Specific wavelengths of radiation elicit distinct plant responses. Radiation that drives photosynthesis is called photosynthetically active radiation (PAR) and is typically defined as total radiation across a range of 400 to 700 nm. PAR is often expressed as photosynthetic photon flux density (PPFD): photon flux in units of micromoles per square meter per second (µmol m-2s-1, equal to microEinsteins per square meter per second) summed from 400 to 700 nm (total number of photons from 400 to 700 nm).
In addition to PPFD, red and far-red wavelengths are of particular interest because they influence photosynthetic and morphogenic activity. Phytochrome pigments sensitive to varying ratios of red and far-red light provide information to the plant about its light environment and, therefore, its optimal growth patterns. Increasing the fraction of red light indicates less shading and generally results in more conservative vertical growth patterns; increasing the far-red fraction indicates more shading and results in more aggressive vertical growth patterns. Sensors that measure PAR and red/far-red radiation are often called PAR-FAR sensors. These sensors quantify both PPFD and far-red radiation incident on the sensor’s detecting surface.
bob体育竞技APOGEE仪器S2系列PAR-FAR传感器由铸造丙烯酸漫射器组成,测量特定波长范围的一对光电探测器,信号处理电路安装在阳极氧化铝壳体中,以及连接到辐射计测量装置的电缆。传感器是盆栽固体,没有内部空间,设计用于室内和室外环境的连续测量。S2传感器输出每个光电探测器的模拟电压,该模拟电压与入射在平面表面上的红色/远红色辐射(不必是水平)的红色/远红色辐射成正比,其中辐射从半球的所有角度散发出来。
S2-141-SS* | S2-441-SS | S2-442-SS. | |
---|---|---|---|
电源 | 自我支持 | 5.5至24 V DC | 5.5至24 V DC |
电流消耗 | - | 1.4 mA(静止),1.8 mA(活跃) | RS-232 37 mA; RS-485 quiescent 37 mA, active 42 mA |
Output (Sensitivity) | 每μmolm 0.01 mV-2s-1(par) 每μmolm0.02 mv-2s-1(Far-red) |
- | - |
Calibration Factor (reciprocal of sensitivity) | 100 µmol m-2s-1per mv(par) 50 µmol m-2s-1per mv (Far-red) |
Custom for each sensor and stored in firmware | Custom for each sensor and stored in firmware |
Calibration Uncertainty | ± 5 % | ± 5 % | ± 5 % |
Output Range | 0至40 mV(par) 0到20 mV(远红) |
SDI-12 | modbus. |
Measurement Repeatability | Less than 1 % | Less than 1 % | Less than 1 % |
Long-term Drift | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year |
Non-linearity | Less than 1 % (up to 4000 µmol m-2s-1) (PAR) Less than 1 % (up to 1000 µmol m-2s-1) (Far-red) |
Less than 1 % (up to 4000 µmol m-2s-1) (PAR) Less than 1 % (up to 1000 µmol m-2s-1) (Far-red) |
Less than 1 % (up to 4000 µmol m-2s-1) (PAR) Less than 1 % (up to 1000 µmol m-2s-1) (Far-red) |
响应时间 | Less than 1 ms | Less than 0.6 s | - |
视野 | 180° | 180° | 180° |
Spectral Ranges | 389至692 nm±5 nm(par) 702 to 761 nm ± 5 nm (Far-red) |
389至692 nm±5 nm(par) 702 to 761 nm ± 5 nm (Far-red) |
389至692 nm±5 nm(par) 702 to 761 nm ± 5 nm (Far-red) |
定向(余弦)响应 | ± 2 % at 45°; ± 5 % at 75° | ± 2 % at 45°; ± 5 % at 75° | ± 2 % at 45°; ± 5 % at 75° |
Temperature Response | Less than 0.1 % per C | Less than 0.1 % per C | Less than 0.1 % per C |
住房 | 阳极氧化铝机身用丙烯酸漫射器 | 阳极氧化铝机身用丙烯酸漫射器 | 阳极氧化铝机身用丙烯酸漫射器 |
IP Rating | IP68 | IP68 | IP68 |
Operating Environment | -40到70 c;0至100%相对湿度 | -40到70 c;0至100%相对湿度 | -40到70 c;0至100%相对湿度 |
Dimensions | 30.5 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height | 30.5 mm diameter, 37 mm height |
电缆的质量(5米) | 140克 | 140克 | 140克 |
电缆 | 5 m of shielded, twisted-pair wire with TPR jacket and stainless steel connector | 5 m of shielded, twisted-pair wire with TPR jacket and stainless steel connector | 5 m of shielded, twisted-pair wire with TPR jacket and stainless steel connector |
*The Output, Calibration Factor, and Output Range are variable from sensor to sensor, and the specifications listed are typical values.
Predicting Stem Elongation and Leaf Expansion: Percent far-red is a better predictor than PPE
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远红:被遗忘的光子
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Turning Photons Into Food
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