Dr MIKE NICHOLS is an inveterate traveller, attending horticulture conferences around the world as a speaker and journalist. In this article, he visits Singapore’s Sky Green project and conducts a training course in Thailand on aeroponics seed potato production.
Last year I was invited by the Thai Government to present a training course on soilless culture and hydroponics, with particular emphasis on aeroponics seed potato production. I immediately accepted, as Thailand is a delightful country to visit, and I had never been to Chiang Rai where the course was to be held. To me, Chiang Rai was famous as being the southern-most city in the ‘Golden Triangle’, the opium poppy production area of the 50s and 60s.
I flew via Singapore, in order to visit two projects of interest, The Sky Greens project, and the work of Dr He Jie at Nangyang Technological University using LEDs for plant factories.
I first learnt of the Sky Green project while at the Vertical Farming conference in Nottingham late last year, and wished to see it ‘in the flesh’. Singapore is very short of land, with five million people crammed into an area a little bigger than greater Auckland, and there is a very real concern for food security and for the efficient use of water resources, which come almost entirely from across the Causeway from Malaysia.
The Sky Greens project is a tremendous success from an engineering viewpoint, but has major problems horticulturally. Essentially, it comprises a number of tall tower-like greenhouses, each containing revolving belts, with troughs filled with plants. The revolving belt moves the plants in a circular motion on a vertical plane from the top to the bottom of the greenhouse over a period of 24 hours, though this is adjustable.
To me, this is very similar to the greenhouse developed by Ruthner for the 1963 Vienna Horticulture Exposition. It never caught on, but stimulated an interest in vertical farming, which has resulted in the current interest in plant factories. The main problem is like all vertical farming concepts—light inevitably becomes the limiting factor, and this is further complicated in Singapore by having the houses close to one another.
During my visit to Nangyang University I was shown a greenhouse in which two crops of kale were being grown. In one, the roots were at the ambient temperature, and in the other the roots were cooled with an aeroponics nutrient solution at 25 degrees Celsius. The difference was astronomical. Clearly, under Singapore’s high ambient temperatures, it is possible to grow excellent temperate vegetables simply by root cooling.
Dr He also showed me her LED lighting work with aeroponics, and I must admit to some concern about using aeroponics in a plant factory situation when a conventional hydroponic system might be just as effective. From a research viewpoint, however, the potential to examine the effect of root cooling on crop production under plant factory conditions would be of great interest. She insisted, however, that aeroponics was better than conventional, something I have yet to see confirmed in research reports apart from their studies in Singapore, undertaken in a very warm greenhouse.
And so to Thailand, the major purpose of my trip. I flew (via Bangkok) to the city of Chiang Rai, as noted earlier as the southern gateway to the notorious Golden Triangle, the source at that time of most of the world’s illicit opium. I took the opportunity of visiting the outstanding Opium Museum and was amazed to learn the major influence that the opium trade had on the politics of SE Asia in the 19th Century. The large quantities of opium being grown in India and sold in China by the British led to the severe addiction of many Chinese. The net result was to opium wars, and the Boxer rebellion, leading to the annexation of Hong Kong and the New Territories by Britain, leading to a considerable commercial advantage for Britain.
Aeroponics seed potato production
The purpose of my visit to Thailand, however, was not to improve my historical knowledge, but to provide a four-day training course on aeroponics seed potato production to Thai Department of Agricultural Scientists.
It may be recalled that in the late 90s, a Massey University graduate student (Ambalavanar Jegathees) undertook a research project (supervised by myself and Dr Bruce Christie) on the rapid propagation of high health seed potatoes. During the study he developed a method of obtaining a large number (in excess of 50) of small baby tubers from a single tissue culture cutting by using aeroponics. At about the same time, researchers in South Korea were also developing the technique. A seminar I presented to CIP in Peru also stimulated some interest, and CIP (the International Potato Centre) has now produced a technical booklet on the system.
During the training program, visits were made to aeroponics seed potato production projects in Chiang Rai and Tak, and it became increasingly clear that a system, which works well in a temperate greenhouse situation has a few problems in a warmer climate. For example, it is clear that in any environment it is far easier to have success putting roots on juvenile potato cuttings than on older cuttings.
It was also apparent that although in New Zealand stolons developed easily on the stems of the cutting, that in Thailand stolons do not develop readily, and without stolons there will be no (or very few) tubers. Stolon growth would appear to be very temperature dependant.
On a visit to Chiang Mai I was taken to visit a large (4ha) sweet pepper greenhouse operation. Built to a gull wing design and using Israeli technology (Netafim), it was a most impressive example of what can be achieved in the cooler parts of Thailand using modern technology. The houses were fully screened against insect pests, there was automatic ventilation, with the sides rolling up, leaving just the insect screens in place.
My final day in Bangkok was presenting a talk on ‘Plant Factories’, a look into the future but not too distant for cities like Bangkok with a rapidly increasing population. In fact, it was closer than I thought, as the Department of Agriculture showed me a plant factory comprising a fully insulated shipping container set up with lighting and irrigating systems provided by a South Korean company. The lighting was by fluorescent bulbs, and the irrigation system was NFT, both quite satisfactory for growing lettuce. Using LED lighting might have improved things, but the unit was not in use, due to the high electricity costs. Of course, having the equipment and being able to operate it efficiently are two very different things!
Over the years New Zealand in general (and Massey University in particular) has been involved in providing considerable technical assistance in agriculture to Thailand. For example, the first Professor of Agriculture at Khon Kaen University was funded by NZ Aid, and was seconded from Massey. This meant that the hospitality I received while in Thailand was outstanding.
We stand on the shoulders of those who go before us!
About the author
Dr Nichols is a retired University teacher from Massey University, New Zealand, and a regular contributor to Practical Hydroponics & Greenhouses magazine. Email: firstname.lastname@example.org Ω
(See inside the April 2015 issue for full pictorial)
PH&G April 2015 / Issue 154