The Effects of Artificial Lighting during the Seedling Stage on the Yield Structure of Sweet Pepper from a Single Harvest

Abstract

Sweet pepper (Capsicum annuum L.) is a globally cultivated vegetable, whose yield is affected by light intensity and photoperiod. This paper aimed to determine the effects of the applied light treatments during the seedling stage on the pepper yield after being transplanted into a greenhouse. The study utilized a commercial sweet pepper variety known as the Morava cultivar. When the plants reached the phenophase of forming their first permanent leaves, they were placed in closed plant growth chambers and grown under the following light treatments: full-spectrum white light-emitting diodes (W-LEDs) as the control group, blue LEDs (B-LEDs), a combination of red and blue LEDs in a 1:1 ratio (RB-LEDs), and red LEDs (R-LEDs), with a photoperiod of 12 hours of light and 12 hours of darkness, at a temperature of 23 ± 2°C. After 20 and 27 days of cultivation in these conditions, pepper seedlings were transplanted into bigger plastic pots and removed to the greenhouse, where plants were cultivated for the next 51 and 44 days, respectively. Fruits were picked in a single harvest, and the number of fruits, the yield and its structure, depending on the fruit color stages, were determined. Our results show that light treatments significantly influenced the total number of red fruits, while the length of exposure to light treatments significantly increased red fruit yield. The highest number of red fruits was observed in plants grown under RB-LEDs and R-LEDs, while the highest red fruit yield was achieved in plants grown under R-LEDs for 27 days. The number of yellow fruits was not affected by applied treatments, however, the interaction between light treatments and length of exposure to light treatments significantly influenced yellow fruit yield; it was the highest in plants grown under W-LEDs and B-LEDs for 20 days