Interrupted dark phase does not affect greenhouse tomato growth and yield

Abstract

Abstract The increased generation of electrical energy from renewable sources leads to variations in production accompanied by high price volatility. The use of surplus capacities for the artificial illumination of greenhouse crops would increase yield while enabling electricity to be purchased at low prices. This, however, requires the frequent turning on and off of lamps, and may affect circadian rhythm. A daily dark phase of six hours is recommended for the tomato. Can this phase be split? To determine this, a greenhouse experiment was conducted with artificial light added continuously or intermittently to adult tomato plants at night while guaranteeing a daily total dark phase of seven hours. Interrupting the dark phase did not affect tomato growth or yield, even though the light-induced circadian clock must have been significantly affected. However, due to the thermal energy supplied by lamps, the air temperature in the greenhouse was significantly higher during light phases than dark phases, which may precondition the plant tolerance to the subdivided night. The findings suggest it would be worthwhile conducing further research into the use of volatile energy for greenhouse crop production.