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EVEC Microgreens
Microgreens: Optimising Seed Density and Exploring the Influence of White Light and White Light Supplemented with UV-A Radiation
Microgreens are gaining prominence for their high nutritional value, rapid growth cycle, and suitability for controlled-environment agriculture (CEA). Amon
Shiva Dubey, Niamh Harbourne, Aisling Reilly, Daniel Hurley, Caroline Elliott‐Kingston
Plants · 2026 · https://doi.org/10.3390/plants15040635
Abstract
Microgreens are gaining prominence for their high nutritional value, rapid growth cycle, and suitability for controlled-environment agriculture (CEA). Among key agronomic factors, seed density critically influences both yield and microbial safety, and it also impacts production cost. This study evaluated: (1) the effects of various seed densities on the yield and microbial load of cress (Lepidium sativum L.), rocket (Eruca sativa), and pea (Pisum sativum L.); and (2) the influence of supplemental UV-A radiation on the biomass, microbial load, and phytochemical profile of pea microgreens. The study found that fresh biomass increased with increasing seed density across all species up to a threshold, achieving maximum yields at 12 seeds/cm2 for cress and rocket and 2 seeds/cm2 for pea. However, higher seed densities were also associated with increased levels of total aerobic bacteria (TAB), Enterobacteriaceae, and fungi, which could pose an increased risk of microbial hazards concerning food safety, e.g., TAB in cress increasing from 7.04 ± 0.09 to 7.94 ± 0.17 log10CFU/g as seed density increases from 6 to 14 seeds/cm2. Initially white light supplemented with UV-A recorded a lower yield (11 g) compared to white light (13 g), but the final biomass was comparable under both lights, with microbial load remaining stable at ~3.8–4.2 log10 CFU/g. A temporary increase in carotenoids exhibited significantly higher levels (2.00± 0.29 µg/mg DW) under white light supplemented with UV-A radiation compared to white light alone (1.48 ± 0.23 µg/mg DW). However, these increases were not maintained throughout the growing period. These results indicate that optimising seed density in these species is vital for balancing productivity and food safety, and continuous UV-A exposure did not lead to sustained higher phytochemical levels or reduced microbial load compared with white light alone.
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How to credit this work
Shiva Dubey; Niamh Harbourne; Aisling Reilly; Daniel Hurley; Caroline Elliott‐Kingston (2026). Microgreens: Optimising Seed Density and Exploring the Influence of White Light and White Light Supplemented with UV-A Radiation. Plants. https://doi.org/10.3390/plants15040635 Licensed under Creative Commons Attribution 4.0 (https://creativecommons.org/licenses/by/4.0/). Hosted by EVEC Athens (microgreens.org.gr). No changes were made to this article. Provided as-is, without warranties. EVEC Athens is not affiliated with, and this copy is not endorsed by, the authors or the publisher.
Explore this on our site
- How to grow it: Arugula microgreens — growing guide
- How to grow it: Cress microgreens — growing guide
- How to grow it: Pea microgreens — growing guide
- Related reading: International sanitary guidelines for the planting and distribution of microgreens and sprouts
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