Microgreens are an emerging functional food that is sought after due to dense nutrient compositions as well as vibrant colors and textures. Seed contamination is one of the major food safety concerns as microgreens are consumed raw. Plant pathogenic diseases are also a concern as these can cause a reduction in the growth and quality of the crop. Seed sanitation methods should effectively reduce microbial load with minimal adverse effects on seed germination. The objective of this study was to investigate the effect of four seed sanitizing treatments on germination, shoot production and mineral nutrient concentrations of four microgreen species including chive (Allium schoenoprasum), shiso (Perilla frutescens var. crispa), scallion (Allium fistulosum) and dill (Anethum graveolens). Microgreen seeds were subject to four sanitizing treatments including: Tsunami 100 (400 ppm, 5 min), hydrogen peroxide (3%, 5 min), vinegar (1%, 15 min), and hot water (85°C, 10 sec). Seeds which were treated with deionized water for 10 min were considered to be the control. The microgreens were grown in a greenhouse and were planted into a peat-based substrate and a jute fiber mat in January 2024. Prior to greenhouse production, a germination test was conducted to investigate germination percentage of seeds for each species in response to the four sanitizing treatments or control. Microgreens were assessed for germination, shoot coverage, shoot height, fresh and dry shoot weight, and mineral nutrient concentrations. There was a significant interaction between microgreen species and the sanitizing treatment on fresh and dry shoot weight. The lowest fresh shoot weight for the three species chive, scallion and shiso was 938.2 g·m-2, 976 g·m-2, 907.8 g·m-2, respectively when treated with hot water, with the other three sanitizing treatments and control resulting in statistically similar fresh shoot weights. Dill microgreens showed little difference in fresh shoot weight among the five sanitizing treatments with values ranging from 506.4 g·m-2 in hot water to 868.2 g·m-2 in control. Sanitizing treatment and substrate type both had a significant effect on the shoot height of tested microgreens. Hot water treated microgreens produced the shortest shoots with a mean shoot height of 7.7 cm regardless of species or substrate type. The other four sanitizing treatments produced statistically similar shoot heights ranging from 8.01 cm with vinegar to 8.1 cm with Tsunami 100. The peat substrate increased overall shoot length in tested microgreens compared with jute fiber mats regardless of sanitizing treatment or species.
