Vertical Farming with Phycocyanin-rich Spirulina Extract

by Jeet Varia, Cedric Kamaleson, and Leonard Lerer

Climate change, food security challenges, and environmental degradation due to large-scale outdoor industrial farming make it vital to explore moving food production closer to large, urban populations.

There has been a surge in public, government, and investor interest in controlled environment agriculture (CEA) and multi-layer plant production, generally known as vertical farming (VF). Vertical farms can be operated using high levels of automation including phenotype-driven, artificial intelligence (AI)-based management tools for production inputs, including lighting, environmental conditions, and nutrient delivery.

VF has rapidly transitioned from a promising food production concept into an accepted technology for providing fresh leafy greens to our cities and is a potential solution for producing high-quality, accessible, and climate-friendly nutrition for growing urban populations. However, to realize VF’s potential as a sustainable food source, innovative technologies are required to ensure that it can be industrialized on a massive scale and extended beyond leafy greens and fruits into the production of food staples or row crops.

While technological advances have improved the energy efficiency of VF lighting systems, there has been insufficient research into biostimulation as an approach to reduce energy needs and improve crop quality and yield.

A research team at Back of the Yards Algae Sciences conducted a controlled trial to investigate the application of a phycocyanin-rich spirulina extract (PRSE) as a biostimulant in hydroponically grown, vertically farmed lettuce (Salanova® Lactuca sativa and Salanova® Red Crisp). Phenotype analysis for Salanova® Red Crisp with PRSE application showed a reduced time from seed to harvest by 6 days, increased yield by 12.5%, and improved antioxidant flavonoid levels.

Metagenomic analysis of the microbial community of the nutrient solution for Salanova® Lactuca sativa cultivation indicated a 62% reduction in the bacterial population for the PRSE treatment group (vs. 0.017% increase for the control group). An increase in the overall bacterial diversity and evenness was found in the PRSE treatment group as compared to a decrease in these parameters for the control group.

Conclusions

This preliminary study reveals the utility of PRSE for plant growth promotion, improvement in crop yield, and potential prebiotic activity in hydroponic vertical farming. Moreover, it demonstrates that microalgae-derived biostimulants may play an important role in improving the economic and environmental sustainability of VF.

The long-term economic, environmental, and social impact of VF will largely be determined by its economic sustainability. This preliminary study showed that the application of PRSE enhanced growth velocity and yield in hydroponically grown lettuce. Metagenomic analysis of the nutrient solution also indicated that PRSE influences the microbial community, with an overall decrease in bacterial population and simultaneous increase in diversity and richness.

While further research is required, the results indicate that PRSE may be an important and innovative production input contributing to the economic sustainability of VF. Besides showing the potential of PRSE to reduce growing time, thereby saving energy, this study provides initial evidence that it also improves product quality, i.e., nutritional density of flavonoids.

The availability of effective biostimulants will support deploying VF to enhance food security in areas with limited farmland and this could include the cultivation of food staples such as wheat and corn. Finally, this study of the application of PRSE in VF also provides some early support for the broader consideration of the role of combinations of microorganism extracts including bacteria, mycelia, and mycorrhizae as biostimulants.