Effects of Mineral Filler Composition on Pellet Properties, Seed Quality, and Seedling Establishment of Pelleted Chinese Cabbage Seeds

Seed pelleting improves seed handling and precision sowing, but its performance depends strongly on the physicochemical properties of filler materials. This study evaluated the effects of talc-based mineral filler combinations on pellet characteristics, germination, greenhouse emergence, seed vigor, and seedling growth of Chinese cabbage (Brassica rapa L. var. pekinensis). Talc (TC) was used alone or combined with bentonite (BE), calcium carbonate (CC), and diatomaceous earth (DE). Pellet physical properties, morphology, and surface elemental composition were analyzed using hardness measurements, porosity analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. TC + BE exhibited excessive swelling-driven water retention, prolonged disintegration time, and severe surface cracking, which were associated with reduced germination, delayed emergence, and poor seed vigor. In contrast, TC + CC + DE showed balanced physicochemical properties, including adequate hardness, moderate porosity, acceptable disintegration time, and improved water-holding capacity, producing superior greenhouse emergence while maintaining seedling growth comparable to the unpelleted control. Overall, successful seed pelleting depended on balancing structural integrity, water retention, and mass transfer properties within the pellet matrix. TC + CC + DE appears to be a promising formulation for Chinese cabbage seed pelleting.