Today, the huge expansion throughout the world in the build of large greenhouse units, from Mexico to China, Kazakistan to Canada to Qatar, is more than evident. Cravo Equipment Ltd, Canada, reports a doubling of its global business with retractable roof greenhouses in 2018, despite being in business for over 40 years. See HORTCOM theme ‘Protected Cultivation’. There follows a great need for well qualified horticultural technicians in white coats, data programmers and business managers, fewer and fewer less qualified workers, all a far cry from the tradition grower (the business used to be called plant husbandry!). Article by Errol W Hewett, entitled ‘Horticultural science in crisis: where are the graduates required to assure its future? Published in Chronica Horticulturae, Volume 55, November 2, 2015. Although four years have passed, up-to-date statistics will reveal the same problem. Some Cravo devlopments for cherries, for berry fruits, for research into insect protection and control
One major reason for such increase in protected cultivation is due to climate change and the uncertain big swings in damaging weather conditions. Insect damage, drought and flooding in the Emilia Romagna region of Italy has halved the fruit production and compromised potato and onion crops in 2019. Another important reason for the increase in protected cultivation is to reduce logistics costs by creating much closer ties with local demand through tight programs of supply and quality control with greater opportunities for promoting local or national produce with the final consumers. Innovative technology also permits the production of crops all-year-round or out of season, utilizing waste heat from various sources (e.g. breweries, power stations, recycling plants).
Last but not least, modern efficient production technology mainly using hydroculture, LED lighting, systems of recycling and new construction design allow the construction of greenhouses almost everywhere; vertical constructions or on top of sky-scrapers in urban areas, or on marginal land unsuitable for agriculture, even floating on bodies of water, underground or in areas of desert. This has led major investment companies and pension funds to enter the world of horticulture in a big way.
But can we help feed the world with just tomatoes? Also evident is that this explosion in protected cultivation is limited to just a handful of crops that adapt well to hydroculture; tomatoes and lettuce everywhere, some sweet peppers, cucumber, spinach, culinary herbs and strawberries, not forgetting marijuana. Hydroponic culture reduces the consumption of water and fertilizers, finished plants are highly uniform and almost all aspects of production can be automated, even robot harvesting and packaging is just round the corner. But when all this production comes on stream, what will happen to the prices for tomatoes and these other crops, despite the logistics?
Scientists should now be looking at adapting many other high value field crops for protected cultivation. WUR Wageningen University and Research have even been trialing the production of bananas in rock-wool and hydroculture in Holland. In general terms, research is demonstrating advantages of retractable roof greenhouses that provide ‘open sky’ conditions when the weather is good and protected conditions when adverse. Such conditions have proven ideal for tree fruits such as cherries, berry fruits (raspberries, blueberries, strawberries with significant increases in overall yield and fruit size. The production of ornamentals, shrubs (including containerized roses) and annuals has also been established. Following the construction of fixed structures, there is an increasing demand also for the use of protective netting against bad weather and insects. One well known Italian manufacturer is Arrigoni SpA. See image of protected cherry cultivation.