In order to establish fully automated pest control in a greenhouse, the authors developed a spraying vehicle that travels along furrows. Since a power sprayer mounted on the vehicle is driven by a gasoline engine, plants in the greenhouse might be injured by exhaust gas. Gasoline exhaust contains ethylene. Ethylene is one of the plant hormone that makes plants shed their flowers and buds. The objectives of this study are to clarify the effects of ethylene contained in the gasoline exhaust on the shedding of flowers and buds of plants grown in greenhouse, and to determine a countermeasure against shedding.
1. In a closed vinyl house, the engine was operated for 5 (high ethylene concentration) and 2.5 (low concentration) minutes. Potted sesame and sweet pepper plants were exposed to the exhaust gas for 2, 4 and 12 hours. The longer the fumigation time the more flowers and buds were shed. However, flowers and buds increased when plants were fumigated for 2 hours in either concentration.
2. In a closed or partially opened vinyl house, the engine was operated for 5 minutes and potted sesame plants were exposed to the exhaust gas for 12 hours. In the closed vinyl house, ethylene concentration was 0.75ppm even 12 hours after the engine was stopped, and flowers and buds were shed markedly. In contrast, in the partially opened vinyl house, ethylene concentration decreased to 0ppm 3 hours after the engine was stopped, and neither flowers nor buds were shed.
As mentioned above, it was revealed that shedding of flowers and buds caused by ethylene contained in the gasoline exhaust could be prevented by providing suitable ventilation.
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