The cytotoxic influence of aluminium on Cucumis sativus L seedling roots

The roots of 5-days old cucumber seedling cv. Wisconsin were incubated in the Al solutions (AICl3) of pH 4,2. AI was applied in the following concentrations: 20, 30 and 40 mg/dm3. All the Al concentrations caused both the inhibition of root elongation and reduction of mitotic activity of apical meristem. The complete inhibition of mitoses and elongation growth was determined in the presence of 30 and 40 mg Al/dm3 after 4 and 3 days of incubation. After 5 incubation days the changes in the morphology of seedling roots, resulting mainly from the inhibition of the main root elongation and formation of a greater number of lateral roots, were noted. The reduction of root cap dimensions was accompanied by the apical meristem shortening and in short distance, differentiation of numerous lateral root primordia. The meristematic cell got elongated while their nuclei and nucleoli enlarged (particularly at 20 and 30 mg Al/dm3) and cytoplastn vacuolized. In the region of elongation and lateral roots differentiation, the cells of epidermis and primary cortex got shrunk, degenerationed and after falling off the tissue they made bigger (40 mg Al/dm3) or smaller (20 and 30 mg Al/dm3) hollows and cracks on the outer side of the root