Diagnosis of nitrogen status in Chinese cabbage (Brassica rapa chinensis) using the ratio of amide II to amide I in leaves based on mid‐infrared photoacoustic spectroscopy |
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Authors: | Chunyang Li Changwen Du Fei Ma Jianmin Zhou |
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Institution: | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China |
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Abstract: | In order to quickly diagnose the nitrogen status of Chinese cabbage (Brassica rapa chinensis), Fourier transform mid‐infrared photoacoustic spectroscopy, a nondestructive and rapid approach was used. Two clear stable peaks, in the range 1680–1650 cm?1 associated with amide I and in the range of 1530–1520 cm?1 associated with amide II, were observed and responded positively to nitrogen treatments. The characteristic bands of amide I and amide II were also accurately separated by curve‐fitting via deconvolution using a Gauss expansion function. The ratio of the photoacoustic intensities of amide II to amide I was used for correlation analysis with nitrogen treatment, and the correlation coefficients (R2, n = 59) at seedling and growth stage were 0.9769 (P ≤ 5%) and 0.9884 (P ≤ 5%), respectively. The ratio of the amide II and amide I peaks was found to be an indicator of nitrogen input during the seedling stage such that a ratio of less than 0.9 indicated a low nitrogen input, a ratio between 0.9 and 1.0 indicated a moderate nitrogen input, and a ratio of more than 1.0 implied an excessive N input. |
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Keywords: | Fourier transform mid‐infrared photoacoustic spectroscopy leaf vegetables nitrate nitrogen diagnosis |
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