Drought is considered the main environmental factor limiting productivity in eucalyptus plantations in Brazil. However, recent studies have reported that exposure to water deficit conditions enables plants to respond to subsequent stresses. Thus, this study investigates the ecophysiological acclimatization of eucalyptus clones submitted to recurrent water deficit cycles. Eucalyptus seedlings were submitted to three recurrent water deficit cycles and anatomical, morphological and physiological changes were analyzed. The results were: (1) Eucalyptus seedlings responded to water deficits by directing carbohydrates to root and stem growth; (2) Size and number of stomata were reduced; (3) Stomatal conductance decreased which allowed the plants to reduce water losses through transpiration, increasing instantaneous water use efficiency; (4) The relationship between gas exchanges and available water contents allowed the seedlings to uptake the retained soil water at higher tensions; and, (5) Physiological recovery from subsequent water deficits became faster. As a result of these changes, the eucalyptus seedlings recovered from the same degree of water stress more rapidly.

干旱被认为是限制巴西桉树人工林生产力的主要环境因素。然而，最近的研究报告说，暴露于缺水条件可使植物对随后的胁迫做出反应。因此，本研究调查了面临反复缺水周期的桉树无性系的生态生理适应性。桉树幼苗经历了三个反复的水分亏缺循环，并对其解剖，形态和生理变化进行了分析。结果是：（1）桉树幼苗通过引导碳水化合物促进根和茎的生长来应对缺水。（2）减少了气孔的大小和数量；（3）气孔导度的降低使植物减少了蒸腾作用的水分流失，提高了瞬时用水效率。（4）气体交换与有效水分之间的关​​系使幼苗在较高的张力下吸收保留的土壤水分；（5）从随后的水分亏缺中恢复生理的速度更快。这些变化的结果是，桉树幼苗从相同程度的水分胁迫下恢复得更快。