Root Respiration Characteristics of Flood-tolerant and Intolerant Tree Species1

Abstract

Abstract Red maple (Acer rubrum L.) and baldcypress (Taxodium distichum (L.) Rich.) seedlings were very tolerant of extended flooding, whereas shoots of sugar maple (Acer saccharum Marsh) seedlings experienced desiccation after 8 days of flooding, and leaf death after 14 days. Shoot desiccation occurred after 14 days of flooding. Roots of all 3 species utilized O2 with similar efficiency prior to flood stress. However, the respiratory capacity of sugar maple roots declined substantially during the first 8 days of flooding, and more gradually from 8 to 22 days, at 21, 5, or 0.5% O2. Red maple roots declined gradually in respiratory capacity over the entire flooding period at 21 and 5%, but not at 0.5% O2. After an initial sharp decline, baldcypress roots gradually regained capability to utilize O2 from 8 to 22 days of flooding at all 3 levels of O2. When tested at 21% O2, both red maple and baldcypress roots had 2- to 3-fold higher respiratory capacities than did sugar maple roots after 22 days of flooding. Presoaking root sections from flooded red and sugar maple in a sucrose solution mildly stimulated respiration rates measured at 21% O2, but did not fully restore respiratory capacity lost by flooding either species.