Analyses of Photosynthesis and Productivity of Paprika (Capsicum annuum L. Cupra) using Sulfur Plasma and High-Pressure Sodium Lamps as Supplemental Light Sources

Abstract

Supplemental lighting with artificial light sources is a practical method that enables normal growth and enhances the yield and quality of products. The objective of this study was to investigate the effect of sulfur plasma (SP) and high-pressure sodium (HPS) lamps as supplemental lighting sources on the growth and yield of paprika in greenhouses. For the SP and HPS lamps, the effects of primary lighting on plant growth was compared in walk chamber and that of supplemental lighting also compared in greenhouse. In the growth chamber

plant height, leaf area, stem diameter, number of leaves, fresh weight, and dry weight were measured every week at the SP and HPS lamps from 2 weeks after transplanting. In the greenhouse, no supplemental lighting (only sun light) was considered as the control. The supplemental lights were turned on when outside radiation became below 100 W m-2 from 07:00 to 21:00. From 3 weeks after supplemental lighting, the growth was measured every week while the number and weight of paprika fruits measured every two weeks. In the growth chamber, the growth of paprika was better at the SP lamps than the HPS lamps due to higher photosynthetic rate at the SP lamps than at the HPS lamps. In the greenhouse, the yield was higher at the supplemental lightings of the HPS and SP lamps than at the control, while the proportion of marketable yield was lower at the supplemental lightings than at the control. No significant differences were observed in the plant height, number of node, leaf length and fresh and dry weights between the SP and HPS treatments. However, at harvest, the number of fruits rather than the weight of fruits was higher at the SP lamps. It was suggested that new cultivation methods including fertigation strategy are needed to reflect the effect of supplementary lighting on plant growth.