Articles
RESPONSE OF ACER RUBRUM L. (RED MAPLE) GENOTYPES AND CULTIVARS TO SOIL ANAEROBIOSIS
Poor soil drainage is encountered in street tree pits due to compaction of the native soil and textural differences between the native soil and the rootball and backfill.
This drainage restriction causes the so-called “teacup effect” in which the tree pit soil becomes waterlogged and subsequently anaerobic, to the detriment of the trees.
Site design could avoid this problem, yet is often neglected or not completely effective.
We investigated red maple as a source of genetic material able to cope with soil anaerobiosis because its ecological range in North America includes both wet and dry soils and because it is a popular ornamental tree, with many cultivars available in the nursery trade.
We screened both existing cultivars and native populations for their tolerance of poor soil aeration.
When flooded during the growing season, seedlings derived from maternal sources growing on waterlogged sites produced hypertrophied lenticels and adventitious roots, maintained higher leaf gas exchange rates and recovered more completely when soil was drained than seedlings derived from dry site sources.
This suggests that wet site populations are genetically distinct from dry site populations and could be exploited to develop especially flood tolerant cultivars.
Eleven commercial cultivars developed for ornamental traits with no a priori expectation of differential responses to flooding showed a range of responses similar to native sources.
These cultivars were ranked into three categories of flood tolerance: High-Schlesinger, Red Sunset® and ‘Bowhall’; Intermediate- Armstrong, Morgan, ‘October Glory, Scarlet Sentinel™ and ‘Autumn Blaze’®; Low- Karpick, ‘Autumn Flame’® and ‘Northwood’.