Biochemical basis of drought tolerance in hybrid Populus grown under field production conditions. CRADA final report

The purpose of this cooperative effort was to assess the use of osmotically active compounds as molecular selection criteria for drought tolerance in Populus in a large-scale field trial. It is known that some plant species, and individuals within a plant species, can tolerate increasing stress associated with reduced moisture availability by accumulating solutes. The biochemical matrix of such metabolites varies among species and among individuals. The ability of Populus clones to tolerate drought has equal value to other fiber producers, i.e., the wood products industry, where irrigation is used in combination with other cultural treatments to obtain high dry weight yields. The research initially involved an assessment of drought stress under field conditions and characterization of changes in osmotic constitution among the seven clones across the six moisture levels. The near-term goal was to provide a mechanistic basis for clonal differences in productivity under various irrigation treatments over time

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

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