Ethanol Synthesis and Water Relations of Flooded Pseudotsuga menziesii (Mirb.) Franco (Douglas-Fir) Seedlings under Controlled Conditions

Abstract

Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seedlings were flooded in a controlled environment. Roots rapidly synthesized ethanol with the highest rates during the first 6 h. Ethanol readily diffused into the flooding solution and moved into the stem. Ethanol concentrations in the flooding solution (normalized g-1 dry mass of roots) were four to six times the concentrations in the stems or roots. Ethanol concentrations in the roots and stems were six to 16 times larger than in the needles. Stomatal conductance and water uptake continuously increased during the first 96 h of flooding, whereas ethanol concentrations in the roots and stem increased to their maximum at 6-24 h after flooding and then decreased. Supplying Douglas-fir shoots with ethanol concentrations at two to three times those measured in flooded seedlings had no effect on stomatal conductance. Ethanol synthesis and accumulation in Douglas-fir seedlings in response to flooding does not have a detrimental impact on stomatal conductance ...