Plant growth in greenhouses using CO2 enrichment at high temperatures with a passive solar system

D. Vafiadis, A. Martzopoulou, A. Denizopoulou, V.P. Fragos
Most cultivated plants in greenhouses are C3 plants. Experiments have shown that by the enrichment of CO2, at threefold levels rather than the normal (410 ppm), the optimum growth temperature of these plants is shifted higher by 5-10°C, reaching 30-32°C. This allows to delay the ventilation starting time, and hence enables to increase both the hours during the day with enrichment application of CO2 feasible and the number of days throughout the year. During the spring and autumn months, three experiments were conducted in two greenhouses at the farm of the Aristotle University of Thessaloniki, one of which was used as a control plot. CO2 enrichment took place under high temperatures and controlled ventilation. In two of the experiments, a passive solar system consisting of water sleeves was also used. The selected crops are tomatoes, cucumbers and peppers. A total of 900 plants were used, 300 in each experiment. The cultivation of tomatoes showed faster growth. The average height of the plants was 8.64% higher and the central stem circumference was wider by 7.76%. The cultivation of cucumbers showed accelerated growth with precocity and increase in production. The plants were on average 10.05% higher in the second experiment and 8.16% in the third. Additionally, there was a shortening of the harvest time by 4-10 days. The produced fruit quantity was by 16.54 and 12.9%, respectively, greater in the two experiments. The cultivation of peppers showed higher productivity in all three experiments. The difference in fruit yields was 14.1, 17.5 and 12.32% in all three experiments. The results also pinpointed that CO2 enrichment at high temperatures resulted in energy saving due to reduced ventilation needs. Research has also shown that relative humidity is not a restricting factor.
Vafiadis, D., Martzopoulou, A., Denizopoulou, A. and Fragos, V.P. (2020). Plant growth in greenhouses using CO2 enrichment at high temperatures with a passive solar system. Acta Hortic. 1296, 417-424
DOI: 10.17660/ActaHortic.2020.1296.54
CO2 enrichment, high temperatures, passive solar system, plant growth, greenhouse

Acta Horticulturae