© 1998 Heron Publishing—Victoria, Canada
Nutrient enrichment of white spruce seedlings during nursery culture and initial plantation establishment
J. A. McAlister (1) and V. R. Timmer (1)
1. Faculty of Forestry, University of Toronto, 33 Willcocks Street, Toronto, Ontario M5S 3B3, Canada / Received March 7, 1997
Summary
Growth and nutrient dynamics of bare-root white spruce (Picea glauca (Moench) Voss) seedlings were monitored for three years in a nursery and for one season after planting to assess effects
of three nursery fertilization regimes. Nitrogen (totaling 0, 650, and 1300 kg N ha–1 for 3 years) was applied conventionally in equal amounts during the growing season. The high-N treatment, representing a
nutrient loading regime, was also applied seasonally at exponentially increasing rates as a fourth treatment. By the end of
the 3-year nursery rotation, the N treatments had stimulated growth by 104–180% and nutrient uptake by as much as 381, 224
and 145% for N, P and K, respectively, inducing large accumulations of N and P in both conventionally and exponentially loaded
seedlings. Compared with exponentially loaded seedlings, the concentrations of nutrients were less in conventionally loaded
seedlings although their biomass was larger (31%). High nutrient reserves in the seedlings at the end of the nursery rotation
resulted in increased biomass production (40–190%) after planting, which was related to the ability of the seedlings to retranslocate
internal reserves for new growth, despite little or no net uptake of nutrients during the first season after planting. Compared
with conventionally loaded seedlings, retranslocation was greater in exponentially loaded seedlings, which had accumulated
larger and more readily available nutrient reserves during the nursery phase. The shortness of this study limits its usefulness
for predicting the persistence of the loading response after planting, but we postulate that the high nutrient status of loaded
seedlings at the end of the nursery rotation will contribute to future growth through increased nutrient storage and retranslocation,
thus prolonging the loading response.
Keywords:
exponential fertilization, nutrient loading, retranslocation, seedling nutrition, transplanting check.
