Drought tolerance and osmotic adjustment of four deciduous tree species under altered precipitation: Preliminary results

摘要

The degree and biochemical basis of drought tolerance and osmotic adjustment of dogwood (Cornus florida L.), white oak (Quercus alba L.), chestnut oak (Quercus prinus L.), and red maple (Acer rubrum L.) is being assessed in a mature hardwood forest using three hydrologic regimes: ambient, wet (+33% throughfall), and dry ((minus)33% throughfall). Currently, leaf water potential, osmotic potential at saturation, and metabolite concentrations are determined monthly for trees under the three treatments. First year results show that within the dry treatment, dogwood demonstrated the highest osmotic potential at saturation ((minus)1.2 MPa), indicating the greatest sensitivity to water stress. Increasing tolerance was evident in red maple ((minus)1.4 MPa), white oak ((minus)1.6 MPa), and chestnut oak ((minus)1.9 MPa). In June, dogwood displayed a 0.12 MPa adjustment to drought, relative to the ambient control. In July, chestnut oak displayed a 0.18 MPa adjustment. This osmotic adjustment resulted primarily from fructose and glucose accumulation in dogwood, and shikimic acid and sucrose accumulation in chestnut oak.