© 1994 Heron Publishing—Victoria, Canada
Prospects for increasing the salt tolerance of forest trees: a review
James A. Allen (1), Jim L. Chambers (2) and Michael Stine (2)
1. National Biological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, LA 70506, USA / 2. School of Forestry, Wildlife and Fisheries, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural
Center, Baton Rouge, LA 70803, USA / Received July 19, 1993
Summary
Three major themes related to the improvement of salt tolerance in forest tree species are examined. First, evidence demonstrating
that substantial intraspecific variation in salt tolerance exists in many species is presented. This evidence is important
because it suggests that efforts to improve salt tolerance through conventional plant breeding techniques are justified. Second,
the physiological and genetic mechanisms controlling salt tolerance are discussed briefly. Although salt tolerance involves
the integration of numerous physiological processes, there is considerable evidence that differences in the ability to exclude
Na+ and Cl– from leaves are the most important factors underlying intraspecific differences in tolerance. It is also becoming apparent
that, although salt tolerance is a multigenic trait, major genes play an important role. Third, progress to date in improving
salt tolerance of forest tree species is assessed. Compared with agricultural crops, relatively little progress has been made
with either conventional or biotechnological methods, but field trials designed to test clones identified as salt tolerant
in screening trials are underway now in several countries. We conclude that there is justification for cautious optimism about
the prospects for improving salt tolerance in forest tree species.
Keywords:
ion toxicity, salinity, salt avoidance, tissue tolerance, waterlogging.
