FIG. 4.

Soil populations of UW85 and UW2000 in the presence of alfalfa cultivar Iroquois seeds. Each soil sample (50 mg) was placed in a well of a 96-well microtiter dish along with one surface-sterilized alfalfa seed and was inoculated with approximately 10³ UW85(pBC16) or UW2000(pBC16) vegetative cells. At zero time (A) and at 48 h after inoculation (B), bacterial populations were determined on 0.1× TSA containing 10 μg of tetracycline per ml. The data are from three separate experiments.