S08 - Session P4 - Impacts of environmental parameters on microgreen yield, nutrient content, and secondary metabolite production with a focus on light quantity and quality for Brassicaceae: a review

Authors: Reed Cowden *, Bhim Ghaley

Microgreens are gaining increasing attention because of their short growing cycle and their beneficial attributes such as high nutritional content, secondary metabolite production, and gastronomic applications. However, these attributes are dependent on species and environmental parameters making it difficult to prepare standard protocols to optimize production. Hence, our study objective was to synthesize information via a literature review (n=69 papers), detailing the current research findings on relationships between production environments and microgreen outputs. Results from all papers were presented on key production parameters (pH, temperature, relative humidity, electrical conductivity, and light factors, e.g.); we then narrowed the focus to the impacts of light quantity and quality on productivity, nutrient density, and plant compounds for the Brassicaceae family. Our Brassicaceae analysis showed that although total carotenoids were positively correlated with light quantity, increasing from 103 mg/kg at 10 mol/m 2 CLI (daily light integral*growing period) up to 270 mg/kg at 320 mol/m 2 , more variation was explained by light quality and species (53 mg/kg with red (660 nm) up to 1316 mg/kg with red (660 nm) and far red supplementation; B. oleracea average 101 mg/kg and 389 mg/kg for B. rapa , respectively). This pattern was also seen for anthocyanins, phenols, and other carotenoids, e.g. We found that an increase in light quantity increased dry matter production up to 300 mol/m 2 (R 2 =0.88), beyond which gains plateaued. Furthermore, our results showed that, although there is no single optimal light recipe for all varieties, there are recipes to enhance beneficial attributes that combine 5-15% blue light and 85-95% red light with supplementary far red or UV, at CLI around 170-190 mol/m 2 , depending on the desired outputs and variety used. The results from this paper allow interested entrepreneurs in microgreen production to have access to synthesized research findings with a particular focus on light effects on microgreens.