Managing Greenhouse Bell Peppers for Optimal Yield

Colored bell peppers (Capsicum annuum) are receiving increasing interest as a profitable greenhouse produced crop. To optimize greenhouse space and productivity, the plants are commonly trellised and pruned. A common production approach is to train two lateral shoots into a “V” system off the main stem. Pruning recommendations vary in respect to length and number of leaves to keep on the lateral branches developing on the two trellised stems. An experiment was therefore initiated to determine the effects of pruning method on yield in a two-stem trellising system. The six cultivars Fantasy (red), Fascinato (red), Organela (orange), Paramo (orange), Striker (yellow) and Tenato (yellow) were selected. The study was completed in a greenhouse covered with the acrylic material DEGLAS® and conducted from Feb. 17 through Sept. 28. Supplemental lighting from high pressure sodium lamps was provided when outside ambient light dropped below 400 W·m^-2 between 6:00 AM to 10:00 PM. The plants were grown in a vertical high-wire drip irrigation system using dutch (bato) buckets (17.7 L volume) filled with a 50/50 mixture of perlite and a peatlite medium (Pro-Mix BX). The plants were divided into two treatment groups (n=12) for the evaluation of pruning techniques. One set of plants was pruned so that each lateral side-stem was topped over one leaf while in the second group, three leaves were left. The fruits were harvested at maturity with at least 90 percent color formation. Fantasy, Fascinato and Paramo produced significantly higher yields in the three-leaf approach. There were no differences in yield for Orangela, Striker or Tenato. During the production period from June through September, the highest yields were observed for the red peppers Fantasy (4.7 ± 0.82 kg per plant) and Fascinato (4.5 ± 0.69 kg per plant) in the three-leaf system. In contrast, the yield for the yellow peppers Striker and Tenato was 4.2 ± 0.67 and 4.0 ± 0.74 kg per plant independent of the pruning technique. Orangela produced 3.7 ± 0.55 kg per plant in both systems while Paramo (4.0 ± 0.68 kg) was more productive in the three-leaf approach. Size of individual peppers was similar for each cultivar independent of pruning technique. For those cultivars with higher yields, the increase was due to the development of additional, not larger, peppers. The average weight for a single pepper varied from 196 ± 39.1 grams for Paramo to 245 ± 47.2 grams for Striker.