Heating cost and low light limit greenhouse winter production in the north. Improved technologies can now support more efficient light delivery and interception. The greenhouse bell pepper cultivars Brocanto (yellow), Milena (orange) and Olly (red) were chosen to assess inter-canopy lighting with overhead high-pressure sodium irradiance. In addition to HPS, LED fixtures for in canopy placement were evaluated (GE current Arize® Integral). Plants were grown in a high-wire drip irrigation system using dutch bato buckets (17.7 L volume). The photoperiod was 16-h, day temperature 22 ± 2°C and reduced to 18 ± 2°C during the night. One or two horizontal LED bars were positioned and adjusted within 30 cm of the top of the plants throughout the study. In treatments with two LED bars, the bars were placed 30 cm (12 inches) apart. The intensity (400-700 nm) horizontally from the LEDs and measured at the location of the plant stems averaged 195 ± 30 µmol m-2s-1. Overhead HPS provided ~130 ± 20 µmol m-2s-1, 100 cm below the fixtures. Natural light was seasonally limited during the study. Seeds were sown on 29 Aug and one plant was transplanted into each container 50 d later (17 Oct). Lower leaves were removed as fruit ripened and the study was terminated at a plant height of ~180 to 200 cm. Colored peppers were first harvested 79 d from transplant (4 Jan) and the study was discontinued 8 weeks later. Plants grown with two LED bars produced higher yields than those with one bar or only HPS lighting. Olly produced 1.3 ± 0.09 kg under HPS, 2.2 ± 0.16 kg (one bar) and 3.2 ± 0.02 kg (2 bars) per plant while both Brocanto and Milena yielded 1.6 ± 0.19 kg under HPS, 2.3 ± 0.19 kg with one bar and 2.7 ± 0.09 kg (Milena) or 2.9 ± 0.10 kg (Brocanto) with two LED bars. The LEDs also increased the number of harvested peppers. For Olly, ten peppers were harvested on plants with only HPS and increased to 15 and 20 peppers with the LED bars. Six more peppers per plant were harvested with interlighting for Brocanto and Milena. The pepper size remained similar across treatments for Brocanto (197 ± 12.4 g) and Milena (170 ± 10.0 g). For Olly, the pepper size increased from 129 ± 6.0 g (HPS) to 161 ± 5.4 g with two LED inter-canopy bars.
