Abstract
The responses of cucumber on forced culture involving a range of carbon dioxide concentrations and length of supplementation times in a greenhouse, a long-term supplementation from 7:30 a.m. to 14:30 p.m. at 500 ppm, and a short-term supplementation from 7:30 a.m. to 10:30 a.m. at 1,000 ppm, were examined together with those on non-enriched treatment. Both carbon dioxide enrichments increased the marketable fruit yield by 39–55%. Even if expenditure due to carbon dioxide enrichment is subtracted, the gross return was 58,000–96,000 yen per 100 m2 higher than non-enriched culture. In the long-term supplementation the growth yield was larger, and the amount of carbon dioxide used was less than in the short-term supplementation. Long-term supplementation at 500 ppm was cost-effective.
