Activated Carbon Regulated Polyvinyl Alcohol Hydrogel for Soilless Culture

The development of high-performance soilless substrates is urgently needed for sustainable agriculture. Polyvinyl alcohol (PVA) hydrogel, as a biocompatible material, can avoid environmental pollution and has effects such as water retention. However, pure PVA hydrogel exhibits poor mechanical strength and is prone to fracture, limiting its direct application in plant cultivation. Therefore, in this study, PVA hydrogels with different activated carbon (AC) contents were prepared by introducing AC as a filler material using the solution blending-freeze-thaw cycling method, and their properties and potential applications in soilless culture were systematically investigated. It was demonstrated that the addition of AC significantly improved the microstructure of the hydrogels and enhanced their mechanical properties through various characterizations. Moreover, plant growth experiments show that hydrogels with 3% AC content could effectively promote the germination rate and growth of sesame seedlings, which are attributed to the porous structure of AC to optimize water and nutrient transport. This study provides a proof-of-concept for a tunable, AC-reinforced PVA hydrogel strategy for the development of soilless substrates that combine mechanical properties, water retention and growth promotion.