Photon Systems Instruments PlantPen NDVI 310, Manual And User Manual

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© PSI (Photon Systems Instruments), spol. s r. o.
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6 PRINCIPLE OF MEASUREMENT
PlantPen is a reflectance-based device that provides a convenient method of measuring the relative chlorophyll content
of a leaf sample.
The PlantPen model PRI 210 (Fig. 2)measures Photochemical Reflectance Index (PRI) by comparing leaf reflectance in two
narrow wavelength bands centered close to 531 nm and 570 nm. PRI is sensitive to changes in carotenoid pigments that
are indicative of changes in photosynthetic light use efficiency, the rate of CO
2
uptake and as a reliable water-stress index.
As such, it is used in studies of vegetation productivity and stress.
Fig. 2 PlantPen PRI 210.
The PlantPen model NDVI 310 (Fig. 3) measures Normalized Difference Vegetation Index (NDVI) , which is an important
indicator of chlorophyll content in plants. The pigment in plant leaves, chlorophyll, strongly absorbs visible light (from 0.4
to 0.7 µm) for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near -infrared
light (from 0.7 to 1.1 µm). The differences in plant reflectance in the visible and near -infrared wavelengths are used to
calculate NDVI index. NDVI is directly related to the photosynthetic capacity and hence energy absorption of plant
canopies.
Fig. 3 PlantPen NDVI 310.