Abstract: Two mustard varieties’ (Brassica juncea var. multiceps Tsen et Lee and Brassica juncea var. crispifolia Bailey) seedlings were cultured in sand which was dipped in nutrient solution added different concentrations of aluminum (0, 1, 10, 100 mg·L ^{- 1} Al^{3 +} ). The change of the rootmorphology and the content
of MDA, AsA and GSH aswell as POD, CAT and SOD activities in leaves were determined. The result indicated that lower concentrations of aluminum (1 mg·L ^{- 1} and 10 mg·L ^{- 1} ) could promote the root growth and decrease the MDA content in two mustard varieties'leaves on the 15th day. With increase of aluminum, the root growth was inhibited and the MDA content in two varieties'leaves was increased compared with the control, and the activities of POD and CAT were also promoted obviously, but the response of AsA and GSH content aswell as SOD activity in different varieties were different to aluminum stress. It is suggested that lower aluminum concentrations could promote the growth of mustard seedlings in a short time. Antioxidant enzymes
played an important part in resisting aluminum.

Key words: Brassica juncea var. multiceps Tsen et Lee, Brassica juncea var. crispifolia Bailey, Aluminum, Rootmorphology, Reactive oxygen species, Antioxidant system