Articles
CARBON ISOTOPE DISCRIMINATION AND TRANSPIRATION EFFICIENCY IN EUCALYPTUS UNDER SALINITY AND BORON STRESS
Article number
537_22
Pages
215 – 222
Language
Abstract
We tested the hypothesis that stable carbon-isotopic composition in Eucalyptus trees can be an indicator of the cumulative salinity and boron stress history of the plant.
In a controlled, outdoor sand-tank study, Eucalyptus camaldulensis saplings were irrigated with combinations of salinity (EC 2 to 28 dS m-1) and B (1 to 30 mg l-1) to determine their influence on tree growth, water use, and stable carbon-isotope discrimination.
Our results indicate carbon-isotope discrimination (D) was primarily reduced by salinity stress, whereas boron effects were smaller in magnitude and significant only at low salinity.
Carbon-isotopic discrimination in leaves of Eucalyptus varied with position in the canopy.
For example, proximal leaves sampled low in the canopy D decreased from 23.6 ‰ at low salinity (2 dS m-1 and 1 mg l-1 B) to 22.6 ‰ at high salinity (22 dS m-1 and 1 mg l-1 B). In distal leaves sampled high in the canopy, D decreased from 21.1‰ to 19.8‰ in corresponding treatments.
Isotopic discrimination in woody tissue from tree trunks also correlated well with salinity stress.
Moreover we found the relationship between D and EC of the irrigation water was similar to that of biomass and EC suggesting that D may be useful in describing salt tolerance in as well as quantifying the salt-stress history in C3 trees.
There was a significant relationship between isotope discrimination in leaf and wood tissue with transpiration efficiency.
The relationship was position sensitive for leaves and correlations with wood tissue increased with time under stress.
In a controlled, outdoor sand-tank study, Eucalyptus camaldulensis saplings were irrigated with combinations of salinity (EC 2 to 28 dS m-1) and B (1 to 30 mg l-1) to determine their influence on tree growth, water use, and stable carbon-isotope discrimination.
Our results indicate carbon-isotope discrimination (D) was primarily reduced by salinity stress, whereas boron effects were smaller in magnitude and significant only at low salinity.
Carbon-isotopic discrimination in leaves of Eucalyptus varied with position in the canopy.
For example, proximal leaves sampled low in the canopy D decreased from 23.6 ‰ at low salinity (2 dS m-1 and 1 mg l-1 B) to 22.6 ‰ at high salinity (22 dS m-1 and 1 mg l-1 B). In distal leaves sampled high in the canopy, D decreased from 21.1‰ to 19.8‰ in corresponding treatments.
Isotopic discrimination in woody tissue from tree trunks also correlated well with salinity stress.
Moreover we found the relationship between D and EC of the irrigation water was similar to that of biomass and EC suggesting that D may be useful in describing salt tolerance in as well as quantifying the salt-stress history in C3 trees.
There was a significant relationship between isotope discrimination in leaf and wood tissue with transpiration efficiency.
The relationship was position sensitive for leaves and correlations with wood tissue increased with time under stress.
Authors
J.A. Poss, D.L. Suarez, C.M. Grieve, M.C. Shannon, S.R. Grattan
Keywords
Eucalyptus camaldulensis, 13C discrimination, salt stress, salt tolerance
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