Abstract

Red oak (Quercus rubra L.) seedlings and ‘Autumn Flame’ red maple (Acer rubrum L.) rooted cuttings were grown under different fertility levels: 0, 25, 50, 100, 200 or 400 mg/liter N from 20N–8.6P–17K water soluble fertilizer applied daily in two, 45-minute irrigation events. At one-month intervals from June to October, seedlings were harvested, and dry weights and N content of leaves, stems and roots determined. In October, red oak dry weight increased up to 400 mg N/liter fertigation. Red maple dry weight was greatest between 200 and 400 mg N/liter fertigation. For both species, as N fertigation level increased, relative stem dry weight increased while relative root dry weight decreased. There was little change in relative leaf dry weight. For both species, percent N in leaf, stem and root tissues increased with increasing N fertigation. N distribution in leaf, stem and root tissues was similar to relative dry weight accumulation. Red maple plants had greater morphological adjustment to increasing N fertigation than did red oak plants. At the highest fertigation levels, red maple plants could be N loaded, increasing N tissue concentrations without an increase in plant dry weight. Red oak plants did not exhibit N loading.