Abstract: [Objective] Poplar are a sort of plants that are usually for planting in neutral to partially alkaline soil, however the fast development of new varieties for cultivation has expanded its planting range. A-61/186(Populus × euramericana cv.A-61/186) is a evergreen poplar clone that is suitable for low-latitude tropical and subtropical areas, and it has been introduced to Fujian Province of China and presents evergreen characteristics. However, when it is planted in tropical or subtropical areas, it faces a prominent issue of acidic soil in which aluminum is rich, which can bring adverse effects. In this study, the patterns of aluminum accumulation and distribution in the body, the response of leaf ultrastructure and the physiological indexes under the condition of acid aluminum were investigated. The study aims to reveal mechanism of the macro and micro structure of the evergreen Poplar adapting to aluminum stress, thus providing a theoretical basis for the widespread of the evergreen poplar in subtropical regions. [Method] In this study, and the evergreen poplar clone ‘A-61/186’ was grown in hydroponic solution for aluminum stress experiment, and the effects of aluminum stress on the growth, biomass, chlorophyll fluorescence indicator and leaf ultrastructures by using transmission electron microscopy(TEM) were studied systematically. [Result] The results showed that the acidic aluminum stress had an impact on the growth of the evergreen poplar; the acidic aluminum stress significantly decreased the growth of roots, stems, and leaves as well as biomass of the evergreen poplar, and it had a much greater impact on the underground part than the above ground part. In addition, aluminum was accumulated more readily in the roots than in the stems and leaf tissues. Chlorophyll fluorescence showed that the absorbed light was non-photochemical and dissipated under aluminum stress, which reduced its photosynthetic efficiency, thereby affecting the growth and biomass. Furthermore, the degree of injury to the mesophyll cell ultrastructure is consistent with the growth and chlorophyll fluorescence parameters, which indicated that the effects of aluminum stress on the evergreen poplar clone's growth and biomass were directly related to the damage to the photosynthetic system.[Conclusion] With regards to the aluminum content in the evergreen poplar clone and the aluminum concentration that inhibited growth, the evergreen poplar clone was more sensitive than acidic species, such as tea, longan, and eucalyptus. Therefore, when planting this evergreen poplar clone in acidic soil, aluminum toxicity should be considered.

Key words: evergreen poplar clone, aluminum stress, growth, aluminum content, leaf ultrastructure