Guarnaschelli, A.B., Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina
Prystupa, P., Departamento de Ingeniería Rural Y Uso de la Tierra, Facultad de Agronomía, Universidad de Buenos Aires, Argentina
Lemcoff, J.H., Dep. Environ. Physics and Irrigation, Institute of Soil, Water and Environmental Sciences, Volcani Center, PO Box 6, Bet Dagan 50250, Israel

We investigated the responses of drought preconditioning in three provenances of Eucalyptus globulus subsp. bicostata (Maiden, Blakely and J.Simm) J.B. Kirkp. seedlings and assessed their effects after transplanting. After one-month moderate drought conditioning treatment, seedlings evidenced osmotic adjustment, reduction in size, leaf area, shoot/root ratio and stomatal conductance. Inter-provenance variation was found in osmotic adjustment capacity. During the first stages of transplanting period, pretreated plants showed improved water status and gas exchange capacity under drought conditions; this initial superiority was lost later on. Non-conditioned seedlings also developed morphological and physiological adjustments that allowed them to perform similarly to conditioned plants. Although preconditioning did not favour seedlings growth, it was effective in enhancing survival, an attribute correlated to shoot/root ratio and relative water content. Inter-provenances variation was found in several of the physiological and morphological responses to drought, but it was not possible to relate that variation to the dryness of the seed origin site. These results show the advantage of drought preconditioning in Eucalyptus globulus subsp. bicostata which result in better behaviour and greater survival after transplanting, factors closely associated with the establishment success. © INRA, EDP Sciences, 2006.