Potential Use of a 24-Hour Photoperiod (Continuous Light) with Alternating Air Temperature for Production of Tomato Plug Transplants in a Closed System

Abstract

<jats:p>To evaluate the potential use of a 24-hour photoperiod for transplant production in a closed system, tomato (<jats:italic>Lycopersicon esculentum</jats:italic> Mill.) plug transplants were grown for 17 days either under a 24-hour photoperiod with a photosynthetic photon flux (<jats:italic>PPF</jats:italic>) of 200 μmol·m<jats:sup>-2</jats:sup>·s<jats:sup>-1</jats:sup> or under a 16-hour photoperiod with a <jats:italic>PPF</jats:italic> of 300 μmol·m<jats:sup>-2</jats:sup>·s<jats:sup>-1</jats:sup>, resulting in the same daily integrated PPF (17.3 mol·m<jats:sup>-2</jats:sup>). Air temperatures were alternated between 28 °C during the first 16 hours and 16 °C for the subsequent 8 hours of each day. Fresh weight, dry weight and leaf area were 41%, 25%, and 64% greater, respectively, under the 24-hour photoperiod than under the 16-hour photoperiod. Physiological disorders (e.g., chlorosis and/or necrosis) were not observed under the 24-hour photoperiod, probably due to the alternating air temperature. Floral development of plants originating from both treatments did not differ significantly. Electric energy use efficiency of the closed system was 9% greater under the 24-hour photoperiod than under the 16-hour photoperiod. These results suggest that using a 24-hour photoperiod with relatively low <jats:italic>PPF</jats:italic> can reduce both initial and operational costs for transplant production in a closed system due to the reduction in the number of lamps.</jats:p>

Study of the beneficial effects of green light on lettuce grown under short‐term continuous red and blue light‐emitting diodes

“…Continuous light (CL) is a potential method to increase crop production in a protected environment and is also a useful tool for speeding crop selection (Sysoeva et al , Velez‐Ramirez et al ). Therefore, the use of CL has been widely studied in many species, including tomato (Ohyama et al , Velez‐Ramirez et al ), eggplant (Murage et al ), lettuce (Sysoeva et al ) and pepper (Demers and Gosselin ). However, CL has been shown to induce negative effects in several plant species, and the most visible negative effect induced by CL is chlorosis (Tibbitts et al , Pettersen et al ).…”

Recovery of tomato ( Solanum lycopersicum L.) leaves from continuous light induced injury

“…Furthermore, the use of a 24 h photoperiod with lower photosynthetic photon flux density (PPFD) can reduce both the initial and operational cost for production by reducing the number of lamps (Oda et al, 1989;Ohyama et al, 2005) and increase early vegetative growth and fruit yield in tomato (Demers et al, 1998).…”

Immediate and delayed effects of diurnal temperature drops on growth and reproductive development of tomato plants grown under continuous lighting

“…The accelerated development under the action of thermoperiod with low night temperatures correlated with values of mean daily temperature. For example, the rate of flower development was higher at lower daily average temper ature [15]. The lack of acceleration of reproductive development under DROP treatment compared to control conditions in our experiments might be due to insignificant difference between these treatments in terms of the average daily temperature, which equaled to 24°C for control conditions and 24.7°C in the case of 24 h + DROP treatment.…”

“…Application of DROP under CL over the pre reproductive period did not accelerate the reproduc tive plant development compared to that of control plants, although such acceleration was noted in plants subjected to the thermoperiod [15]. The accelerated development under the action of thermoperiod with low night temperatures correlated with values of mean daily temperature.…”

“…It is known from the literature that diurnal temper ature fluctuations (thermoperiod with more than 8°C daily change) prevent to some extent the development of leaf chlorosis under CL in some Solanaceae species including tomato [12][13][14][15]. We showed previously that short term diurnal temperature drops to cold harden ing values (DROP treatment) prevent the injury of tomato leaves caused by CL [16], without delaying plant development.…”