Evaluation of Insect Frass, Few-Layer Graphene and Their Combination on Seed Germination and Early Seedling Growth of Rocket

The growing demand for sustainable agricultural practices has increased interest in bio-based fertilizers and nano-enabled materials for plant development. This study investigated the responses of rocket (Eruca sativa) to Frass Suspension (30 min), Frass Suspension (overnight), Few-Layer Graphene (FLG), and a combined Frass/FLG formulation at different application levels. Germination percentage and primary root length were evaluated in two independent experiments, followed by a descriptive post-transplantation assessment. Germination responses varied among treatments, application levels, and experiments, with no treatment consistently producing the highest germination percentage. The highest mean root length was recorded for FLG at 50% in the first experiment (119.14 mm) and FLG at 25% in the second experiment (94.37 mm). At Day 70, 30 of 130 transplanted seedlings remained alive, with the highest survivor counts observed for FLG 25% (8/10) and Frass/FLG 25% (7/10); however, these observations cannot establish treatment-specific survival effects. Overall, the results demonstrate treatment- and application-level-associated variation and substantial between-experiment variability, while providing no evidence that the combined Frass/FLG formulation consistently outperformed FLG alone. Further replicated studies are required to clarify the individual and combined contributions of frass and FLG.