S06 - Session O2 - Estimation of supplemental light requirements of greenhouse crops based on canopy light interception using 3D plant models and ray-tracing simulation.
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Authors: Inha Hwang *, Dongpil Kim, Seungri Yoon, Jin Hyun Kim, Jung Eek Son
Recently, crops are grown in high roof, densely planted greenhouses to increase yields, but as a result, there is a lack of light in the crop canopy. For supplemental lighting, the concept of daily light integral (DLI) is popular, but it is not easy to use with inter-canopy lighting schemes. Ray tracing simulation with 3D plant models can be an appropriate solution for calculating the light intercepted by actual leaf surfaces. The objective of this study is to estimate supplemental lighting requirement of crops based on canopy light interception using 3D plant model and ray-tracing simulation. Three dimensional-scanned models of sweet pepper and tomato grown at a planting density of 3.5 plants m -2 were constructed at three different growth stages (30, 90, and 140 days after transplanting). In the simulation, HPS lamps were arranged at above the crop canopy and LED lamps were located at the middle of the canopy. The spatial light distribution on the crop surface was calculated through ray-tracing simulation. To reflect the external light environment according to growth stage, the light intensities at each growth stage were set to September, November, and January, respectively. The accumulated light at the top of the plant canopy and the accumulated light interception on the surface of the canopy showed a linear relationship. Using this equation, the accumulated light interception of sweet pepper and tomato plants according to growth stage could be converted to the corresponding DLI values, from which supplemental light requirements could be calculated. This method can be useful for estimating supplemental lighting requirement based on accurate light interception and applying it to greenhouses. (This work was supported by IPET and KosFarm funded by MAFRA, MSIT, and RDA; 421001-03)