The Allium test: injection of test compounds into the bulb.

We developed three methods for injecting substances into the bulb of Allium: (1) direct injection, (2) injection through the open space in the bulb after the removal of the upper half of the bulb, and (3) through a special "tunnel" cut in the bulb. Water (control) and solutions of methotrexate and copper sulfate were injected into bulbs and the dynamics of root growth were measured. We found that 2.2 mM methotrexate and 100 mM copper sulfate inhibit root growth. Injection through the "tunnel" was the most effective method. Cytological analysis showed that methotrexate inhibited mitotic activity completely in the root apical meristem and copper sulfate induced swelling of cells in the root meristem.