Interactions between temperature, drought and stomatal opening

Fig. 1. Influence of temperature on stomatal aperture of bean (Phaseolus vulgaris) leaves exposed to elevated temperature in darkness. Leaf segments were floated on
deionised water heated to indicated temperature for 0, 10, 20, 40 or 60 min, then photographed. Some stomata are encircled for clarity.

Interactions between temperature, drought and stomatal opening in legumes

by Reynolds-Henne C. E., Langenegger A., Mani J., Schenk N., Zumsteg A., Feller U. (2010)

Christina E. Reynolds-Henne, Anita Langenegger, Jan Mani, Nicole Schenk, Anita Zumsteg, Urs Feller ∗
Institute of Plant Sciences (IPS) and Oeschger Centre for Climate Change Research (OCCR), University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland

In Environmental and Experimental Botany 68: 37–43 –

https://boris.unibe.ch/5379/1/2010_JExpBot_68_37.pdf

Abstract

The effect of heat and drought on stomatal behaviour of 2–4-week-old legumes, bean (Phaseolus vulgaris
L.) and red clover (Trifolium pratense), was investigated. Drought stress was induced by complete water
deficit or with polyethylene glycol (PEG), and abscisic acid (ABA) was applied to mimic plant drought
response. Heat stress was simulated by water bath (leaf segments) and infrared and halogen lighting
(whole plants). Various experimental conditions were studied: high temperature alone or combined
with drought, and low or high photosynthetically active radiation (PAR). Stomatal opening was either
measured directly or determined using thermal imaging as a proxy.When water was not limiting, stomata
opened in darkness under heat stress. At high PAR, drought and moderate heat caused increased leaf
temperatures and temperature oscillations (±3–4 ◦C), attributed to the opening and closing of stomata.
At low PAR, heat led to leaf temperature oscillations in control plants, whereas the application of drought
caused stomatal closure, increasing leaf temperature to 39 ◦C. Stomatal opening occurred under high
temperatures, despite the presence of the drought-induced hormone ABA, and was maintained into a
recovery period at room temperature for 30 min. This study helps to illustrate stomatal plasticity and the
interplay between leaf gas-exchange and maintaining favourable metabolic conditions (water status and
temperature) within the leaf. Knowledge of how legumes are affected by two environmental stresses,
heat and drought, expected to occur simultaneously with greater frequency in the future, is important in
determining overall plant survival strategies.