User manual KONICA SD-P BROCHURE

[. . . ] 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. [. . . ] Quick, easy measurements Measurements are taken by simply inserting a leaf and closing the measuring head. It is not necessary to cut the leaf, so the same leaf can be measured throughout the growing process. Water-resistant The SD-P is water-resistant, so it can be used outside even in the rain. Low power consumption The SD-P uses LED light sources, resulting in extremely low power consumption. To take advantage of this characteristic of chlorophyll, the SD-P measures the absorbances of the leaf in the red and near-infrared regions. Using these two transmittances, the meter calculates a numerical SPAD value which is proportional to the amount of chlorophyll present in the leaf. A Trancemittance B 400 500 600 700(nm) Ultraviolet Wavelength Infrared Applications 3. 5 Leaf-blade nitrogen concentration 3. 1 2. 9 2. 7 2. 5 2. 3 2. 1 1. 9 1. 7 24 26 28 30 32 34 Measured SPAD value 3. 3 y =0. 079 x - 0. 154 r =0. 908*** n =68 Sasanishiki rice plant development 40 35 Ear differentlation period 30 Young ear formation period Ear fertility (16 -18cm) Bursting period (8cm) Fully formed ears appear 25 Days before fully formed ears appear 9. 1 Date(month. day) 7. 1 (3mm) Young ear growth line (1mm) 10. 3 10. 8 30 7. 10 25 20 7. 20 1984 1985 36 38 40 42 9. 5 35 12. 5 13. 0 15 10 7. 30 5 0 8. 14 Measured SPAD value Checking the nutritional condition of plants The chlorophyll present in the plant leaves is closely related to the nutritional condition of the plant. As can be seen from the graph below, the chlorophyll content (represented by the measured SPAD value) will increase in proportion to the amount of nitrogen (an important plant nutrient) present in the leaf. For a particular plant species, a higher SPAD value indicates a healthier plant. Determining when additional fertilizer is necessary A decrease in the SPAD value indicates a decrease in the chlorophyll content and nitrogen concentration. [. . . ] 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. [. . . ]