Effect of Soil Drought on Concentrations of Organic Solutes in Needles and Roots of Three Coniferous Species (Cedrus atlantica Manetti, Pseudotsuga macrocarpa (Torr) Mayr., Pseudotsuga menziesii (Mirb.) Franco

1988

1 Abb., 3 Tab., 26 Lit. Ang., Fr, Zfsg. En, Fr

Unselbständiges Werk

2819

200014557

The authors describe variations in concentrations of someorganic solutes for three conifers. Results were obtained from two experiences , one in the field testing 9 species and various provenances of douglas fir, and a test under controlled conditions for the 3 following species: Pseudotsuga mcacrocarpa, Pseudotsuga menziesii, Cedrus atlantica. Stress level is expressed as predawn xylem water potential, the concentrations of the following organic soluted were measured on each foliar or root sample: glucids, polyols, soluble amino acids and proline. Solutes concentrations vary between species for a same water stress level, rates of changes in concentrations for different water stresses levels also differ from one specie to another. For douglas fir, amounts ofsoluble sugars are increasing along with water stresses while no specific tren ds were observed for Cedrus atlantica. Foliar extractions of polyols were similar not withstanding the stress level applied; however significant differences in roots concentrations of polyols are observed between the three species. For douglas fir submitted to a predawn xylem water potential below - 2.0 MPa, there is a strong increase in free amino acids and proline contents. Amounts of amino acids and proline extracted from roots of all species and needles of cedarare small and do not increase with stress. Weak responses and changes occuring at high levels of stresses (beyond - 2.0 MPa) suggest that other solutes, poss ibly minerals, may intervene, in the osmotic adjustments following water stress.