User manual MINOLTA SPAD-502 BROCHURE

[. . . ] CHLOROPHYLL METER SPAD-502 A lightweight handheld meter for measuring the chlorophyll content of leaves without causing damage to plants. The SPAD-502 is a compact meter designed to help users improve crop quality and increase crop yield by providing an indication of the amount of chlorophyll present in plant leaves. The chlorophyll content of plant leaves is related to the condition of the plant, and thus can be used to determine when additional fertilizer is necessary. [. . . ] One set of two AA-size alkaline-manganese batteries can provide approximately 20, 000 measurements. Small measuring area The measuring area is only 2 × 3mm, allowing measurements of even small leaves. A sliding depth stop is included for accurate positioning of sample leaves. High accuracy High measuring accuracy (± 1. 0 SPAD unit for rice-plant leaves) allows close examination of growing conditions. Data memory The SPAD-502 has memory space for 30 measurements. Data in memory can be recalled or deleted at a later time, and the average value of all data in memory can be automatically calculated. Reading checker A reading checker enables users to check that the SPAD502 is functioning correctly and providing accurate readings. Theory The SPAD-502 determines the relative amount of chlorophyll present by measuring the absorbance of the leaf in two wavelength regions. The graph at right shows the spectral absorbance of chlorophyll extracted from two leaf samples using 80% acetone. From the diagram, it can be seen that chlorophyll has absorbance peaks in the blue (400-500nm) and red (600-700nm) regions, with no transmittance in the near-infrared region. To take advantage of this characteristic of chlorophyll, the SPAD-502 measures the absorbances of the leaf in the red and near-infrared regions. [. . . ] For example, it was determined from past experience that for Sasanishiki rice plants a SPAD value of 35 or above was desirable to produce a target yield of 600kg/10a. During the differentiation and formation of ears, a period of rapid plant development, the SPAD value fell to between 29 and 32, indicating that additional fertilizer was necessary. SPECIFICATIONS Type: Handheld meter for measuring chlorophyll using optical density difference at two wavelengths Measurement sample: Crop leaves Measurement system: Optical density difference at two wavelengths Measurement area: 2 × 3mm Light source: 2 LEDs (light-emitting diodes) Receptor: 1 SPD (silicon photodiode) Display: Measurement data: 3-digit LCD with decimal point Data number: 2-digit LCD Data memory: Space for 30 data sets Controls: Power switch, AVERAGE key, ALL DATA DELETE key, ONE DATA DELETE key, and DATA RECALL key Power source: 2 AA-size alkaline-manganese (1. 5V) batteries Battery line: More than 20, 000 measurements Minimum interval between measurements: Less than 2 seconds Accuracy: Within ± 1. 0 SPAD unit (at room conditions, SPAD value between 0 and 50) Repeatability: Within ± 0. 3 SPAD units (SPAD value between 0 and 50) Reproducibility: Within ± 0. 5 SPAD units (SPAD value between 0 and 50) Temperature drift: Less than ± 0. 4 SPAD units/°C Temperature range: Operation: 0 to 50°C; Storage: - 20 to +55°C Dimensions: 164 ×78 × 49mm (6-7/16 × 3-1/16 × 1-15/16 in. ) Weight: 225g (7-15/16 oz. ) (not including batteries) Other: Warning buzzer; User calibration function Specification subject to change without notice ©2003 KONICA MINOLTA SENSING, INC. 9242-4817-41 AHIDPK 13 Printed in Japan [. . . ]