Effect of Fertilization Timing on Nitrogen Uptake in Spring Tea of Different Sprouting Phenological Cultivars: A Field Trial with <sup>15</sup>N Tracing
Applying a top dressing of nitrogen fertilizer before harvesting spring tea is vital for producing high-quality spring tea. However, the interaction between the sprouting phenological characteristics of various cultivars and the timing of top dressing remains unclear. A field trial was conducted to...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Agronomy |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4395/15/5/1090 |
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| Summary: | Applying a top dressing of nitrogen fertilizer before harvesting spring tea is vital for producing high-quality spring tea. However, the interaction between the sprouting phenological characteristics of various cultivars and the timing of top dressing remains unclear. A field trial was conducted to investigate such interaction. Urea enriched with <sup>15</sup>N was applied to soil of the early-sprouting cultivar Jia-ming-1 (JM1) and the late-sprouting cultivar Tie-guan-yin (TGY) on 29 January (early application, EApp) or 10 March (late application, LApp), respectively. The bud density and yield of young spring shoots were significantly decreased in LApp compared to EApp. Such differences were more remarkable in the early-sprouting cultivar (JM1) than in the late-sprouting cultivar (TGY). The N<sub>dff</sub> (N derived from <sup>15</sup>N-enriched urea) in mature leaves and young spring shoots as well as the amount of <sup>15</sup>N in young spring shoots were all higher in EApp than in LApp. N<sub>dff</sub> in both mature leaves (<i>R</i><sup>2</sup> = 0.99, <i>p</i> < 0.001) and young spring shoots (<i>R</i><sup>2</sup> = 0.61–0.89, <i>p</i> < 0.01) could be well predicted by the growing degree days of the duration between the N fertilization and sampling. N<sub>dff</sub> and <sup>15</sup>N concentrations in mature leaves were significantly correlated with the content of nitrate and the ratio of ammonium to total inorganic nitrogen. Partial least squares path modeling revealed that thermal condition directly affected soil N supply and soil pH and thereby affected N<sub>dff</sub> in mature leaves and young spring shoots. Our findings highlight the importance of early pre-spring topdressing of N fertilizer to improve the yield and N use efficiency of spring tea in both early- and late-sprouting tea cultivars. The work identified a synergistic effect of N uptake by tea plants, N transformation, and soil pH related to the thermo-conditions of early and late N topdressing. |
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| ISSN: | 2073-4395 |