GOHYDRO D4.3 Report on validation of microgreens production in operational settings
Creators: name: Cowden, Reed
name: Rusu, Teodor
Publisher: name: Zenodo
Year: 2023

description: The activity <em>Task 4.3 Validation of performance of low-cost hydroponic units in operational settings</em>, had as an objective - <em>To carry out pilot trials and provide feedback for the refinement and calibration of the GOhydro platform</em>. In order to fulfill this objective USAMV Cluj built 2 GOhydro platforms, identical, to be able to do experiments in parallel, both in semi-controlled conditions and in operational, uncontrolled conditions. The GOhydro platform was built considering the recommendations from <em>Deliverable 2.1 Multi-modal Sensor Kit Specifications and Requirements</em>. USAMV performed the experiment with the GOhydro platform in operational conditions, with 2 species: basil (2 varieties: Germaline Basilic Bio and Basil Grand Vert) and lettuce (3 varieties: Paris White, Little Gem and Lolla Rossa). The methodology used for the research was derived from the one described in the deliverable <em>D4.1 Trial protocols for microgreens production in hydroponic units</em>. The influence of the environmental conditions outside the microgreen’s cultivation spaces can influence the development of microgreens and their outcomes. That is why the external environmental data were also analyzed, using for this purpose the data collected by “Meteo Romania”. The growing conditions of the two species of microgreens (basil and lettuce) is specific to the conditions in the operational environment, being also influenced by the external environmental conditions, for example especially by cloudiness. Thus, environmental parameters were seen to fluctuate; for example, temperature was seen to oscillate by 3-7 °C, with atmospheric humidity oscillation of 8-15 %, and respectively a variable amount of light (of 135-1645 μmol m<sup>-2 </sup>s<sup>-1</sup>). The irrigation water had a constant temperature of 19-21 °C, a pH of 6.8-7, an electrical conductivity between 1.4-1.5 mS, and respectively a quantity of 6.4-6.5 mg L<sup>-1</sup> dissolved oxygen. By comparison with the Duncan test, we found that the best amount of Fresh Weight was provided by Basil, variety Germaline Basilic Bio, with 883.40 g/m<sup>2</sup>. Basil provides the highest amount of Dry Weight, with a distinctly significantly positive difference compared to the control (average). The same results after processing the data with the Duncan test were seen for the 2 varieties of basil regarding the highest Dry Weight results. Furthermore, the variability of the data recorded for total phenols was very high, with the statistical processing not highlighting results with a significant difference. We showed that lettuce contained 98-105 mg/kg, and basil 106-127 mg/kg total phenols. From the morphological analysis of plant development, both in basil and in lettuce, no disease attack was registered, due to the maintenance of the health of the water in the feed basin and a quantity of around 6.4-6.5 mg L<sup>-1</sup> of dissolved oxygen. An exception is made in the case of lettuce, the Paris White variety, which registered until harvest grade 4 in the degree of attack. Due to the higher thermal oscillations than in the case of the experiment under controlled conditions, the degree of attack was slightly higher. This is due exclusively to this variety in which the seed had an inadequate quality for the production of hydroponic microgreens. The conclusions of the experiment, which require the optimization of production procedures with the GOhydro platform, are related to the type of substrate used, the density of the microgreens culture, the attack by pathogens and the seed germination procedure. In Denmark, we varied two experimental factors (Seeding Density and Fertilization) for three species (Basil, Pea, and Coriander) of Microgreens to better understand ways to optimize production, as well as offer comparisons to the other methods of cultivation employed in previous Deliverables 1.2 and 4.2. In our experiments, we identified some key tradeoffs, such as the increase in Fresh Weight accumulation and the decrease in Dry Weight accumulation via fertilization. However, fertilization was also associated with increased Height and Leaf Area. Finally, we identified that there was a slight negative effect of fertilization on Microgreen Health. Overall, we have shown that, despite tradeoffs, it is likely that fertilization is a highly net-positive input for producing Microgreens. The primary auxiliary concern, identified in Deliverable 1.2, is controlling pH to ensure optimal nutrient uptake from the fertilization solution. Using the GOhydro sensor kit offers a key tool to allow this quantification to inform the user when they need to add in a pH buffer; having this sensor kit offers a large advantage compared to other methods, such as multi-daily tedious measurements by hand. Concerning our second experimental factor, Seeding Density, we identified that it was space efficient, but it did not produce 50% more biomass, even though it was sown with 50% more seed weight. There was therefore a slight inefficiency in output, but this was compensated for by increased space efficiency, as there were more Microgreens per square centimeter. If space is not limiting, we recommend a standard or lower seeding density; if space is limiting, we recommend a high seeding density. Overall, we have validated the previous methodological observations seen in previous deliverables by producing high-quality healthy Microgreens in uncontrolled environments. Overall, considering the two separate sets of results obtained from GOhydro’s two different pilot sites in Denmark and Romania, we shown some crucial Microgreen production dynamics. Firstly, we have shown the operational capacity of the GOhydro sensor kit, as we were able to successfully send real-time data from our pilot sites back to Greece. Secondly, we have elaborated on some important considerations in uncontrolled operational environments that can generally approximate the growing conditions of the average targeted user of the GOhydro products. Finally, both Romanian and Danish pilot sites have identified the large amount of species-specific variation; therefore, the selection of Microgreens to grow is an important first step for optimizing and parameterizing the growth environment. Therefore, overall, we have identified key production tradeoffs and pathways for Microgreen production that can be used by a variety of actors. Given specific constraints or operational considerations, we have identified tradeoffs and optimal pathways to produce the highest quality Microgreens. This deliverable followed previous work in Deliverables 1.2 and 4.2; in this case, our results have validated the use of GOhydro findings in a variety of environments, demonstrating the potential to be effectively used by a wide variety of users in different contexts and scales.