© 1998 Heron Publishing—Victoria, Canada
Storage of foliar-absorbed nitrogen and remobilization for spring growth in young nectarine (Prunus persica var. nectarina) trees
M. Tagliavini (1), P. Millard (2) and M. Quartieri (1)
1. Dipartimento di Colture Arboree, Universitá di Bologna, Via F. Re 6, 40126 Bologna, Italy / 2. Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH, U.K. / Received June 23, 1997
Summary
The effectiveness of spraying foliage with urea to provide nitrogen (N) to augment the seasonal internal cycling of N in young
nectarine trees (Prunus persica (L.) Batsch var. nectarina (Ait. f. Maxim.), cv. Stark Red Gold) was studied. One-year-old trees were grown with contrasting N supplies during the summer
and foliage was sprayed with a 2% urea solution labeled with 15N just before leaf senescence started. After leaf abscission had finished, the trees were repotted in sand and given no further
N. Remobilization of both labeled and unlabeled N for leaf growth the following spring was quantified.
Leaves absorbed between 58 and 69% of the 15N intercepted by the canopy irrespective of tree N status. During leaf senescence, the majority of 15N was withdrawn from the leaves into the shoot and roots. Remobilization of 15N the following spring was also unaffected by tree N status. About 38–46% of 15N in the trees was recovered in the new growth. More unlabeled N (derived from root uptake) was remobilized for leaf growth
in the spring than was withdrawn from leaves during canopy senescence the previous autumn. Therefore, soil-applied N augmented
N storage pools directly, and contributed more to N remobilization the following spring than did foliar-absorbed 15N.
Keywords:
foliar urea sprays, internal cycling, leaf growth, peach, root uptake.
