Diurnal and Night Change in Greenhouse's Microclimatic Condition

Abstract

In modern greenhouses, measurements of climate conditions are required to give the grower a better understanding on how each factor affect growth and how to achieve maximal crop productiveness. The measurements and resultant optimal conditional adjustments enable the grower to improve productivity and achieve maximum costs and energy savings. Data of climate parameters were collected and analyzed to determine night and diurnal change of solar radiation, air temperature and humidity inside greenhouse, temperature and humidity difference between inside and outside air of a greenhouse, the temperature difference between the soil and the inside air and the transparency behaviour of the covering material. Results shows that diurnal solar radiation is higher outside than inside of greenhouses as expected. The maximum solar radiations were about 742 W/m²and 545 W/m² for both outside and inside of the structure respectively towards noon. However, the ratio of solar radiation inside to solar radiation outside the greenhouse ratio was quite constant throughout the daytime at values of 0.8 – 0.7. There was lower temperature inside the greenhouse during the night or at the sunset while in the daytime the inside temperature was higher with a steady increase in the difference between the two up to noon time. Also, there was clear difference between inside relative humidity and outside relative humidity in the night and day up to 11:00 AM. Opening the screens for ventilation was used to control or regulate the microclimate condition of the greenhouse. Soil temperature was higher/lower than air temperature during night/day indicating on the possibility to use the soil as a heat buffer.

Keywords: Greenhouses, relative humidity, temperature, solar radiation

Nigerian Journal of Technological Research, 8(2), 2013