Screening for salt and waterlogging tolerance in Eucalyptus and Melaleuca species

Abstract

Seedlings of forty Eucalyptus and twenty Melaleuca species from within Australia were tested in three separate glasshouse experiments for their tolerance to the individual stresses of salinity and waterlogging as well as a combined salt/waterlogging stress. Waterlogging with freshwater had little effect on growth and survival of Melaleuca species but caused growth reduction for most Eucalyptus species. Under freely-drained conditions, salinity caused growth reduction in all species, while percentage survival remained high. Survival and growth for all species were reduced most in saline/ waterlogged conditions. Using a tolerance index combining survival and growth, the most tolerant Eucalyptus species to salt/waterlogging in the first experiment were E. occidentalis, E. sargentii and E. spathulata, and in the second experiment E. intertexta, E. microtheca, E. raveretiana, E. striaticalyx and E. tereticornis. Melaleuca lateriflora, M. sp. aff. lanceolata and M. thyoides were the most tolerant Melaleuca species for both freely-drained and saline/waterlogging stresses. Although these species showed greatest tolerance to salt/waterlogging conditions, there was wide variation for tolerance between provenances of most species in all treatments. Matching of species with sites should provide suitable choices for reclamation of saline seeps in Australia and other countries, and provide renewable resources of timber and fuelwood from habitats currently unavailable to agricultural or silvicultural production.