Apogee S2-131-SS Manual do Proprietário - Página 4

Procurar online ou descarregar pdf Manual do Proprietário para Acessórios Apogee S2-131-SS. Apogee S2-131-SS 15 páginas. Red - far-red sensors

INTRODUCTION

Specific wavelengths of radiation trigger distinct responses in plants. Red and far-red wavelengths are of particular

interest because they influence photosynthetic and morphogenic activity. Phytochrome pigments in plants are

sensitive to varying ratios of red and far-red radiation, providing information to the plant about the light

environment, and therefore, optimal growth patterns. Increasing the fraction of red radiation indicates less

shading and generally results in more conservative vertical growth patterns, while increasing the far-red radiation

fraction indicates more shading and results in more aggressive vertical growth patterns.

Red - far-red sensors are designed to have spectral sensitivities that approximate the phytochrome absorption

spectrum. Red - far-red sensors quantify properties of radiation sources, not plant responses. However, inferences

of plant responses can be made from measurements of the lighting/shading environment, so it is important that

red - far-red sensors have high sensitivity in the wavelength ranges where plants are most sensitive (i.e., the

wavelength ranges that drive the strongest responses in plants), hence red - far-red sensor spectral responses

should approximate the phytochrome absorption spectrum.

The primary application of red - far-red sensors is monitoring plant light environments, including calculation of the

red to far-red ratio (red photon flux density / far-red photon flux density) and far-red fraction (far-red photon flux

density / sum of red and far-red photon flux densities), in photobiology studies (e.g., researching plant

morphogenic activities).

Apogee Instruments model S2-131 red - far-red sensors consist of a cast acrylic diffuser, pair of photodiodes that

measure specific wavelength ranges (red peak near the red peak of phytochrome absorption and far-red peak near

the far-red peak of phytochrome absorption), and signal processing circuitry mounted in an anodized aluminum

housing, and a cable to connect the radiometer to a measurement device. Sensors are designed for continuous

measurement in indoor and outdoor environments. Model S2-131 sensors output two voltages, one from each

photodetector, that are directly proportional to the radiation incident on a planar surface (does not have to be

horizontal), where the radiation emanates from all angles of a hemisphere.