ISHS Acta Horticulturae 807: International Symposium on Strategies Towards Sustainability of Protected Cultivation in Mild Winter Climate
INSECT SCREENS FOR INTEGRATED PLANT PROTECTION IN GREENHOUSES |
| Authors: | U.N. Mutwiwa, H.J. Tantau |
| Keywords: | greenhouse microclimate, insect-proof screens, natural ventilation, UV-absorption |
| Abstract:
Covering ventilation openings and sidewalls of a greenhouse with insect-proof screens has the advantage of reducing the entry of insect pests into the greenhouse, but at the same time, affects the microclimate. The effect of two insect-proof screens on the microclimate and plant growth was investigated in two naturally ventilated greenhouses. The insect-proof screens were expected to protect the plants either by their optical (UV-blocking) or physical (mesh-size) properties. Tomato Solanum lycopersicum (cv FMTT 260) was used as a model crop during the cool season in central Thailand. Measurements from wind tunnel experiments revealed that the insect screen with a finer mesh size, Econet-T, offered more resistance to air flow. In addition, both pressure drop and discharge coefficient (Cd) for all nets evaluated increased with velocity. For the nets selected to cover the greenhouses, the Cd for Econet-T ranged from 0.19 at a velocity of 0.41 m s-1 to a maximum of 0.26 at the highest velocity (1.09 m s-1). Corresponding values for the insect-proof screen with bigger mesh size, Bionet, were 0.40 and 0.32 calculated at the lowest (0.51 m s-1) and highest (0.96 m s-1) velocities respectively. The effects of the insect-proof nets on microclimate and plant growth are discussed. | |
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