatal aperture is the principal controlling agent in leaf senescence

 

Photo credit: Google

Oat seedlings

Relation between leaf senescence and stomatal closure: Senescence in light

by Thimann K. V., Satler S. O. (1979)

  1. Kenneth V. Thimann
  2. Sergio O. Satler

in Current Issue  76 no. 5 ,  2295–2298 – 

http://www.pnas.org/content/76/5/2295

Abstract

Senescence of isolated oat seedling leaves, floating on water or solutions in white light, has been followed by the disappearance of chlorophyll and the liberation of free amino nitrogen. In parallel, measurements of stomatal aperture were made with a diffusion resistance porometer, and borne out also by changes in fresh weight.

The stomata open as expected in the light but slowly begin to close after the first day; correspondingly, in the dark they close at once but gradually begin to open on successive days.

Abscisic acid causes closure and this is accompanied by senescence. Phenylmercuric nitrate also causes closure and again the reaction is closely paralleled by senescence.

Kinetin maintains stomatal opening even more than does light alone, and this is accompanied by complete prevention of chlorophyll loss for at least 5 days. Covering the leaf surface with a film of Vaseline, especially when detergents are added, accelerates senescence.

Merely floating the leaf segments on hypertonic solutions of sucrose or mannitol suffices to bring the rate of senescence in light up to the rate in darkness.

It is concluded that the effect of light in delaying senescence is primarily due to its effect on the stomatal aperture, and, more generally, that stomatal aperture is the principal controlling agent in leaf senescence.

Advertisements

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s