Carbon Dioxide Enrichment of High-value Crops under Tunnel Culture

Abstract

The feasibility of field-scale CO 2 enrichment of vegetable crops grown under tunnel culture was studied with cucumber (Cucumis saivus L. cv . Dasher II), summer squash (Cucurbita pepo L. cv . Gold Bar), and tomato (Lycopersicon escukntum Mill. cv . Bingo) grown under polyethylene tunnels. The drip irrigation system was used to uniformly deliver a CO 2 -enriched air stream independent of irrigation. Carbon dioxide was maintained between 700 and 1000 μl·liter -1 during daylight hours. Enrichment began immediately after crop establishment and continued for ≈4 weeks. At the end of the treatment phase, enrichment had significantly increased plant dry weight in the 2 years of tests. This growth advantage continued through harvest, with enriched cucumber, squash, and tomato plots yielding 30%, 20%, and 32% more fruit, respectively, in 1989. In 1990, cucumber and squash yields were increased 20%, and 16%, respectively. As performed, the expense of CO 2 enrichment represented less than a 10% increase in total preharvest costs. A similar test was conducted on fall-planted strawberries (Fragaria × ananassa Duch. cvs . Irvine and Chandler). Carbon dioxide enrichment under tunnel culture modestly increased `Irvine' yields but did not affect `Chandler'.