In-field proximal sensing of most major crops nutrients still remains an economical and technical challenge. For this purpose, the use of effective multi-excitation fluorescence and reflectance wavelengths is explored...In-field proximal sensing of most major crops nutrients still remains an economical and technical challenge. For this purpose, the use of effective multi-excitation fluorescence and reflectance wavelengths is explored in this work on Okra plant. Visible-near infrared (400 - 1000 nm) reflectance and multi-fluorescence data were collected at leaf scale in a chemically fertilized field by using an USB spectrometer mounted with an Arduino-based LED driver clip. N, P, K and Ca content of samples leaves were measured using reference methods. Average pods yield and leaves macronutrients content were calibrated using IRIV-PLS regression after spectra pretreatments. Single informative wavelengths bands in reflectance, red and far-red fluorescences were selected for building yield and macronutrient content models. We showed that flowering stage was more suitable for yield prediction. Moderately useful macronutrient models were found in Ca content (RPDval = 1.93, rP = 0.818) and potassium content with RPDval = 1.8, rP = 0.88. P and N yielding prediction performance of RPDval = 1.61 (rP = 0.718 ) and RPDval = 1.46 (rP = 0.56) respectively were less accurate. This study demonstrates potentiality of fluorescence and reflectance spectroscopy for accurate estimation of leaf macronutrient content and crop yield. High selectivity obtained from resulted spectral bands could lead to the development of reliable, rapid and cost-effective devices for nutrient diagnosis.展开更多
Absorbance measurement in dense media via conventional optical spectroscopy techniques leads to inaccurate results. This is mainly due to multiple scattering phenomena that contribute to the overall light extinction i...Absorbance measurement in dense media via conventional optical spectroscopy techniques leads to inaccurate results. This is mainly due to multiple scattering phenomena that contribute to the overall light extinction in the interrogated sample. This limitation imposes the use of dilute solutions for absorption spectroscopy. However, depending on the polarity of the solvent used, the absorption spectrum may vary over a given solution. Structured illumination technique offers an alternative to this problem, and provides the ability to calculate in-situ optical properties in dense media. In this paper, we propose two processing methods applied to images acquired by structured laser illumination planar imaging (SLIPI) technique to extract extinction coefficients μ_e of probed solutions: The first is based on the implementation of principal component analysis (PCA) and the second, on the calculation of Mean Value. In practice, two kinds of studies were carried out: one quantitative set of measurements within chlorophyll liquid solutions and a second set with concentrated coffee solutions, with controlled proportion and concentrations for each sample. These two proposed analytical techniques are advantageous because they are very easy to implement and provide a much simpler alternative to the previous one. Both methods offer satisfactory results, similar to those obtained with the original method which is based on 1D Fourier transform.展开更多
文摘In-field proximal sensing of most major crops nutrients still remains an economical and technical challenge. For this purpose, the use of effective multi-excitation fluorescence and reflectance wavelengths is explored in this work on Okra plant. Visible-near infrared (400 - 1000 nm) reflectance and multi-fluorescence data were collected at leaf scale in a chemically fertilized field by using an USB spectrometer mounted with an Arduino-based LED driver clip. N, P, K and Ca content of samples leaves were measured using reference methods. Average pods yield and leaves macronutrients content were calibrated using IRIV-PLS regression after spectra pretreatments. Single informative wavelengths bands in reflectance, red and far-red fluorescences were selected for building yield and macronutrient content models. We showed that flowering stage was more suitable for yield prediction. Moderately useful macronutrient models were found in Ca content (RPDval = 1.93, rP = 0.818) and potassium content with RPDval = 1.8, rP = 0.88. P and N yielding prediction performance of RPDval = 1.61 (rP = 0.718 ) and RPDval = 1.46 (rP = 0.56) respectively were less accurate. This study demonstrates potentiality of fluorescence and reflectance spectroscopy for accurate estimation of leaf macronutrient content and crop yield. High selectivity obtained from resulted spectral bands could lead to the development of reliable, rapid and cost-effective devices for nutrient diagnosis.
文摘Absorbance measurement in dense media via conventional optical spectroscopy techniques leads to inaccurate results. This is mainly due to multiple scattering phenomena that contribute to the overall light extinction in the interrogated sample. This limitation imposes the use of dilute solutions for absorption spectroscopy. However, depending on the polarity of the solvent used, the absorption spectrum may vary over a given solution. Structured illumination technique offers an alternative to this problem, and provides the ability to calculate in-situ optical properties in dense media. In this paper, we propose two processing methods applied to images acquired by structured laser illumination planar imaging (SLIPI) technique to extract extinction coefficients μ_e of probed solutions: The first is based on the implementation of principal component analysis (PCA) and the second, on the calculation of Mean Value. In practice, two kinds of studies were carried out: one quantitative set of measurements within chlorophyll liquid solutions and a second set with concentrated coffee solutions, with controlled proportion and concentrations for each sample. These two proposed analytical techniques are advantageous because they are very easy to implement and provide a much simpler alternative to the previous one. Both methods offer satisfactory results, similar to those obtained with the original method which is based on 1D Fourier transform.
