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Integrated vertical aeroponic farming systems for vegetable production in space limited environments

He, J.
Acta horticulturae 2017 no.1176 pp. 25-36
Brassica juncea var. japonica, Brassica oleracea var. alboglabra, Brassica rapa subsp. chinensis, Brassica rapa subsp. nipposinica, Lactuca sativa, Ocimum basilicum, Perilla frutescens, aeroponics, aquaponics, basil, cities, climate change, crop rotation, energy, food security, greenhouses, hydroponics, imports, lettuce, light emitting diodes, light intensity, lighting, photosynthesis, population growth, rhizosphere, vegetable growing, vertical farming, Singapore
A growing population generates tremendous demand for food, especially of vegetables, in space limited cities such as Singapore. Rooftop and vertical farms integrated with various technologies, such as hydroponics and aquaponics, have been commercialized over the past few years in Singapore. However, to compensate for the lack of land space and an increasing population, Singapore needs to develop its own unique effective farming system that will be independent of eventual climate changes. Using aeroponic systems, our previous studies showed that cooling the root-zone (RZ) could produce all types of vegetables throughout the year. Currently, we have expanded Singapore's urban farming technology by successfully developing an LED-integrated vertical aeroponic farming (VAF) system that can be used both indoors and in greenhouses, for vegetable production. Other than providing sufficient and uniform light intensity to the plants, the factor key to the success of this VAF system is the provision of a low energy input engineering solution - the use of light emitting diodes (LEDs) - to enhance photosynthesis and maximise crop productivity. Our self-designed LED integrated VAF systems have been used to successfully grow lettuce (Lactuca sativa), Chinese broccoli (Brassica alboglabra), Nai Bai (Brassica chinensis), mizuna (Brassica juncea var. japonica) and culinary herbs, such as red and green Chinese basil (Perilla frutescens), and sweet basil (Ocimum basilicum). Experiments have also been carried out to identify optimal combinations, durations, and intensities of LED lighting for maximal vegetable production. Our results showed that all vegetables grown under LED lighting exhibited higher photosynthetic capacities, enhanced productivity, and higher crop rotation. However, we have also found that optimal growth conditions are species-dependent. In conclusion, although there are various vegetable farming strategies for space limited environments, extensive use of our LED integrated VAF systems would diminish our reliance on vegetable imports and enhance food security in Singapore.