Effects of localised heating of regions adjacent to temperature-sensitive organs on growth and yield of winter-cultivated paprika ( Capsicum annuum L.) in a greenhouse

During winter, paprika (Capsicum annuum L.) plants are frequently exposed to suboptimal temperatures, which negatively affect leaf photosynthesis, transpiration, and root activity. Conventional greenhouse systems generally control the temperature of the entire greenhouse space, resulting in excessive energy consumption. To address this, organ-based localised heating that selectively regulates temperatures near temperature-sensitive organs provides an alternative approach to enhance plant growth and yield while maintaining energy efficiency. In this study, localised heating was evaluated by regulating the temperature near the root and reproductive organs. Four treatments were applied: no heating (Control), root-zone heating (RH), flower-fruit-adjacent heating (FH), and combined RH and FH (RFH). Heated water was circulated through pipes surrounding the substrate and the reproductive organs for RH and FH, respectively. The localised heating systems increased root-zone and flower–fruit-adjacent temperatures by approximately 6–7°C and 2–3°C, respectively. Localised heating significantly increased stomatal conductance and transpiration rate in the early morning. Fruit yield increased by 30%, 34%, and 70% in RH, FH, and RFH treatments, respectively, compared to the Control. These results indicate that organ-targeted localised heating can effectively enhance paprika growth and yield during winter cultivation while potentially reducing excessive energy consumption associated with whole-greenhouse heating.