Articles
USE OF DISPOSABLE FILM SENSOR FOR ANALYZING UNIFORMITY OF DAILY LIGHT INTEGRAL INSIDE A GREENHOUSE
Article number
893_52
Pages
517 – 524
Language
English
Abstract
Designing greenhouse structure to create maximum and uniform light transmission is crucial in greenhouse crop production.
Historically, a mathematical approach to compute the light transmission in the greenhouse has been demonstrated as an effective way to understand the seasonal and spatial uniformity of light inside a greenhouse as affected by structural design, time of day, and geographical location.
Nevertheless, actual measurements of spatial light distribution inside the greenhouse are either costly or logistically challenging (with wiring numerous sensors to a recording device). As part of our applied instrumentation course offered by the University of Arizonas Controlled Environment Agriculture program, we evaluated an acetylcellulose film sensor containing dye that degrades under solar radiation, as a potential quick tool to analyze the light distribution inside the greenhouse.
A 480-m2 greenhouse with a saw-tooth roof was used in the preliminary study conducted in March 2005. During the experiments, OptLeaf O1-D sensor strips (Taisei E&L, Tokyo, Japan) were placed in 32 locations over a horizontal plane over the tomato plant canopy (2.6 m above ground), created by petri dishes hanging in the selected locations.
The absorbance of each strip was measured at a 492 nm wavelength using an ordinary laboratory spectrophotometer every day for four days, and was converted to integrated photosynthetic photon flux (PPF) using a predetermined calibration curve obtained in the same greenhouse by comparing with a QSO quantum sensor (Apogee Instruments, Logan, Utah, USA) connected to a CR-10X datalogger (Campbell Scientific, Logan, Utah, USA). The results showed that use of disposable film sensor was a useful tool to understand spatial distribution of daily PPF inside a greenhouse with a relatively simple set-up and small costs (~$ 1.00 per 1×3.5-cm sensor strip). However, the sensor also showed a limited accuracy and cautions are needed in measurements and interpretation of the measured values.
Historically, a mathematical approach to compute the light transmission in the greenhouse has been demonstrated as an effective way to understand the seasonal and spatial uniformity of light inside a greenhouse as affected by structural design, time of day, and geographical location.
Nevertheless, actual measurements of spatial light distribution inside the greenhouse are either costly or logistically challenging (with wiring numerous sensors to a recording device). As part of our applied instrumentation course offered by the University of Arizonas Controlled Environment Agriculture program, we evaluated an acetylcellulose film sensor containing dye that degrades under solar radiation, as a potential quick tool to analyze the light distribution inside the greenhouse.
A 480-m2 greenhouse with a saw-tooth roof was used in the preliminary study conducted in March 2005. During the experiments, OptLeaf O1-D sensor strips (Taisei E&L, Tokyo, Japan) were placed in 32 locations over a horizontal plane over the tomato plant canopy (2.6 m above ground), created by petri dishes hanging in the selected locations.
The absorbance of each strip was measured at a 492 nm wavelength using an ordinary laboratory spectrophotometer every day for four days, and was converted to integrated photosynthetic photon flux (PPF) using a predetermined calibration curve obtained in the same greenhouse by comparing with a QSO quantum sensor (Apogee Instruments, Logan, Utah, USA) connected to a CR-10X datalogger (Campbell Scientific, Logan, Utah, USA). The results showed that use of disposable film sensor was a useful tool to understand spatial distribution of daily PPF inside a greenhouse with a relatively simple set-up and small costs (~$ 1.00 per 1×3.5-cm sensor strip). However, the sensor also showed a limited accuracy and cautions are needed in measurements and interpretation of the measured values.
Authors
E. Fitz-Rodríguez, J. Nelkin, C. Kubota
Keywords
controlled environment, light transmission, photosynthetic photon flux
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