Commercial Seedling Production in the United Kingdom Using Fluorescent Lamps

Lighting for Greenhouse Vegetable Production – An Overview

“…Using equal PPFD, Tibbits et al (1983) found no yield differences in lettuce grown (Grimstad 1982 (Newton 1973 (Helson 1965), and fluorescent lighting has been used for commercial seedling production (Newton 1981). Low-and high-pressure sodium lamps have also bee:n used, although there can be problems with heat dissipation (Chiang 1983) and spectral quality.…”

“…Lower PAR from highpressure sodium does not appear to harm tomato seedlin,g qualig (Skapski and Rudawy 1981), but may reduce calcium uptake in comparison with fluorescent lamps (Tremblay et al 1988a). Inlensive, mechanized, transplant production in artifrcially lit growth rooms is now possible (Newton 1981;Klapwijk 1986), and economically feasible (Meyer 1981) Bruggink 1987 (Bradley and Janes 1985). Tomato transplants require a nyctoperiod of 4 h to prevent these symptoms (Klapwijk 1986).…”

“…However, studies have found early yields of tomato are approximately doubled through long-term lighting through the nursery period (Canham 1972;Boivin et al 1987), and total yields are either unaffected (Boivin et al 1986) or may be increased (Boivin et al 1987). In Britain, growers use supplemental lights for up to 4 wk in tomato and cucumber, and through to harvest in lettuce (Newton 1981;Electricity Council 1987 (Nilwik 1981 (Blain et al 1987). PI below 20 W m-'had little effect on vield.…”