Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply
Optimizing the utilization of applied nitrogen (N) in fruit trees requires N supply that is temporally matched to tree demand. We investigated how the timing of N application affected uptake, allocation, and remobilization within 14-year-old “Gala”/M26 apple trees (Malus domestica Borkh) over two se...
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doaj-0c300674383d4cfb8ef62e9afdd7efa52021-05-31T08:26:39ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2021-05-011210.3389/fpls.2021.657070657070Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N SupplyBi Zheng TanDugald C. ClosePeter R. QuinNigel D. SwartsOptimizing the utilization of applied nitrogen (N) in fruit trees requires N supply that is temporally matched to tree demand. We investigated how the timing of N application affected uptake, allocation, and remobilization within 14-year-old “Gala”/M26 apple trees (Malus domestica Borkh) over two seasons. In the 2017–2018 season, 30 g N tree−1 of 5.5 atom% 15N–calcium nitrate was applied by weekly fertigation in four equal doses, commencing either 4 weeks after full bloom (WAFB) (pre-harvest) or 1-week post-harvest, or fortnightly, divided between pre- and post-harvest (50:50 split). Nitrogen uptake derived from fertilizer (NDF) was monitored by leaf sampling before whole trees were destructively harvested at dormancy of the first season to quantify N uptake and allocation and at fruit harvest of the second season to quantify the remobilization of NDF. The uptake efficiency of applied N fertilizer (NUpE) was significantly higher from pre-harvest (32.0%) than from the other treatments (~17%). The leaf NDF concentration, an indicator of N uptake, increased concomitantly only when pre-harvest N was applied. Pre-harvest treated trees allocated more than half of the NDF into fruit and leaves and stored the same amount of NDF into perennial organs as the post-harvest treatment. Subsequent spring remobilization of NDF was not affected by the timing of N fertigation from the previous season. A seasonal effect of remobilization was observed with a decrease in root N status and a reciprocal increase in branch N status at fruit harvest of season two. These findings represent a shift in the understanding of dynamics of N use in mature deciduous trees and indicate that current fertilizer strategies need to be adjusted from post-harvest to primarily pre-harvest N application to optimize N use efficiency. This approach can provide adequate storage N to support early spring growth the following season with no detriment to fruit quality.https://www.frontiersin.org/articles/10.3389/fpls.2021.657070/fullnitrogen use efficiency15Nremobilization (nitrogen)partitioning (nitrogen)application timingstorage (nitrogen) |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Bi Zheng Tan Dugald C. Close Peter R. Quin Nigel D. Swarts |
spellingShingle |
Bi Zheng Tan Dugald C. Close Peter R. Quin Nigel D. Swarts Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply Frontiers in Plant Science nitrogen use efficiency 15N remobilization (nitrogen) partitioning (nitrogen) application timing storage (nitrogen) |
author_facet |
Bi Zheng Tan Dugald C. Close Peter R. Quin Nigel D. Swarts |
author_sort |
Bi Zheng Tan |
title |
Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply |
title_short |
Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply |
title_full |
Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply |
title_fullStr |
Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply |
title_full_unstemmed |
Nitrogen Use Efficiency, Allocation, and Remobilization in Apple Trees: Uptake Is Optimized With Pre-harvest N Supply |
title_sort |
nitrogen use efficiency, allocation, and remobilization in apple trees: uptake is optimized with pre-harvest n supply |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Plant Science |
issn |
1664-462X |
publishDate |
2021-05-01 |
description |
Optimizing the utilization of applied nitrogen (N) in fruit trees requires N supply that is temporally matched to tree demand. We investigated how the timing of N application affected uptake, allocation, and remobilization within 14-year-old “Gala”/M26 apple trees (Malus domestica Borkh) over two seasons. In the 2017–2018 season, 30 g N tree−1 of 5.5 atom% 15N–calcium nitrate was applied by weekly fertigation in four equal doses, commencing either 4 weeks after full bloom (WAFB) (pre-harvest) or 1-week post-harvest, or fortnightly, divided between pre- and post-harvest (50:50 split). Nitrogen uptake derived from fertilizer (NDF) was monitored by leaf sampling before whole trees were destructively harvested at dormancy of the first season to quantify N uptake and allocation and at fruit harvest of the second season to quantify the remobilization of NDF. The uptake efficiency of applied N fertilizer (NUpE) was significantly higher from pre-harvest (32.0%) than from the other treatments (~17%). The leaf NDF concentration, an indicator of N uptake, increased concomitantly only when pre-harvest N was applied. Pre-harvest treated trees allocated more than half of the NDF into fruit and leaves and stored the same amount of NDF into perennial organs as the post-harvest treatment. Subsequent spring remobilization of NDF was not affected by the timing of N fertigation from the previous season. A seasonal effect of remobilization was observed with a decrease in root N status and a reciprocal increase in branch N status at fruit harvest of season two. These findings represent a shift in the understanding of dynamics of N use in mature deciduous trees and indicate that current fertilizer strategies need to be adjusted from post-harvest to primarily pre-harvest N application to optimize N use efficiency. This approach can provide adequate storage N to support early spring growth the following season with no detriment to fruit quality. |
topic |
nitrogen use efficiency 15N remobilization (nitrogen) partitioning (nitrogen) application timing storage (nitrogen) |
url |
https://www.frontiersin.org/articles/10.3389/fpls.2021.657070/full |
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