Autumnal nitrogen nutrition affects the C and N storage and architecture of young peach trees

Abstract

Nitrogen fertilisation is a regular practice in orchards. Its effect on tree development, N and C acquisition and allocation were evaluated simultaneously, while coupling on the same trees in situ measurements of N uptake and shoot development and destructive determinations of organ composition in N and Total Non structural Carbohydrates (TNC). An hydroponic set-up was designed that could grow young peach trees at constant NO 3 concentration while measuring N uptake. Forty-eight trees were raised outdoors under excessive N supply. Between October 2 and December 7, half of them were then N-limited to reduce N uptake by 75%. Organ N concentrations remained stable in the controls but were halved in N-limited trees. Growth (390 vs. 353 g DW tree -1 ) was less affected by the treatment than N uptake (10.6 vs. 2.7 g N tree -1 ). Growth was affected only in terms of axillary bud development, which was restricted to the median and upper crown parts. The number of buds which transformed into elongating axes (44 vs. 84 tree -1 ) was halved, thus reducing leaf area by one-third (10,464 vs. 15,568 cm 2 ). Tree TNC content was not impacted. The difference in C acquisition likely balanced the C costs of N uptake. In N-limited trees, more TNC was stored as starch (73 vs. 56%), and the allocation patterns of TNC and N were altered in favour of the roots. Our results provide deeper insights into the tree integrated response to autumnal N fertilisation, focusing on an alteration of the balance between storage and growth.

Autumnal N storage determines the spring growth, N uptake and N internal cycling of young peach trees

“…of leaf emergence), autumnal growth was restricted to axes thickening and root development, which are despite their importance (Niederholzer et al 2001;Kaelke and Dawson 2005) only little (Kubiske et al 1998;Dong et al 2005) or not (Niederholzer et al 2001;Jordan et al 2011) affected by soil N availability. We found no difference between treatments in terms of root and old axes DW (Fig.…”

“…This was probably the case in our study, because we had previously found values of between 2.6 and 3.3% DW in trees grown in similar conditions (Gomez and Jordan, unpublished). Uptake saturation may also be induced by the suppression of an important trophic sink: that relative to shoot elongation, which may represent up to 44% of the increase in autumnal biomass (Jordan et al 2011). However, these high values were obtained under exceptionally mild temperatures in young tree regrowing after severe late summer pruning.…”

“…Each C compound was computed separately to compare the treatments along with harvest dates. Each line represents a single test and means with the same letter are not significantly different increase significantly if shoot elongation continued late in autumn (Jordan et al 2011). N treatments affected N uptake and N accumulation in autumn and consequently N cycling in spring (Fig.…”

Nitrogen fertilization rates in a subtropical peach orchard: effects on tree vigor and fruit quality

“…Stored N is mobilized from the roots at the beginning of the growing season and used in the development of flowers and new vegetative growth . At the end of the season, leaf N is remobilized to storage organs for use in the following season; these events are part of the N cycle in woody plants . However, stored and available soil N may not be sufficient to produce a profitable yield, necessitating application of N‐based fertilizers …”

<b>Nutritional status, yield and composition of peach fruit subjected to the application of organic compost

“…In addition, increases in the yield components, such as fruit weight and diameter, which reflect greater fruit yields per plant and per hectare are expected along with impacts on fruit composition, which determine the storage period after harvest (Falguera et al, 2012). Nevertheless, the mineralization of compost in the soil will determine the responses of the peach trees and depends on the composition of the compost, including the nutrient content and C/N ratio (Jordan et al, 2011;Sofo et al, 2005). The amount of compost applied to the surface will determine the contact area with the ground, which can slow the activity of the microbial biomass (Ramos, Benítez, García, & Robles, 2011) and affect the soil moisture and soil temperature (Montanaro, Dichio, Bati, & Xiloyannis, 2012).…”