Retranslocation, Plant, and Soil Recovery of Nitrogen-15 Applied to Bareroot Black Walnut Seedlings
Although retranslocation or nitrogen (N) derived from plants (NDFP) may account for more than 50% of the annual N demand in new growth of conifer seedlings, the proportional contribution of NDFP vs. current uptake or N derived from fertilizer (NDFF) in new growth of hardwood seedlings
is relatively unknown. The current uptake was labeled with ammonium sulfate [(15NH4)2SO4] at the rate of 1.56 g N plant-1 and reared for 90 days in sand culture under greenhouse conditions, and NDFP vs. NDFF was quantified in new growth of half-sib bareroot black walnut (Juglans
nigra L.) seedlings. Nitrogen derived from plants accounted for 68 to 83% of the total N demand in new shoot growth of black walnut seedlings vs. NDFF (17 to 32%). Recovered applied fertilizer was 43% in soil and 9% in plants. The greater proportion of NDFP in new growth demonstrates the importance
of retranslocation in meeting early N demand of transplanted black walnut seedlings.
Keywords: Black walnut; fertilizer recovery; growth; nitrogen; retranslocation; stable isotope
Document Type: Research Article
Affiliations: Department of Forestry and Natural Resources, Hardwood Tree Improvement and Regeneration Center, Purdue University, West Lafayette, Indiana, USA
Publication date: 01 May 2009
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