Identification of salt tolerant Acacia species for saline land utilisation

Abstract

The deleterious effects of soil salinity on biodiversity and agricultural productivity make it essential to devise strategies that would reduce its impact and expansion. For sustainable agriculture on dryland salinity affected areas, the use of native salt-tolerant plant species of economic value could provide a solution. In this work, the salinity tolerance potential of fifteen different Australian Acacia (wattle) species, pre-selected on the basis of phylogenetic relationships, were tested. The effects of salinity stress on morphological and physiological parameters, such as shoot and root lengths, shoot and root biomass, tissue water content, tolerance indices and accumulation of major cations (sodium, potassium, magnesium, calcium), all of which are indicators of salt stress response, were investigated. The species exhibited varied responses to the various parameters, some species consistently indicative of salt tolerance. Consolidating the tolerance indices based on morphological and physiological effects of salt stress, a method was developed to arbitrarily rank the species for their tolerance. Two highly tolerant, three tolerant and six moderately tolerant species could thus be identified. The work supports use of phylogenetics for initial screening for large genera, such as Acacia, and provides an experimental methodology for identification of candidate species for environmental stress tolerance and other applications.