Flood-Tolerance Ranking of Red and Freeman Maple Cultivars
Louis B. Anella and Thomas H. Whitlow
Abstract: Red maple (Acer rubruni) is often recommended for use in wet soils, yet its extensive native range suggests there may be genetic variation for traits associated with flood tolerance. Likewise, genetic variation for flood tolerance may be captured within red maple cultivars making some more appropriate than others for use in wet or low oxygen soils. Seven red maple cultivars (2-year-old trees)—'Autumn Flame'®, 'Bowhall', 'Karpick', 'Northwood', 'October Glory'®, Red Sunset®, and 'Schlesinger— and 4 Freeman maple (A. xfreemanii) cultivars—' Armstrong', 'Autumn Blaze', 'Morgan', and Scarlet Sentinel™, were ranked for flood tolerance by flooding the trees and characterizing photosynthesis, lenticel intumescence, and survival. Indicator trees representing the wet extreme of red maple's native range were also included for comparison. Net photosynthesis declined for all cultivars; however, 'Schlesinger', Red Sunset and 'Bowhall' had the highest net photosynthetic rates (ranging from 1.94 to 1.71 umol/m2s) after 45 days of flooding. In contrast, 'Karpick', 'Autumn Flame', and 'Northwood' had net photosynthetic rates near 0. The extent of lenticel intumescence also varied among the cultivars with 'Schlesinger' and 'Bowhall' producing the longest lenticels. All of the 'Northwood' trees died, as did two-thirds of the Autumn Flame' trees. The cultivars were separated into 3 overall flood-tolerance rankings: high ('Schlesinger', Red Sunset, and 'Bowhall'), intermediate (Armstrong1, 'Morgan', 'October Glory', Scarlet Sentinel, and Autumn Blaze'), and low ('Karpick', Autumn Flame', and 'Northwood').
Keywords: Genetic variation; lenticel intumescence; photosynthesis; red maple (Acer rubrum L.); Freeman maple (A. x freemanii E. Murray).