2017 ASHS Annual Conference

Carbon dioxide (CO₂) plays an important role in plant photosynthesis and sometimes low level of CO₂ could be a limiting factor in the greenhouse crop production. To understand the effect of elevated CO₂ in leafy green production under hydroponics system, a greenhouse study was conducted. Two identical greenhouses were used and CO₂ was supplemented to maintain 1000 ppm in one of the greenhouses from 7 a.m. to 1:00 p.m. Nutrient film technique (NFT) was installed in each of the greenhouses and lettuce (Lactuca sativa L. ‘Auvona’), basil (Ocimum basilicum L. ‘Cardinal’), and Swiss chard (Beta vulgaris L. ‘Magenta Sunset’) were grown at 250 ppm nitrogen level. Each plant species had three replications and each replication of lettuce and basil had 18 plant samples and Swiss chard had 15 samples. Throughout the study the pH level was maintained at 5.5-6.5. Height, width, fresh weight, leaf area, specific leaf area, atLEAF and SPAD value were recorded at 40 days after transplanting and dry weight was recorded after harvesting. Nutrient analysis of plant tissue was carried out to find out the percent nutrient contents in plant tissue. The results showed greater dry weight and fresh weight in all species under elevated CO₂ condition. Similarly, plants grown under elevated CO₂ had greater leaf area and root dry weight compared to ambient condition.