Effects of supplemental lighting and cover materials on growth, photosynthesis, biomass partitioning, early yield and quality of greenhouse cucumber

Seedless cucumber (Cucumis sativus L.) cv. Flamingo was grown in winter time in glass, double-inflated polyethylene (D-poly) and twin-wall acrylic (acrylic) greenhouses with or without 16h (3:00-19:00 hours) of supplemental lighting to investigate the effects of the cover materials and supplemental lighting on plant growth, photosynthesis, biomass partitioning, early fruit yield and quality. Supplemental lighting promoted plant development and increased leaf chlorophyll, leaf photosynthesis, plant biomass and early marketable yield production. Supplemental lighting also increased biomass allocation to fruit, fruit dry matter content and skin chlorophyll content. There was little difference in leaf photosynthesis rates of plants under the three cover materials although solar irradiance on sunny days was much higher in glass than in D-poly houses. Dry matter production of plants grown in glass houses was higher than in D-poly and acrylic houses, but dry matter partitioning was not different under the three greenhouse covers. The high dry matter production in glass houses was translated into high fruit dry matter content, but not high early marketable yield. Cucumber early marketable yield in glass houses was similar to that in D-poly but lower than in acrylic houses. The supplemental lighting sufficiently compensated for the loss of solar radiation in D-poly and acrylic houses. (C) 1999 Elsevier Science B.V. All rights reserved.