Effects of plant density (1, 2, 4 or 8 plants) and root excision (detipping the terminal 1 mm of root apices) were investigated during the life of 16 day-old corn plants. Few differences were exhibited in organ (kernel, root or shoot)or overall plant biomass when comparing intact to excised plants. Comparing organ biomss of the 4 plant densities within each group did reveal differences, however. These differences were especially evident when comparing biomass values at the maximum density (8 plants grown together) to the 3 lower plant densities of the excised group. Decreased values of root and shoot dry weights occurred in plants maintained in groups of 8. In both intact and excised plants and at all 4 plant densities, kernel and root dry weights exhibited the highest and lowest biomass proportions, respectively. The average kernel weight was nearly 45%, while roots averaged 31% of the total plant biomass. Only single intact plants were exceptions, where root biomass exceeded kernel weight (40% to 29%). The number of roots produced per plant was significantly greater in excised seedlings. This increased root number was noticeable in 9 day-old plants and continued at all densities throughout the 16 day study. The range of increased root number was 1 1/3 - 2 times. The length of primary roots was longer in intact seedlings, first being evident in 7 day-old seedlings. By the time plants were 16 days old, intact plants had primary roots ranging from 2 3/4 - 5 times longer. In excised plants, rates of primary root elongation were negligible during the 16 day study. Primary root elongation in intact plants averaged 1 1/4 - 2 cm per day at all densities.

Key words: corn, density, excision, maize, root, Zea mays