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In this study, the shading over and under roof (T1), fog and fan (T2), water streaming over roof (T3), water sprinkling over roof (T4), and water sprinkling with white shading net over roof (T5) were compared to make clear the dropping effect of temperature for summer culture of flower crops in the experimental plastic house. The temperature in the experimental plastic house of all treatments was dropped 2.0∼6.5℃ more under ventilated condition than closed one. The lowest temperature showed in T1 under ventilated condition and T2 under closed condition, respectively. The maximum temperature at 13:00 were high in T1 and T5 during June and July, and in the all treatments except T2 during August and September. Transmitted light intensity to shading treatments was highest in T3, followed by T4, T2, and T1. Transmitted light intensity in T2 and T4 by operating temperature dropping methods was showed a biggest decrease of 15∼18%, compared to non-operating ones. In the net photosynthetic rates due to the dropping effect of temperature and transmitted light intensity, Rosa hybrida was highest in T2 in low shading rates, and was lowest in T1 and T5 in high shading rates. It was highest in T2 of Lilium elegans, T4 of Phalaenopsis schilleriana, and T1 of Coleus blueni, respectively. There were no significance between all treatments of Cymbidium hybrida on it. The shading plants could be practically good by shading methods as in T1 and T5 with low light transmission, because Epipremnum aureum as shading plant was high in T1, T4, and T5 on it. Whereas sun plants as Rosa hybrids could be good in T2 and T3 to drop the temperature and maintain the high light transmission. Net photosynthetic rates due to the dropping effect of temperature and light transmission were affected by growth habit, light intensity, and optimum temperature of crop growth. Therefore, these results indicated that the availability of shading net and roof sprinkling were an effective method to decrease the high temperature during summer time.
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