ABSTRACT
Installing reflective materials inside a greenhouse, especially a lean-to greenhouse, is one of the most effective and economical solutions to improve light intensity. Previous research reported that hanging reflective screen under the ridge of lean-to greenhouses has more light enhancement than that on the back wall. But the technical challenge in adopting this measure is to determine the optimal installation position of the reflective board with a width of about 1 m, the popular size of commercial products. If the position is too low, it is very inconvenient for operational and management activities. Tall plants may also block some of the light from reaching the reflective surface. On the other hand, if the board is installed too high, its light enhancing effect will be reduced (unpublished data). As to the angle between the reflective board and ground level, some researchers reported that it should be in the range of 75-85°. In fact, the optimal height and angle of reflective board should change with the time and location of the specific greenhouse. In this study, mathematical equations were developed and tested to enhance light intensity by optimizing the parameters of height and angle of reflective board inside lean-to greenhouses in various time and locations.
