Response to Water Stress of Italian Alder Seedlings from Diverse Geographic Origins

1989

S. 1071-1076

4 Abb., 1 Tab., 18 Lit. Ang.

Unselbständiges Werk

200088360

Canadian Journal of Forest Research 1989 ; 19(8), S. 1071-1076

The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnus cordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reductin of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure-volume curves, were between -0.9 and -1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was oberved, after rewatering. Some differences between provenances were detected. The provenance from Corsico showed the greatest sensitivity to water stress; a seed source from the province of Acellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.