Threshold Effects of Nitrogen Fertilization Rates on Growth and Essential Oil Yield with Component Regulation in <i>Cinnamomum camphora</i> var. <i>linaloolifera</i>
The determination of an optimal nitrogen (N) fertilization rate is critical for the sustainable large-scale cultivation of <i>Cinnamomum camphora</i> var. <i>linaloolifera</i> for essential oil production. Both suboptimal and excessive nitrogen inputs can adversely affect pla...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Agronomy |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4395/15/6/1387 |
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| Summary: | The determination of an optimal nitrogen (N) fertilization rate is critical for the sustainable large-scale cultivation of <i>Cinnamomum camphora</i> var. <i>linaloolifera</i> for essential oil production. Both suboptimal and excessive nitrogen inputs can adversely affect plant sustainable development and essential oil biosynthesis, underscoring the necessity of precise nutrient management. This study investigated the effects of five N application rates (0, 45, 90, 135, and 180 kg·hm<sup>−2</sup>) on vegetative growth, essential oil yield, and quality. Growth parameters, including plant height, basal diameter, specific leaf area (SLA), and essential oil yield and yield rate. Oil composition was characterized via gas chromatography–mass spectrometry (GC-MS). The application of 90 kg·hm<sup>−2</sup> N significantly enhanced plant height (74.31%), basal diameter (54.95%), SLA (20.91%), and biomass (181.8%) relative to the nitrogen-free control. Nitrogen uptake was concentrated in foliar tissues, accounting for 82.8% of total plant nitrogen accumulation. This fertilization rate also maximized essential oil yield (9.15 g·plant<sup>−1</sup>) and yield rate (2.44%), reflecting increases of 178.9% and 24.49%, respectively. Linalool was the predominant oil constituent (89.84–91.81%), with its highest concentration observed at the 90 kg·hm<sup>−2</sup> treatment. At this rate, the relative abundance of oxygenated compounds increased by 0.97%, while hydrocarbon content decreased by 0.62%, indicating a qualitative improvement in oil composition. The findings reveal a threshold response to nitrogen input, wherein rates exceeding 90 kg·hm<sup>−2</sup> did not confer further benefits and may reduce efficiency. Collectively, these results suggest that a nitrogen application rate of 90 kg·hm<sup>−2</sup> optimally enhances vegetative growth, nitrogen assimilation, and both the quantitative and qualitative traits of essential oils in <i>C. camphora</i> var. <i>linaloolifera</i>. |
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| ISSN: | 2073-4395 |