Abstract: By the method of sand culture, this paper studied the effects of different concentration (0, 50, 100, 150, and 200 μmol·L^-1) aluminum (Al) on the root length, root dry weight, root plasma membrane permeability, root total absorption area, root active absorption area, and root activity of Pinus massoniana seedlings after 30, 60, and 100 days of treatment. Low concentration (0-50 μmol·L^-1) Al had less impact on the physiological characteristics of root system, medium Al stress (100 μmol·L^-1) was the turning point for the root growth and activity, while high Al (150-200 μmol·L^-1) decreased the root physiological indices markedly. Root length, root mass, root plasma membrane permeability, and root activity could be used as the identification indices of Al toxicity during the seedling stage of P.massoniana. When the rhizosphere Al treatment was less than 30 days, the P. massoniana seedlings had stronger adaptability, and the root growth was less inhibited; when the stress was longer than 30 days, the root responses would be more severe with extending stress time.

Key words: Acer truncatum, Flushing method, Hydraulic character