SPECTROSCOPY
GPC across a fi eld. Development of the chemometric calibration model began with a three-year fi eld study to obtain grain samples of soft white wheat grown under a variety of nitrogen and water level conditions. Custom code interfaces to import Avantes AvaSoft data into DeLight spectroscopic software where a process called binning grouped spectra into 126 bands of 16 pixels, a smoothing technique that simplifi es a set of variables for modelling. Binning increases the signal to noise ratio while sacrifi cing resolution, in this case the resolution was reduced to 11.2nm, which kept resolution within acceptable limits. T e application of the second derivative removed baseline shifts caused by the random orientation of grains. And fi nally, DeLight used partial least squares to fi nd wavelength regions of interest where the grain sample was the independent variable and GPC as the dependent variable and derive a calibration model for grain protein concentration.
RESULTS T e resulting maps of GPC and grain yield demonstrated the inverse relationship between yield and protein content indicative of moisture-limited environments. Low yield area corresponds to thin unproductive soils where increased nitrogen fertiliser has little benefi t. T e protein map derived from the USDA test system was comparable to one created using a much more expensive Polytec spectrometer system. Predictive models from local samples are limited in data, but the use of machine learning or artifi cial neural networks can increase system accuracy, but even so, not many farmers have the luxury of time to learn to apply advanced chemometric analysis. Adoption of this technology could be dependent on the availability of commercial services for chemometric modelling.
An adapted AvaSpec spectrometer was used for the grain project
T e fi nal result of this study was
proof of the potential for moderately priced alternatives to costly (>US$20,000) combine-mounted spectral mapping systems.
Janel Kane is with Avantes.
www.avantes.com
DECEMBER 2020
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www.scientistlive.com MICROSCOPY
SUPER-RESOLUTION What are its applications?
ANALYSIS Automation
INNOVATIONS Healthcare
www.scientistlive.com 31
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