Comparison of Supplemental LED Top- and Interlighting for Year-Round Production of Cherry Tomato

Abstract

Supplemental lighting is common in northern countries or during winter greenhouse tomato production. We investigated the effect of supplemental lighting treatments on cherry tomato (‘Jun-Ama’) yield, productivity (light-use efficiency (LUE) and energy-use efficiency (EUE)), and fruit quality under high irradiance (average greenhouse daily light integral (DLI) = 14.5 mol m−2 d−1). Supplemental lighting treatments contained average DLIs of 2.7, 4.9, and 7.6 mol m−2 d−1 for interlighting, toplighting, and inter- + toplighting, respectively. Supplemental LED lighting increased fruit yield by 18, 41, and 40% with inter-, top-, and inter- + toplighting, respectively, compared with the control. Interlighting increased fruit number (+11%), and top- and inter- + toplighting also increased the fruit number (+26%, +27%) and weight (+10%, +10%), respectively. LUE and EUE were comparable between inter- and toplighting, while inter- + toplighting decreased LUE by 21 and 38%, and EUE by 38 and 31% compared with inter- and toplighting, respectively. All LED supplemental treatments significantly increased total soluble solids compared with the control. Total acidity and lycopene content were unchanged in all treatments. In conclusion, LED supplemental lighting with inter- or toplighting improved cherry tomato yield and quality, but inter- + toplighting was inefficient under high irradiation.