2017 ASHS Annual Conference
Environmental Practices to Optimize the Growth, Development, and Nutritional Quality of Microgreens
Environmental Practices to Optimize the Growth, Development, and Nutritional Quality of Microgreens
Wednesday, September 20, 2017: 9:15 AM
Kohala 1 (Hilton Waikoloa Village)
Microgreens are young, tender and edible crops harvested shortly after emergence of the first true leaf. Increasing popularity has fueled cultivation in a variety of production environments. Carbon dioxide (CO2) enrichment is often used in greenhouses and sole-source lighting facilities to reduce the need for supplemental lighting, but little information is available on the response of microgreens to both light and CO2. Our objective was to evaluate the effects of varying daily light integral (DLI) and CO2 enrichment on the growth and nutritional characteristics of microgreens. Trials were conducted in controlled environment chambers modified for CO2 control. Three species: arugula (Eruca. sativa L.), mizuna (Brassica. rapa L. var. japonica) and mustard [Brassica. juncea (L.) Czern. ‘Garnet Giant’], received a combination of four DLI (3, 6, 9 & 12 moles•m-2•d-1) by four CO2 (400, 600, 800 & 1000ppm) treatments. Within each treatment combination there were 12 replicates with 3 experimental replications over time. Data was analyzed in a one-way mixed effects ANOVA at P < 0.05. Treatments were evaluated for their effects on plant height, fresh weight (FW), dry weight (DW), days to harvest (DTH), total phenolics and flavonoids. Results for FW varied by species as DLI increased from 3 to 12 mol•m-2•d-1. Mizuna and mustard exhibited linear increases in yield with percent FW increasing by 27% for mizuna and 35% for mustard as DLI increased from 3 to 12 mol•m-2•d-1 at 400 ppm CO2. Arugula increased in a quadratic fashion with reduced gains in yield above 9 mol•m-2•d-1. For all species the response of FW to CO2 was linear between 400 and 1000 ppm with an average yield increase of 11% as CO2 increased from 400 to 1000 ppm. For all species, DTH decreased by two days in a quadratic fashion, as DLI increased from 3 to 12 mol•m-2•d-1. Total phenolics exhibited a species-specific linear increase with increasing DLI as well as an interaction between DLI and CO2 that was independent of species. For example, arugula contained the highest concentration of total phenolics at 105.26 mg•100 g-1 FW at 12 mol•m-2•d-1 and 1000 ppm: an increase of 29.43 mg•100 g-1 from 3 mol•m-2•d-1 and 1000 ppm. Results could aid growers of various operations determine how their growing environment has an effect on yield, days to harvest and nutritional quality of microgreens.