A study on the early growth and development of salt marsh plants for salt marsh restoration

다국어 초록 (Multilingual Abstract)

Salt marsh ecosystems are essential blue carbon systems that provide powerful carbon sequestration, shoreline stabilization, and ecological functions. To restore declining salt marshes in Korea, the stable cultivation and establishment of salt marsh plants, particularly Suaeda japonica, a dominant intertidal species, is essential. This study investigated the early growth physiology of S. japonica through two complementary experiments: (1) the seedling cultivation study examining the effects of Sargassum horneri extract (SHE) under various salinity conditions, and (2) the test-bed experiment assessing seedling establishment and physiological responses in a natural intertidal environment.
SHE significantly reduced oxidative stress and improved photosynthetic stability by reducing hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) levels and increasing catalase (CAT) and glutathione reductase (GR) activities under high salinity conditions. This treatment effectively reduced salinity-induced chlorophyll degradation and stabilized carotenoid pigments, thereby improving early seedling growth and development. In test-bed experiments, direct seeding failed, but transplanted seedlings were established successfully. SHE pretreatment increased shoot length in an artificially created test-bed, demonstrating its effectiveness in enhancing seedling resilience under natural environmental variability. Sediment characteristics and hydrological exposure were key determinants of growth, with higher growth observed on structured uplands compared to natural tidal flat surfaces.
Overall, present results provided scientific evidence that seaweed derived biostimulants can enhance early growth, physiological tolerance, and establish reliability of salt marsh plants. This study supports the idea that seedling-based restoration strategies are an effective approach for enhancing vegetation recovery, sediment stabilization, and blue carbon capacity in Korean tidal flats.

목차 (Table of Contents)

• Abstract i
• Table of Contents iii
• List of Tables vi
• List of Figures vii
• Chapter 1. Introduction 1
• 1.1. Blue carbon ecosystems 1
• 1.2. Salt marshes 2
• 1.3. Salt marsh plants 4
• 1.4. Biostimulants 6
• Chapter 2. Effect of Sargassum horneri extract on the growth and salt tolerance of Suaeda japonica, a salt marsh plant, under different salinity conditions 9
• 2.1. Introduction 9
• 2.2. Materials and methods 11
• 2.2.1. Seedling preparation 11
• 2.2.2. Experimental treatments 12
• 2.2.3. Growth measurements and sample collection 14
• 2.2.4. Pigments analysis 16
• 2.2.5. Oxidative stress markers analysis 17
• 2.2.6. Antioxidant activity analysis 18
• 2.2.7. Statistical analysis 19
• 2.3. Results 20
• 2.3.1. Plant growth 20
• 2.3.2. Pigments 23
• 2.3.3. Antioxidant activity 26
• 2.3.4. Oxidative stress markers 29
• 2.4. Discussion 33
• Chapter 3. Salt marsh restoration using Suaeda japonica: Evaluation of seedling establishment and ecological effects 41
• 3.1. Introduction 41
• 3.2. Materials and methods 44
• 3.2.1. Seedling preparation 44
• 3.2.2. Test-bed establishment 44
• 3.2.3. Climatic and tidal conditions during experimental 48
• 3.2.4. Experimental design and treatments 50
• 3.2.5. Plant growth analysis 53
• 3.2.6. Pigments analysis 54
• 3.2.7. Photosynthetic efficiency analysis 55
• 3.2.8. Carbon, nitrogen composition in plant tissue analysis 56
• 3.2.9. Sediment physicochemical analysis 57
• 3.2.10. Statistical analysis 57
• 3.3. Results 58
• 3.3.1. Test-bed conditions and representative plant morphology 58
• 3.3.2. Plant growth 63
• 3.3.3. Pigments 66
• 3.3.4. Photosynthetic efficiency 69
• 3.3.5. Carbon, nitrogen composition in plant tissue 72
• 3.3.6. Sediment physicochemical analysis 75
• 3.4. Discussion 81
• Chapter 4. Conclusion 91
• Reference 93
• 국문초록 106