Tecnologie innovative di pre-coltivazione di specie forestali basate su fonti luminose LED
Author(s)
Marras, Tatiana
Date Issued
June 27, 2016
Type
Doctoral Thesis
Abstract
The possibility of cultivating plants under artificial lights has fascinated men since the beginning of XX century. The introduction of LEDs led to a drastic change, thanks to the lower energy consumption and heat emission. The greater evolution in the field of indoor cultivation systems is represented by the plant factories, that are closed growth systems able to produce high quality plants during all year round, thanks to an artificial control of environmental conditions. While the indoor cultivation of vegetables is developing fast, the cultivation of forest species is still limited. The Zephyr EU-project (Zero Impact Innovative Technology in Forest Plant Production), funded by Horizon 2020, started in 2012 with the aim of introducing an innovative technology inspired by the plant factory concept for the precultivation of forest seedlings from seeds. The production unit is transportable, zero-impact, independent from outdoor environmental conditions and equipped with LED lights characterized by the emission of broad continuous spectra optimal for promoting plant photosynthesis. First aim of this thesis, developed within the Zephyr EU-project, was the definition of germination protocols for the following species: Corylus avellana L., Frangula azorica Grubov, Fraxinus excelsior L., Fraxinus ornus L., Hypericum foliosum Aiton, Laurus azorica (Seub.) Franco, Morella Faya (Aiton) Wilbur, Platanus orientalis L., Prunus lusitanica L. ssp. azorica (Mouillefert) Franco, Quercus suber L., Taxus baccata L. Among them, Corylus avellana L., Fraxinus excelsior L., Platanus orientalis L. and Quercus suber L. were then indoor cultivated, testing 5 LED spectra and 1 fluorescent spectrum. All the species showed good growth performances under artificial lights, evaluated through the analysis of morphometric and microscopic parameters, without any stress symptoms, with the exception of P. orientalis. In particular, LEDs resulted to be better than fluorescent lights in promoting plant growth. Apart from oriental plane, the other 3 species were then transferred for 1 year into a greenhouse before the transplant in the open field, showing that the effects of LED spectra on certain parameters tend to disappear after a few months after the exposure to natural sunlight. Referring to oriental plane and cork oak, some studies were also carried on in natural forests, in order to analyze, in terms of quality and quantity, the best light conditions for the growth of natural regeneration. In both cases seedlings appeared to be exposed to alternating light conditions (light/shadow) during a day. So the classical definition of heliophilia, as feature of plants growing better if exposed to full sunlight, is not fit for seedlings. It is therefore possible to artificially cultivate these species at low light intensity, too. In the cork oak forest a significant difference in terms of germination and emergence percentage was identified between points exposed to direct sunlight in the hottest time of the day and shadowed points. The link between temperature and phenology was confirmed comparing the natural growth cycle of cork oak into the forest with that typical of greenhouse and growth chamber. Into a growth chamber, the constant temperature (independently form the seasons) makes
the growth cycles faster and seedlings result to be higher than in natural or semi-natural conditions. The so obtained results show the high potential of LEDs as light sources for forest species precultivation, once defined a right germination and cultivation protocol.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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