Microgreens

Radish microgreens performed best with compost substrate. Fertilizer didn't help.

Sustainable Agriculture Student Research Project

 

Growing Medium and Fertilizer Effects on Microgreens

Manon Lee, Department of Sustainable Agriculture, 2023

 

Introduction

  • Microgreens consist of a central stem, cotyledon, and the first pair of true leaves (Figure 1).
  • Microgreens are used as nutritional supplements and for, visual, flavour and texture enhancement of food.
  • Growing media are soilless substrates for plants.
  • Growing media provide environmental consistency and hold water and nutrients, while reducing microbial populations. 
  • Some growers use fertilizer for microgreen production; others do not.
Harvestable crop stages for greens
Figure 1. Microgreens (second from left) are typically harvested 5-16 days after seeding. They are older than sprouts but younger than baby greens.

Objective

  • Determine how fertilizer and media affect the growth of radish microgreens

Materials and Methods

  • Completely Randomized factorial design (Figure 2)
    • 2 factors ( growing medium and fertilizer)
    • 6 treatments combinations
    • 3 replicates
Randomization scheme for factorial study of growing medium and fertilizer effects on microgreens
Figure 2. Randomization scheme for factorial study of growing medium and fertilizer effects on microgreens.
  • Growing medium factor levels (Figure 3)
    • Steel Mesh (On the Grow, TX)
    • Coconut Coir (Hydro Farm, Sri Lanka)
    • Compost (Spent mushroom manure, Canadian Tire)
  • Fertilizer factor levels
    • Fish Fertilizer (2-3-0) with tap water
    • Tap water only (Control)
  • Study site: Climate-controlled room in the Institute for Sustainable Horticulture Lab on KPU's Langley campus (Figure 4)
Seeded trays with different growing media
Figure 3. Seeded trays of growing media. 
Climate controlled growing room at Institute for Sustainable Horticulture
Figure 4. Climate controlled growing room at Institute for Sustainable Horticulture laboratory.
  • Management Timeline
    • Day 1: Seeded. Weights placed on top tray.
    • Day 4:  24-hour blackout for plant elongation
    • Day 9:  Harvested
    • Day 16: Dried and weighed
  • Statistical Analysis
    • Multi-factor ANOVA in jamovi interface for R
    • Means separation by Tukey test

Results

  • No significant effect of fertilizer (p = 0.24) (Figure 5).
Fertilizer effect on microgreens
Figure 5. Effect of fertilizer on dry weight of nine-day-old radish microgreens. Error bars denote standard error of each mean. No significant fertilizer effect was detected. 
  • Growing medium had a significant effect on radish growth (p < 0.001) (Figures 6, 7).
    • Highest growth in compost
    • Lowest growth in steel mesh
    • Intermediate growth in coconut coir
Growing media effect on microgreens
Figure 6. Dry weight of radish microgreens by growing medium (n = 6). Error bars denote standard error. Means labelled with the same letter do not differ significantly (Tukey test, α = 0.05).
Microgreens in compost and steel mesh media
Figure 7. Nine day-old microgreens in compost (left) and steel mesh media (right).
  • No significant interaction between growing medium and fertilizer (p = 0.41) (Figure 8)
    • No evidence that fertilizer influences the effect of growing media
    • No evidence that growing medium influences the effect of fertilizer
Growing medium * Fertilizer interaction
Figure 8. Growing medium * fertilizer interaction plot. Error bars denote standard error of each mean. No significant interaction was detected.

Conclusion

  • For the rate of application used, 9 day old radish not old enough to need fertilizer.
  • Trays in the mesh studies were not heavy enough to reach the reservoirs of water in the tray below which likely resulted in them drying out and dying.
  • Compost was the best growing medium followed by coco coir. Mesh performed very poorly.

Acknowledgements

Micheal Bomford and Sahar Zandieh for guidance and planning in carrying out of the experiment. Lisa Wegener and Deborah Henderson for the generous use of the Institute of Sustainable Horticulture Labs and assistance in executing the experiment.