Source/Author/Date: Dr Lynette Morgan PhD, Suntec International Hydroponic Consultants, New Zealand, November 2008
Long Title: Comparison of Sure to Grow® Pads to 3 Other Growing Media for Production of Microgreens in a Standard NFT Tray Greenhouse System, Including Relative Growth rate Analysis and Postharvest Assessment, Arugula, Red Cabbage and Broccoli
The primary objective of this study was to compare the growth of 3 microgreens species (arugula, red cabbage and green broccoli), sown into 4 different pad/media products used in US commercial production, these being Cornell Peat-Lite Mix, horticultural grade perlite and vermiculite and the Sure to Grow® Pads for microgreens production.
Links: Suntec
While there appeared to be many interactions with regard to season, species and media/pad treatment, the STG product consistently produced the highest quality harvested product and had the least post harvest problems at completion of the shelf life assessment. Yield and relative growth rate results were mixed and appear to be dependant on species. The STG Pads produced significantly higher yields than perlite in the Arugula crop in both sowing dates, but there was no significant effect of media/pad treatment for yield with the red cabbage. Relative growth rate analysis results showed a general trend of the perlite treatment having lower fresh and dry weight accumulation.
Perlite consistently performed the poorest of all 4 media evaluated – in terms of yield, relative growth rate, product quality, particle contamination issues and disease occurrence. Peat-Lite, vermiculite and STG did not demonstrate any major contamination issues of the harvested product.
Peat-Lite, vermiculite and perlite developed isolated disease outbreaks under warm and humid growing conditions despite good hygiene and sterilised water used during production. STG treatments remained disease free during the course of this trial. This trial was run under optimal spring growing conditions and results may differ under less than optimal environmental conditions or where disease pressure may be high.
Media treatment had a significant effect on plant quality and post harvest shelf life. Vermiculite and perlite are prone to post harvest rots and yellowing. STG produced seedlings which are more compact, less elongated then other treatments with a greater shelf life and fewer post harvest problems.
Peat-Lite appeared to have a slight germination advantage which may be due to the presence of organic compounds contained in peat such as humic acids. These could be beneficial as additives to STG systems during the early stages of germination. Peat-Lite significantly increased the EC of the nutrient solution flowing through the system due to the presence of fertiliser salts in this media. STG was the only media which had no influence on solution EC or pH.
STG has a clear and significant advantage in the efficiency and management of NFT microgreens production systems including greatly reduced set up and removal times, ease of irrigation management, and effective control of root zone moisture levels.
It appears that different species of microgreens respond to the physical properties of these growing media in different ways – in this trial Arugula was the species which significantly and consistently produced greater yields as well as higher product quality in STG, while there was no significant effect of treatment on Red Cabbage.
Based on the findings of this trial, the most significant advantages of the STG product are in lower occurrence of disease during production and post harvest, ease of use, lower labour requirement for installation and removal, good physical root environment including drainage between irrigations and most importantly, improved microgreens product quality and greater shelf life.
Dr Lynette Morgan PhD
Suntec International Hydroponic Consultants