Continuous LED Lighting Can Significantly Reduce Light Fixture Costs without Compromising Fruit Yield and Quality in Greenhouse Cucumber Production.
Citation
Hao, X., Lanoue, J. and Zheng, J. 2020. Continuous LED Lighting Can Significantly Reduce Light Fixture Costs without Compromising Fruit Yield and Quality in Greenhouse Cucumber Production. HortScience 55(9): S363 (Abstract).
Plain language summary
Supplemental lighting is essential for year round greenhouse crop production in regions with
low natural light conditions. The improvement in plant growth and yield by supplemental lighting is
largely dictated by the total amount of light provided during a day (daily light integral (DLI) – intensity ×
photoperiod). It is more economical to achieve desired DLIs with long photoperiod of supplemental
light at low light intensity because it uses less light fixtures, reducing initial capital costs. A 24h (continuous lighting) can reduce light fixture cost by 1/3 in comparison to the conventional 16-17h of lighting used in commercial greenhouse vegetable production. The conventional 16-17h of lighting photoperiod was used in greenhouse fruit vegetable (such as tomatoes and cucumbers) production because longer (>17h) lighting leads to photo-injury (characterized by leaf chlorosis and decrease in photosynthesis) and no further yield gain, based on researches conducted using conventional lighting sources such as high pressure sodium (HPS) light. There have been very little research on the photoperiod response of greenhouse fruit vegetables to energy-efficient LED lighting. In a previous study, we have found that alternating red and blue LED lighting can eliminate photo-injury and improve early fruit yield in tomato production. Therefore, we investigated the response of greenhouse mini-cucumbers to CL with red and blue LED light in this study. The study was conducted in a greenhouse with 200 m2 of growing area during winter 2019-20. The greenhouse was divided into 16 sections using white curtains. Four lighting strategies were applied to the 16 plots in a Latin-Square design with 4 replications: (1) 16h red and blue together and 8 h darkness (control), (2) 24h red and blue together, (3) 16h red followed by 8h of blue, and (4) 12h of red followed by 12h of blue LED light. The four lighting strategies had the same daily light integral (12.1 mol m-2 d-1) and red to blue supplemental light ratio (86% to 14%). There was little difference in plant growth, photosynthesis and fruit yield among the 4 lighting treatments over the 4 months of fruit production (a full crop cycle). Therefore, the CL lighting strategy with red and blue LED light or alternating red and blue LED light can be used in min-cucumber production to reduce light intensity and light fixture costs.
Abstract
Supplemental lighting is essential for year round greenhouse crop production in regions with
low natural light conditions. The improvement in plant growth and yield by supplemental lighting is
largely dictated by the total amount of light provided during a day (daily light integral (DLI) – intensity ×
photoperiod). It is more economical to achieve desired DLIs with long photoperiod of supplemental
light at low light intensity because it uses less light fixtures, reducing initial capital costs. A 24h (continuous lighting) can reduce light fixture cost by 1/3 in comparison to the conventional 16-17h of lighting used in commercial greenhouse vegetable production. The conventional 16-17h of lighting photoperiod was used in greenhouse fruit vegetable (such as tomatoes and cucumbers) production because longer (>17h) lighting leads to photo-injury (characterized by leaf chlorosis and decrease in photosynthesis) and no further yield gain, based on researches conducted using conventional lighting sources such as high pressure sodium (HPS) light. There have been very little research on the photoperiod response of greenhouse fruit vegetables to energy-efficient LED lighting. In a previous study, we have found that alternating red and blue LED lighting can eliminate photo-injury and improve early fruit yield in tomato production. Therefore, we investigated the response of greenhouse mini-cucumbers to CL with red and blue LED light in this study. The study was conducted in a greenhouse with 200 m2 of growing area during winter 2019-20. The greenhouse was divided into 16 sections using white curtains. Four lighting strategies were applied to the 16 plots in a Latin-Square design with 4 replications: (1) 16h red and blue together and 8 h darkness (control), (2) 24h red and blue together, (3) 16h red followed by 8h of blue, and (4) 12h of red followed by 12h of blue LED light. The four lighting strategies had the same daily light integral (12.1 mol m-2 d-1) and red to blue supplemental light ratio (86% to 14%). There was little difference in plant growth, photosynthesis and fruit yield among the 4 lighting treatments over the 4 months of fruit production (a full crop cycle). Therefore, the CL lighting strategy with red and blue LED light or alternating red and blue LED light can be used in min-cucumber production to reduce light intensity and light fixture costs.