Influence of CO2 Enrichment in Greenhouses on Pepper Plant (Capsicum annuum L.) Yield under High Temperature Conditions

The CO2 enrichment of greenhouses is a method to increase plant growth and productivity and it is applied successfully in many regions all over the world. However, in places where high temperatures occur during the main cultivation period, special application of the CO2 enrichment is needed due to the fact of high ventilation needs which reduce the available time for CO2 application leading to a lower crop yield. This work examines the effect of artificial CO2 application on the optimum increase of pepper plants productivity under high temperature conditions. This study was performed in two identical greenhouses (experimental and control greenhouse) and was repeated three times, twice in the spring cultivation period and once in the autumn. During this study, a characteristic property of plant physiology was exploited. It is known that increasing the CO2 concentration at levels higher than normal the optimum temperature of the C-3 plants growth is also increased. This results in a reduction of time needed for ventilation of greenhouses allowing the application of CO2 for longer period. The results showed that the CO2 enrichment technique used under high temperatures confers beneficial outcomes, like all the other known enrichment techniques. In the experimental greenhouse, where the enrichment was applied, plants were absorbing CO2 at high rates and showed an improved growth and production of about 27% compared to those in the control greenhouse regardless of higher than optimum temperature levels in the experimental greenhouse.