An Analysis of the Growth and Photosynthetic Responses of Potted <italic>Veronica pusanensis</italic> Y.N.Lee according to the Shading Levels

Abstract

Background and objective: Veronica pusanensis, an endemic species of South Korea belonging to the Plantaginaceae family, is found in Busan, South Korea. Due to its high ornamental value, it is expected to be utilized as a flower crop. However, currently it is an endangered species with its habitats being destroyed and reduced.Methods: Therefore, in this study, we analyzed the growth and photosynthetic responses of potted plants of V. pusanensis under different shading levels to enable mass production. Polyethylene (PE) shading films were selected as the shading material, and shading levels were designed at 0, 35, 45, 60, 75, and 99%, respectively.Results: Results showed that shoot height, shoot width, ground cover, leaf length, leaf width, shoot fresh and dry weight, chlorophyll content (SPAD units), and chlorophyll fluorescence parameters Fv/Fm and PIABS were highest under the 35% shading level. This indicates that it is relatively more desirable to grow V. pusanensis in shade culture compared to under direct sunlight. Meanwhile, root fresh weight and dry weight were highest under the 0% shading level.Conclusion: Therefore, it is recommended to grow V. pusanensis under direct sunlight to significantly increase root biomass when the purpose is to facilitate rootage when transplanting plants for habitat restoration. On the other hand, for the cultivation of V. pusanensis as an ornamental flower crop, it is recommended to grow the plants under the 35% shading level to significantly increase plant sizes and maintain ensure the proper functioning of photosynthetic responses in photosystem II (PSII).