Planta

, Volume 224, Issue 3, pp 680–691

Water stress impacts on respiratory rate, efficiency and substrates, in growing and mature foliage of Eucalyptus spp

Original Article

DOI: 10.1007/s00425-006-0247-7

Cite this article as:
Callister, A.N. & Adams, M.A. Planta (2006) 224: 680. doi:10.1007/s00425-006-0247-7

Abstract

In previous studies, water stress has induced variable and sometimes contradictory changes in respiration. We used isothermal calorimetry to measure the response of foliar respiration to water deficit in nine eucalypt genotypes. Specific growth rates (RSG) of shoots and leaves of variable age were measured independently, and the data were applied to both the growth-maintenance and enthalpy balance models. We calculated the oxidation state of respiratory substrate and the enthalpy change for the conversion of substrate carbon to biomass (ΔHB). Moderate water stress reduced the RSG of shoots by 38% (P<0.01) and carbon conversion efficiency by 15% (P<0.05). The relationship between carbon conversion efficiency and RSG was not affected by water deficit for shoots, but was significantly altered for leaves. Water deficit increased maintenance respiration by about 23% (P<0.001). The growth coefficient of respiration was not significantly altered. However, changes in oxidation states of substrate and biomass suggest that the energy requirements of biosynthesis were increased under water stress. Our results confirm that carbohydrates are the major respiratory substrates in growing tissues, though mature leaves utilized a substantial component of more reduced substrate. Mature leaves had variable oxidation states for respiration substrate, which indicates a variable relationship between CO2 evolution and ATP production. Measured ΔHB in shoots and leaves were too small for reliable estimation of RSG by the enthalpy balance model. We also found significant effects of water stress on the oxidation state of substrate and ΔHB.

Keywords

Calorimetry Eucalyptus Oxidation state Respiration Substrate Water stress 

Abbreviations

ΔHB

Enthalpy change for conversion of substrate carbon to biomass

\( \Delta H_{{{\text{O}}_{2} }} \)

Enthalpy change for catabolism of carbon substrate per mol O2 consumed

εC

Carbon conversion efficiency

g

Growth coefficient of respiration

γB

Oxidation state of biomass

γS

Oxidation state of respiratory substrate

m

Maintenance coefficient of respiration

P/O

Ratio of oxidative phosphorylation to oxygen consumption

RATP

Specific rate of ATP production

\( R_{{{\text{CO}}_{{\text{2}}} }} \)

Specific rate of CO2 evolution

\( R_{{{\text{O}}_{2} }} \)

Sspecific rate of O2 consumption

Rq

Specific rate of heat evolution

RSG

Specific growth rate

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.School of Forest and Ecosystem ScienceUniversity of MelbourneCreswickAustralia
  2. 2.Centre of Excellence in Natural Resource ManagementUniversity of Western AustraliaCrawleyAustralia

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