title: The early spring N uptake of young peach trees (Prunus persica) is affected by past and current fertilizations and levels of C and N stores.
abstract: In deciduous trees, shoot development in early spring is assumed to be achieved mainly at the expense of nitrogen (N) stores. Indeed, the possible compensation for poor autumn N storage by early spring N uptake has been little studied. We therefore determined the dynamics of spring N uptake in relation to spring N supply, carbon and N storage and shoot development. Young peach trees (Prunus persica L. Batsch, cv. 'GF305') were raised outdoors in a hydroponic set-up during the spring and summer, with an excessive N supply. During the autumn, half of the trees were then N limited. The following spring, the N supply remained either high or low, or changed from high to low or low to high. Between 6 March and 13 May, N uptake was measured automatically on an hourly basis, while shoot growth was monitored once a week. These in situ measurements were completed by three destructive harvests to assess organ composition in N and total non-structural carbohydrates (TNC). Until the end of April, N uptake was dependent on the autumn N treatment, being higher in trees that had been N limited in the autumn. Total non-structural carbohydrate mobilization was also higher in those trees that had lost at least 17 g TNC by 24 April, while TNC levels in non-limited trees remained stable or even rose. Shoot development, estimated by the number of elongated axes and leaves per axis, was also slightly delayed by an N limitation in autumn. After 24 April, N uptake rates increased notably under all treatments and was determined by the spring N supply. In trees receiving a high N supply in the spring, the uptake rates also displayed marked short-term variations. That reduced the differences between treatments and by 13 May no differences could be evidenced between the trees in terms of organ biomass and TNC and N contents, whatever the treatment. We concluded that in the early spring, N uptake may compensate for a deficit of N storage insofar as large quantities of TNC can be mobilized for that purpose.
authors.affiliation: UR 1115 Plantes et Systèmes de culture Horticoles (PSH), Domaine Saint-Paul, INRA, 228 route de l'Aérodrome, CS 40509, F-84914 Avignon Cedex 9, France;
authors.forename: Marie-Odile
authors.initials: MO
authors.lastname: Jordan
authors.forename: Gilles
authors.initials: G
authors.lastname: Vercambre
authors.forename: Laurent
authors.initials: L
authors.lastname: Gomez
authors.forename: Loïc
authors.initials: L
authors.lastname: Pagès
mesh_terms: D018533:Biomass; D002241:Carbohydrates / Q000032:analysis; D002244:Carbon / Q000378:metabolism*; D005308:Fertilizers; D005602:France; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D027861:Prunus / Q000254:growth & development / Q000378:metabolism*; D012621:Seasons; D014197:Trees
chemical_list: D002241:Carbohydrates; D005308:Fertilizers; D002244:Carbon; D009584:Nitrogen
keywords: bud burst; nitrogen allocation; nitrogen fertilization; non-structural carbohydrate; shoot development