Nitrogen Use Efficiency of Drip-Irrigated ´rocha´ Pear Trees

Abstract

Synchronizing the availability of N in the rhizosphere with its uptake pattern by the trees throughout the vegetative cycle enhances the efficiency of its use. This study aimed to: i) quantify the N use efficiency in the non-bearing pear trees, fertigated with 15 N and ii) identify the pear tree N storage organs and access the distribution of N derived from the fertilizer (NDFF) in the organs. One-year old pear trees (Pyrus communis cv. Rocha on quince BA29 rootstock) planted in a loamy sand soil at 4 m x 1.5 m spacing, were supplied from April to October with 6 g N tree-1 of ammonium nitrate, doubled labeled with 5 atom% of 15 N. Leaf samples were monthly collected to determine %NDFF. At the beginning of leaf fall five trees were wrapped with nets and all abscised leaves were collected. At the end of leaf fall trees were removed from the soil and divided into fine and coarse roots, trunk and shoots. Each plant sample was weighed and analyzed for total N and 15 N abundance. The trunk was the main storage organ of the tree (44.5% of the total N), followed by the coarse roots (24.8%). 15 N enrichment was greater in the trunk (0.18 g tree-1), which represented 47.3% of the total 15 N recovered in the tree tissues. Senescent leaves showed the lowest %NDFF, retaining 6.2% of the absorbed N, which represented 9.6% of the tree 15 N enrichment. After the first year of N fertigation, newly-planted 'Rocha' pear trees showed a low N-fertilizer use efficiency (6.3%) possibly due to the lower N uptake during the initial three months after planting.

Optimizing Nitrogen Application for Growth and Productivity of Pomegranates

“…The different N levels gave distinct results each year, with greater diversity between the treatments in 2017 and 2018, in which the trees bore fruit. The partial factor productivity of applied N (PFP), which is a N efficiency index [44], was found to be synchronized with the annual growth of pear trees and highly correlated with N availability in the root zone [45]. However, in our experiment, N availability was consistently high due to the soilless media and excessive irrigation; hence, growth cycle had a greater impact over this parameter.…”

DISTRIBUTION AND RECYCLING OF CANOPY NITROGEN STORAGE RESERVES IN SWEET CHERRY (Prunus avium) FRUITING BRANCHES FOLLOWING 15N-UREA FOLIAR APPLICATIONS AFTER HARVEST

“…In peach trees (P. persica L.), Nario et al (2003) reported a NUE of 12.7% for soil applications during the summer. However, Neto et al (2006) reported a NUE of 6.3% after N soil applications in pear trees. These authors used 15 N as a tracer, and the trees were analyzed during dormancy.…”

Examining growth, yield and bean quality of Ethiopian coffee trees : towards optimizing resources and tree management

“…Fenilli et al (2007); (2008); ); as well as values reported for other tree crops (e.g. young pear (Neto et al 2006) and peach (Nario et al 2003)). The continued response of coffee trees to increase in N supply, coupled with low ANR, is probably the main reason why high N rates (e.g.…”

“…tree species low ANRs were reported, e.g. 6.3 % for young pear (Neto et al 2006) and 8.3 -12.7 % for peach (Nario et al 2003). This raises the question as to why such low values may occur.…”

“…This raises the question as to why such low values may occur. One aspect is perhaps that N immobilization is rapid in tropical environments (Dourado-Neto et al 2010), probably resulting in more N to be preserved in soil colloidal material (Bruno et al 2014;Moreira et al 2006), or perhaps due to slow process of root growth that are observed in most young plants (Neto et al 2006;Neto and Matsumoto 2010).…”