Portable system approach of monitoring plant nutrient deficiency using fiber optic spectrophotometry

In this paper, a portable sensing system is developed using fiber optic spectroscopy principle for measuring and detecting of stresses induced in plants due to nutrient deficiencies. Chlorophyll fluorescence in plants is used to monitor the effects of nutrient stress in plants. As this method aims at providing an early detection and warning of nutrient deficiencies, it gives an alternative to argument current semi-quantitative and destructive methods of nutrient analysis. Our early papers had demonstrated significant differences in the color reflectance of plants' leaves when plants were subjected to various nutrient- deficient media. Developed using off-the-shelf components, this digital sensing optical system could measure and detect the slight variation in the plants' reflectance and hence its chlorophyll levels. These relative levels of chlorophyll are determined by measuring the plants' color reflectance of light while using the wavelength of the healthy plants as a reference for comparison. This system comprises of a miniature spectrometer containing 1024 CCD detectors covering a visible light spectrum of wavelength ranging from approximately 400 nm to 800 nm and a reflective probe. A laptop with a PCMCIA A/D data acquisition card is used in conjunction with a customized program.