EFFECTS OF GAS EXHAUSTED FROM GASOLINE ENGINE ON PLANTS GROWN IN THE GREENHOUSE

In order to establish a fully automatized pest control in the a greenhouse , the authors developed a prototype of microcomputer installed spraying vehicle which traveled along the furrows. Since a power sprayer mounted on the vehicle was driven by gasoline engine, plants grown in the greenhouse might be injured by the gas exhausted from the engine. Thus , effects of exhausted gas on photosynthetic rate and the shedding of flowers and buds of plants were examined. At first, effects of exhausted gas on photosynthetic rate of potted sweet pepper (Capsicum annuum L.) and eggplant(Solanum melongena L.) plants were examined. In a closed vinyl house the engine was operated for 5 minutes and plants were exposed to the gas for 2hours in the daytime on a fine day. Photosynthetic rate did not significantly decreased by the treatment in both species. Secondly, effects of ehtylene on the shedding of flowers and buds of sesame (Sesamum indicum L. ) were examined. In the closed and partiall opened vinyl house, the engine was operated for 5 minutes and potted sesame plants were exposed to the gas for 12 hours in the night. In partially opened vinyl house, ethylene concentration decreased to 0 ppm 3 hours after the engine was stopped and flower and bud did not shed. In contrast, when vinyl house was closed ethylene concentration was 0.75 pm even 12 hours after the engine was stopped and flowers and buds shed markedly and epinasty was observed in upper young leaves. As mentioned above , it was revealed that injury of plants in the greenhouse caused by the gas exhausted from a gasoline engine could be prevented by providing suitable ventilation.