ASHS 2025 Conference

Microgreens are young seedlings that are harvested between 7 and 21 days after germination with height of generally 2 to 4 inches depending on the species. They are considered to be nutrient-dense functional foods and have been reported to be rich in mineral nutrients such as calcium (Ca), magnesium (Mg), potassium (K) and iron (Fe) as well as health beneficial phytochemicals. Seed priming treatments have been used to activate metabolic activity within the seed and promote fast and uniform germination, which is critical in microgreen production. The objectives of this study were to assess the effect of four seed priming treatments on the shoot growth, visual quality, and mineral nutrient compositions of four herbal microgreen species grown on hydroponic mats made from jute fibers. Four microgreen species including chives (Allium schoenoprasum), dill (Anethum graveolens), scallion (Allium fistulosum) and shiso (Perilla frutescens var. crispa) were used in this study. Four priming treatments were applied including hydro priming with distilled water (20-22°C), chemical priming with hydrogen peroxide (0.3%), biostimulant priming with a plant growth promoting rhizobacteria (PGPR) (0.528 ml·L-1), and another biostimulant derived from kelp extract (5 ml·L-1). Microgreen seeds were soaked for 6 hours in each of the priming solutions and then allowed to dry overnight to their original weight. The control treatment consisted of non-primed raw seeds. Data including germination percentage, shoot height, visual quality, fresh and dry shoot weights, shoot color, and mineral nutrients were all collected. Fresh shoot weight was significantly affected by the interaction between microgreen species and priming treatment. The four priming treatments and control resulted in similar fresh shoot weights in chives, scallion, and shiso. Dill from the control treatment had a significantly higher fresh shoot weight of 1302 g·m-2 compared to kelp extract, PGPR, and hydropriming with weights of 737 g·m-2, 740.7 g·m-2, and 345.8 g·m-2, respectively. Microgreen shoot height was affected by species and priming treatment separately with no interaction. The non-priming control produced shoots with height of 6.9 cm, significantly higher than those from the kelp extract or the hydropriming treatment with heights of 6.3 cm and 6.2 cm, respectively. Chives produced the lowest shoot height of 5.3 cm compared to dill, scallion and shiso with shoot heights of 6.9 cm, 7.0 cm, and 6.8 cm, respectively.