Morphological and Physiological Comparisons of Clonal Lines of Eucalyptus camaldulensis. II. Responses to Waterlogging/Salinity and Alkalinity

Abstract

Eucalyptus camaldulensis Dehnh. has previously been shown to survive and grow in waterlogged, highly saline and highly alkaline soils. The ability of six clones from five provenances of E. camaldulensis to produce biomass and utilise water, and the processes of stomatal conductance and gas exchange under stress conditions was examined under controlled conditions in a glasshouse. A clone originally from Wooramel, Western Australia (M80) produced the largest total plant biomass, the greatest total leaf area and greatest total root dry weight under conditions of waterlogging and gradually increasing salinity. A second clone from Wooramel (M16), however, tended to be among the least productive of the clones under this stress, indicating the wide potential variation in stress tolerance of trees from a single provenance.

The response of clones to alkalinity stress was comparable to that measured under waterlogging/salinity stress. Water use was closely related to biomass production. Leaves produced while under salinity and alkalinity stress were comparable in ion content to those produced prior to the test conditions. An ability to control uptake by roots or limit ion transport to leaf tissues were hypothesised as controlling physiological functions resulting in tolerance to severe soil ion imbalances in this species. The impact of solution conductivity on stomatal conductance and water use, secondarily affected photosynthetic rates in these clones of E. camaldulensis. Tolerance of extreme conditions provides the opportunity to use these genotypes to reclaim damaged agricultural landscapes and mine spoils of high soil solution ion concentrations.