抄録
Approaches and instrumentation are needed to collect data nondestructively that relate to the biomass, yield, and nutritious status of crop and plant communities. One approach is to relate spectral measurements on the plant canopies to their agronomic characteristics. But a spectroradiometer for scanning in the visible (400-700 nm) and near-infrared (750-2500 nm) wavelength intervals continuously in the outdoor is not available in Japan. Therefore, we designed, produced, and tested a semi-portable, computerized system for field use. In this paper we report on its design and present sample data. The instrument was a double beam system capable of measuring the reflectance from the canopy and skylight intensity simultaneously at the same wavelength over the interval 400-2200 nm (Figs. 1, 2 and 5). The scanning speed of the grating monochromator is 100 nm/min. A desktop computer (HP-9835) and changeable software control the calibration unit (standard white board), monochromator driver and A/D converters. The collected data are caluculated by the computer and saved on digital casette tape. A photomultiplier (400-900 nm) and a PbS photo-cell (900-2200 nm) are the detectors used. The field-of-view response is shown in Fig. 3, while changes in reflectance of a Kodak grey card with time of day at two wavelengths are shown in Fig. 8. Examples of crop canopy spectral profiles are presented in Fig. 6 and 7. Their patterns are similar to those in the literature for plant canopies.
