Development of a portable spectroscopy-based device to detect nutrient status of apple tree

In order to detect apple tree growth status fast and accurately, four sensitive wavebands (364nm, 652nm, 766nm, 810nm) were obtained by analyzing the correlation between the apple leaves spectra and their nitrogen contents plus adopting the segment reduced precise sampling methods. A rapid determination model of apple leaf nitrogen content suitable for portable detector was built. Then a portable spectroscopy-based device was developed. It consists of an optical unit and a control unit. The optical channel was consisted of convex lens, optical filter, photoelectric detector and airtight mechanical exine. The optical unit was used to capture, transit, transform and submit the optical signal. The controller was consisted of operation, input, display, data storage and power control unit adopting JN5139 as main control unit. Controller was the coordinator in building the wireless network. And it was also responsible for receiving the measured data from sensor, calculating vegetation index, and displaying and storing the calculated results. The experiments showed that the correlation coefficient between the measured nitrogen content and the predicted nitrogen content reached to 0.857. It illustrated that the apple tree nitrogen detector was practical and could be used to detect leaf nitrogen content in apple orchard.