20 August 2024
Greening and growing
Research at the Horticulture Development Department in Ashtown has implemented a commercial vertical hydroponic system for growing leafy greens.
Research Officers Michael Gaffney and Zoia Awan are investigating hydroponic growth systems at Teagasc Food Research Centre, Ashtown. Photo credit: Iain White, Maxwell Photography
Vertical hydroponic farming is an innovative agricultural concept for food production. With the world’s population growing and rapidly urbanising, and expected to reach nearly 10 billion by 2050, vertical hydroponic production has a potential role to play in delivering food year-round, particularly in large population centres and colder climates.
Some of the reported benefits include greater yields in a shorter growing period, water and nutrient efficiency, maximising space efficiency, and production in a range of buildings – from warehouse-type buildings to glasshouse facilities. Due to the controlled nature of resources like light and nutrients to the crop, a homogenous crop can be achieved with consistent and predictable yields.
The term ‘hydroponics’ is a catch-all term that refers to a myriad of production systems that typically involve the delivery of water (irrigation) and water with added nutrients (fertigation) to a growing medium instead of soil. Aeroponics, deep water culture, nutrient film technique and wick systems are examples of some of these systems.
Reservoir knowledge
The research facilities at Teagasc Ashtown are based on the deep water culture system, where a separate reservoir is used to hold the nutrient and water solution. This system also contains an air pump which serves to oxygenate the water, preventing the roots from drowning.
Lael Walsh, Principal Investigator at Teagasc, explains: “The oxygen-nutrient-rich water is constantly circulated through a closed circulatory chamber where the roots of plants are suspended in solution. Seeds are germinated separately in a growing media – such as coir, peat, paper, etc. Then, at the second true leaf stage, they are equally spaced across a four-tier shelving system and receive a light regime with high-performance LED grow lights for typically 16-20 hours a day, depending on the envisaged production cycle.
Ventilation is important to keep air circulating, preventing moisture forming on the crop, which can lead to the development of fungal diseases.”
Setting the dose
This research is made possible through the Leaf No Waste project (SFI Future Innovator Prize 2022) awarded to TU Dublin and Teagasc. Some of the research trials conducted under the Leaf No Waste project have focused on cultivating sweet basil (Ocimum basilicum) with the purpose of understanding the effect of silicon-based biostimulant supplementation on hydroponically grown basil.
Zoia Awan, Research Officer at Teagasc, explains: “Although basil is well studied in more traditional hydroponic systems, the use of silicon biostimulant supplementation in hydroponically grown basil, and its benefits to plant production and crop shelf life post-harvest, are not well understood.”
One of the initial major challenges has been optimising the levels and forms of silicon required for positive plant growth. At the correct silicon dose there are notable, positive changes to plant physiology particularly increases in yield, shoot and root length.
Lael adds: “Our work on silicon doses was a really important, fundamental part of the research that we had to get right, particularly because many silicon products available on the market are optimised for soil production.”
In some instances, when optimising the concentrations for this type of production system, at higher silicon application rates we did observe reduced plant growth and excessive deposition on crop roots.”
Market value
In addition to the research on basil, other leafy greens have been grown in the system at Teagasc, including chard, different types of lettuce, kale, fennel and pak choi. These have been used for demonstration purposes at public events like Bord Bia Bloom and for education purposes, explains Principal Research Officer, Michael Gaffney.
“As part of our research and knowledge transfer function, it has been important for us to demonstrate different production systems and assess if they may be agronomically and economically feasible within the context of the Irish market,” says Michael.
The Leaf No Waste project evaluates silicon supplementation in a range of horticulture crops, production systems and tests different application methods. It also investigates product performance post-harvest in a range of packaging solutions. Finally, it evaluates the environmental impacts of production and packaging interventions using life cycle assessment.
Funding
This research forms part of The Leaf no Waste project, funded by SFI grant number 20/FIP/FD/8934P awarded to Technological University Dublin and Teagasc.
Acknowledgements
The contributors wish to acknowledge the collaboration with Lorraine Foley and Jesus Frias from Technological University Dublin in this project.
Contributors
Zoia Awan, Research Officer, Teagasc Food Research Centre, Ashtown.
Michael Gaffney, Principal Research Officer, Teagasc Food Research Centre, Ashtown.
Lael Walsh, Research Officer, Teagasc Food Research Centre, Ashtown.