Effects of exposure to air on planting stress in red oak seedlings

Abstract

One-year-old bare root red oak (Quercus rubra L) seedlings were lifted in March and exposed to desiccating conditions (darkness, 8 °C and 60% relative humidity) for 0, 2, 5.8 and 12 days before planting in mini-rhizotrons. Water content and concentration in soluble carbohydrates and starch were measured in buds, stems and roots after treatment before planting. These variables were related to root and shoot growth after planting. Fifty percent of the seedlings exposed for 12 days did not regenerate new roots and died. No mortality was observed for the shorter exposure durations. Seedlings exposed for 0.2 and 5 days displayed similar new root elongation values after planting which were three-fold higher than those observed in seedlings exposed for 8 or 12 days. Exposure also induced bud abortion and formation of epicormic shoots. These perturbations appeared to be related to the desiccation of the different plant components, whereas non-structural carbohydrate concentrations were not affected during the exposure phase.