Selection of Trees for Tolerance to Salt Injury
Michael A. Dirr
Abstract: No plants are wholly immune to salt injury and this should be considered before any type of breeding-screeningselection process is initiated. Salinity, like other stressful features of the environment, results in the evolution of races, or ecotypes adapted to it. The possibility of breeding salt tolerance into plants exists, but the strategy has not been tried in any sustained energetic manner. Salt usage, especially deicing, is increasing yearly. Plants growing along highways, on lawns, and along sidewalks exhibit stem dieback, and many are killed. The salts are deposited as spray on buds, stems, and leaves or are accumulated in the root zone. Subsequent injury results from osmotic and/or specific ion effects. Evaluations of salt-induced injury should be based on salts, concentrations, application methods, osmotic effects, shoot or leaf contents of Cl, and perhaps, shoot levels of Na. The appearance of the plant is not always reflective of the salt-induced damage, and growth parameters should be used to augment visual evaluations.