ISHS Acta Horticulturae 465: IV International Peach Symposium
STORAGE AND REMOBILISATION OF NITROGEN IN NECTARINE TREES IS AFFECTED BY THE TIMING OF N UPTAKE |
| Authors: | M. Quartieri, M. Tagliavini, B. Marangoni, P. Millard |
| Keywords: | internal cycling, nitrogen remobilisation, nitrogen storage, nitrogen uptake, Peach, Prunus persica |
| Abstract:
In spring, peach trees use nitrogen (N) previously stored in perennial organs to sustain their early growth. We have tested the hypothesis that the timing of N uptake affects such internal cycling of N. For this purpose, 6 nectarine trees, cv. Starkredgold grafted on GF305 and planted in pots filled with a sandy soil received five fertigations from mid May to mid July (1.0 g N/tree) with urea labelled with 3.6 atom % 15N (TRT A - early uptake), while another set of similar trees (TRT B - late uptake) received the same amount of N as unlabelled urea. In mid August, all pots were heavily watered until no nitrate N was detected in the leaching; then the trees belonging to TRT B received 5 fertigations (at 15-day intervals) with the labelled urea (1.0 g N/tree), while those of TRT A received unlabelled N. Before leaf senescence started, the tree canopies were covered in a net and all abscised leaves collected. In winter, some of the trees were harvested and divided into main organs. The remaining trees were transplanted into similar pots filled with pure sand and were harvested in May. Results indicate that peach trees took up similar amounts of N in the early and in the late period, close to 50% of that distributed. However, more labelled nitrogen was recovered in the perennial organs in winter in TRT B than in TRT A. About 35% of the N taken up in the early period was detected in the abscised leaves, the corresponding percentage for late uptake being only 10%. In winter some 73–80% of the N present in the tree was stored in the roots which contained almost twice the amount of labelled N taken up late than that absorbed early. Nitrogen for spring growth was remobilised predominantly from the roots and accounted for some 43–49% of the labelled N recovered in the tree during winter. Results suggest that the nitrogen taken up late in the season is preferentially stored at root level and is used by peach trees to sustain new growth the following spring. | |
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