Seedlings of 2 ornamental tree species, Tilia cordata Mill, (littleleaf linden) and Acer platanoides L. (Norway maple) were grown outdoors in containers for 1 season under 6 N regimes (0, 52.5 105, 210, 420, and 840 ppm N) in a turface/peat medium. At 6, 12, and 15 weeks, plants were harvested, growth parameters measured, and data analyzed by covariance. Optimum growth under the conditions imposed by the experiment occurred at 210 and 420 ppm N, although the response of A. platanoides was less consistent than that of T. cordata. Zero, 52.5, and 840 ppm N limited growth.
Root lengths of an adventitious root system (creeping bentgrass, Agrostis palustris Huds.) and a woody plant fiberous root system (Hetz juniper, Juniperus chinensis L. ‘Hetzii’) were estimated using an automated method employing a video camera and an area/length meter to count scanning line and root intersections. A grid method of root length estimation was used for comparison. Under- and overestimation was random when the automated method was used for creeping bentgrass samples (<80 cm) and the shorter group of juniper root samples (150-550 cm). However, these estimates were much closer to the actual root length, in the ranges evaluated, than the estimates from the grid method. The lengths of long juniper root samples (600-3000 cm) were underestimated consistently with the automated method. The magnitude of this underestimation increased with increasing length. However, the relationship between estimated and actual root length remained linear and was about 76% of the actual length. For the ranges of root length evaluated, this method was found to be useful for root length estimation.