Spatial-temporal management of nitrogen and carbon on the peach tree (Prunus persicae L. Batsch.)

In perennial plants, the management of nitrogen (N) and carbon (C) is crucial to their durability, and studies encompassing an integrative viewpoint on the dynamics, location and form of the reserves are still missing. The carbon and nitrogen components were measured from September to May in peach trees which received two different levels of N fertilisation (control and limited). Significant differences were observed in the N and nonstructural carbon concentrations regarding the organs, locations, time and fertilisation level. During the autumn, N and C accumulate at all levels of the tree and are sharply remobilised for the spring growth resumption. Amino acids (AA), especially arginine, appear to be the main form of storage of N. More present in roots, short branches and apices, the AA reach their maximum concentration in February and drop sharply with bud development. The remobilisation of the AA is initially induced in the branches close to the aboveground plant parts structures in formation, and before the contribution of the roots pool. The non-structural carbon (starch, soluble sugars, and organic acids) also accumulate during the autumn. No major differences are observed in the position and the size of the branches. The starch present in the root is the main form of carbon reserve of the peach tree. The starch stocks decline very early in November and are then gradually restored while the tree becomes autotrophic in the spring. The deprivation of N essentially caused a significant decrease in the stocks of AA and erased the differences in concentrations found in relation to the typology of branches. So the tree modified its N management strategy in response to the fertilisation level. The concentration of arginine, the main amino acid present in the bark or in the roots, appears as a relevant marker of its N status.