Abstract:

Effects of some physiological processes of different fast-growing Eucalyptus clones (Eucalyptus grandis×E. urophylla Guanglin No.9, E. grandis×E. urophylla Guanglin No.12, E. urophylla Guanglin No.4, E. urophylla×E. camaldulensis No.3) were studied under different acid-aluminum treatments using the cultivation method of sand and soil mixture. The levels of acid-Al were respectively pH 3.0+0 mg ·L^-1 Al³⁺, pH 3.0+120 mg ·L^-1 Al³⁺, pH 4.0+0 mg ·L^-1 Al³⁺, pH 4.0+120 mg ·L^-1 Al³⁺, and the pH 4.8+0 mg ·L^-1 Al³⁺ served as the control. The results showed that different acid-Al treatments changed membrane permeability, MDA content, protein content, proline content and soluble sugar content of 4 fast-growing Eucalyptus clones. The low pH and high concentration of Al decreased the membrane permeability, increased peroxide level of membrane and influenced synthesis of protein and soluble sugar contents. At the same time, the seedlings cumulated more proline which protected themselves from the stress. Compared to pH 4.8+0 mg ·L^-1 Al³⁺, the treatments of pH 3.0+120 mg ·L^-1 Al³⁺ significantly inhibited the seedlings. Based on change ranges of the physiological indexes, E. grandis×E. urophylla Guanglin No.9 showed better adaptation and resistance to the acid-aluminum treatments than other clones. The resistance was ranked as Eucalyptus grandis×E. urophylla Guanglin No.9>E. grandis×E. urophylla Guanglin No.12>E. urophylla Guanglin No.4>E. urophylla×E. camaldulensis No.3 in turn.

Key words: pH, aluminum, physiological characteristics, clones, Eucalyptus