Analysis of Spatial and Vertical Variability of Environmental Parameters in a Greenhouse and Comparison of Carbon Dioxide Concentration in Two Different Types of Greenhouses

Abstract

This study was aimed to investigate spatial and vertical characteristics of greenhouse environments according to the location of the environmental sensors, and to investigate the correlations between temperature, light intensity, and carbon dioxide (CO 2 ) concentration according to the type of greenhouse. Temperature, relative humidity (RH), CO 2 , and light sensors were installed in the four-different vertical positions of the whole canopy as well as ground and roof space at the five spatial locations of the Venlo greenhouse. Also, correlations between temperature, light intensity, and CO 2 concentration in Venlo and semi-closed greenhouses were analyzed using the Curve Expert Professional program. The deviations among the spatial locations were larger in the CO 2 concentration than other environmental factors in the Venlo greenhouse. The average CO 2 concentration ranged from 465 to 761 µmol•mol -1 with the highest value (646 µmol•mol -1 ) at the Middle End (4ME) close to the main pipe (50∅) of the liquefied CO 2 gas supply and lowest (436 µmol•mol -1 ) at the Left Middle (5LM). The deviation among the vertical positions was greater in temperature and relative humidity than other environments. The time zone with the largest deviation in average temperature was 2 p.m. with the highest temperature (26.51°C) at the Upper Air (UA) and the lowest temperature (25.62°C) at the Lower Canopy (LC). The time zone with the largest deviation in average RH was 1 p.m. with the highest RH (76.90%) at the LC and the lowest RH (71.74%) at the UA. The highest average CO 2 concentration at each hour was Roof Air (RF) and Ground (GD). The coefficient of correlations between temperature, light intensity, and CO 2 concentration were 0.07 for semi-closed greenhouse and 0.66 for Venlo greenhouse. All the results indicate that while the CO 2 concentration in the greenhouse needs to be analyzed in the spatial locations, temperature and humidity needs to be analyzed in the vertical positions of canopy. The target CO 2 fertilization concentration for the semi-closed greenhouse with low ventilation rate should be different from that of general greenhouses.

Model-based Calculations of Ventilation Rate, Carbon Dioxide (CO2) Absorption Rate by Plants, and Amounts of Ventilated and Supplied CO2 for Tomato Hydroponic Greenhouse during a Winter Season

“…작물의 광합성 능력은 온실 내 온도, 광, 근권수분이 적정 수준으로 충족된 조건에서 CO 2 농도가 증가하였을 때 촉진되지만 공급량에 비례적 이지 않으며 (Esmeijer, 1999), 온실의 환기율에 의해 최적 CO 2 농도 설정점은 달라질 수 있다고 하였다 (Sanchez-Guerrero et al, 2005;Kläring et al, 2007). 본 연구팀의 선행연구에서 반밀폐형 온실의 CO 2 시용 효율은 공조실을 통한 환기로 인해 CO 2 가 외부로 유출되지 않으면서 재사용되므로 일반 온실에 비해 효율이 높다는 것을 확인할 수 있었다 (Jeong et al, 2022). 하지 만 일반 벤로온실에서는 광도와 온도에 따라 환기를 조절하므로 이에 대한 능동적인 CO 2 공급량 조절이 필요할 것으로 판단하 였다.…”