Effects of the spacing of roof ventilation devices on the environment and the yield of oriental melons in single-span plastic greenhouses

Abstract

The purpose of this study is to provide the standard for the proper installation of roof ventilation devices in single-span plastic greenhouses. The amount of ventilation was 19,140 m3 h-1 in the greenhouse with fans installed at intervals of 15 m, and 15,845 m3 h-1 with fans installed at intervals of 20 m. The amount of ventilation was 14,961 m3 h-1 in the greenhouse with stacks installed at intervals of 6 m, and 13,414 m3 h-1 with stacks installed at intervals of 8 m. As a result of analyzing changes in average day-time temperature during June, a high-temperature period, it was found that the narrower the spacing of ventilation devices, the lower the air temperature; and that air temperature in the greenhouse with fans was lower than that in the greenhouse with stacks. As a result of examining the yield of oriental melons per the span of greenhouse (605 m2), it was found that the yield in the greenhouse with fans installed at intervals of 15 m was 5,075 kg, 8.6% more than that in the greenhouse with fans installed at intervals of 20 m. And the yield in the greenhouse with stacks installed at intervals of 6 m was 4,405 kg, 7.2% more than that in the greenhouse with stacks installed at intervals of 8 m. As a result of analyzing economic efficiency according to roof ventilation device treatments, taking into account the value of oriental melon production, the depreciation of ventilation devices, the electric charges, and the expenses for selection and packaging, it was found that income increased KRW 865,450 in the case of spacing fans 15 m apart, compared with the case of spacing them 20 m apart; and that income increased KRW 660,690 in the case of spacing stacks 6 m apart, compared with the case of spacing them 8 m apart.