A feasibility study on assessing nitrogen content in maize organs using Fourier transform infrared spectroscopy
It is important to study the feasibility of using Fourier transform infrared spectroscopy(FTIR)to evaluate the nitrogen(N)content in crop organs rapidly and optimize N fertilizer management.In this study,hydroponic experiments were carried out on maize using humic acid with low molecular weight(HA1)and high molecular weight(HA2)as fertilizers.By setting different concentrations of HA1 and HA2,plant samples with significant differences in organ N content in the short term were obtained.On the basis of measur-ing/collecting the N content and FTIR spectra of different maize organs,the relationship between the N content and the absorbance at the specific wave number of FTIR was investigated by principal component analysis(PCA),and the FTIR characteristic parameters for the evaluation of N content in maize samples were deter-mined.The result showed that:(1)The effects of different concentrations of HA1 and HA2 on the N content of various maize organs were distinguishable.At a concentration of 2.5 mg·L-1,HA1 significantly increased the N content of leaves,stems,and roots(P<0.05)by 20.8%,19.9%,and 64.2%,respectively,as compared to the control.However,as the HA1 concentration increased,the N content of each organ showed a downward trend.When the HA1 concentration reached 25 mg·L-1,the N content of all organs was lower than the control.On the other hand,HA2 generally increased the N content of all organs,with a significant increase by 35.0%-45.4%in the roots(P<0.05).(2)The impact of varying concentrations of HA1 and HA2 on the absorption of FTIR at different wave numbers(1 051.0,1 159.0,1 247.7,1 635.3,1 650.8,1 731.8 and 2 919.7 cm-1)in different organs mirrored their effects on N content.In other words,higher concentrations of HA2 and low concentrations of HA1 could increase the contents of organic components,such as proteins,lipids,and carbohydrates in maize organs.(3)The results of principal component analysis revealed that the three characteristic wavenumbers were highly correlated with N con-tent,1 635.3,1 247.7 and 1 159.0 cm-1 for the leaves,1 650.8,1 159.0 and 1 247.7 cm-1 for the stems,and 1 635.3,1 650.8 and 1 159.0 cm-1 for the roots.Therefore,the absorbance of FTIR at these wavenumbers can be utilized to assess the N content in maize samples,with higher absorbance indicating a higher N content.By comparing the FTIR absorbance at specific wave numbers in different organs of maize,the effects of different agricultural measures on the N content of maize organs can be preliminarily evaluated.The result provides an important ref-erence for the future application of FTIR in the diagnosis of plant N nutrition.
国家科技期刊平台
NSTL
万方数据
