Planta

, Volume 171, Issue 4, pp 466–473

Water stress in Eucalyptus pauciflora: comparison of effects on stomatal conductance with effects on the mesophyll capacity for photosynthesis, and investigation of a possible involvement of photoinhibition

Authors

  • Miko U. F. Kirschbaum
    • Department of Environmental Biology, Research School of Biological SciencesAustralian National University
Article

DOI: 10.1007/BF00392293

Cite this article as:
Kirschbaum, M.U.F. Planta (1987) 171: 466. doi:10.1007/BF00392293

Abstract

Seedlings of Eucalyptus pauciflora Sieb. ex Spreng., grown in 4-1 pots, were stressed by withholding water while relationships between net assimilation rate (A) and intercellular partial pressure of CO2 (pi) in selected leaves were obtained repeatedly throughout the stress cycle. Water stress at first caused stomatal closure without any decline in the A(pi) relationship. As stress became more severe, the A(pi) relationship was affected as well. This always affected assimilation rate at both high and low intercellular partial pressures of CO2. It was then tested whether water-stressed leaves were more prone to photoinhibition than unstressed ones. Plants were water-stressed while at the same time subjected to strong photon flux area density (2000 μmol quanta·m-2·s-1). A possible light-induced inhibition was assessed by comparing quantum yields of photosynthesis with light directed onto one or the other surface of the leaf. A decline in quantum yield was observed, and the decline on the previously irradiated side was more pronounced than on the previously shaded side, but the effect was small and disappeared entirely within 1 d of rewatering the plants. It is concluded that photoinhibition can play a role, but not an important one, in the effect of water stress on the A(pi) relationship in leaves of E. pauciflora.

Key words

Eucalyptus Gas exchange Photoinhibition Photosynthesis and water stress Stomatal conductance Water stress

Abbreviations and symbols

RuBP

ribulose-1,5-bisphosphate

A

net assimilation rate

pi

intercellular partial pressure of CO2

α

quantum yield of photosynthesis (net assimilation or RuBP-regeneration rate)

Δw

difference in water content between air saturated at leaf temperature and the actual vapor content of the air, expressed as mole fraction

Copyright information

© Springer-Verlag 1987