Sensitivity of different ecotypes of beech trees (Fagus sylvatica L.) to drought stress | Sensitivität von Ökotypen der Buche (Fagus sylvatica L.) gegenüber Trockenstreß
2000
Rennenberg, H. (Heinz) | Schraml, Carmen
In the present study, ecotypes of beech (Fagus sylvatica L.) were subjected to drought conditions from July to October 1997 in a water-exclusion experiment. The ecotypes originated from different regions of Baden-Württemberg with different environmental and climatic conditions. The intensity of drought-stress was determined by pre-dawn water potential and water content of the leaves. In the control plants, leaf water potential was −1,18±0,24 MPa, whereas values of −1,96±0,35 MPa were found under drought conditions. The reduction in leaf water potential was statistically significant in the ecotypes Conventwald and Zwiefalten. Still the water content (FW/%) of the leaves of all ecotypes did not respond to water exclusion. From the biometric parameters studied only the length of terminal branches was influenced by drought. The stress response of the ecotypes of beech was quantified by the concentration of malondialdehyde, electrolyte conductance and accumulation of proline in the leaves. The accumulation of proline showed ecotype-specific reactions to drought. Proline accumulated extensively in the leaves of the ecotypes Forbach and Überlingen, whereas the ecotypes Conventwald, Ravensburg and Zwiefalten showed no appreciable increase in proline content. The concentration of malondialdehyde in the leaves, irrespective of ecotypes, was significantly increased under drought stress, but no significant differences in the concentrations of malondialdehyde between the ecotypes were observed. Water exclusion induced a slight increase in the electrolyte conductance of the leaves of the ecotypes Conventwald and Zwiefalten.
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