Caratteristiche radiometriche di film fotoselettivi e fotoluminescenti

Radiometric characteristics of photoselective and photoluminescent films. Plastic films for protected cultivation capable of modifying the spectral distribution of the transmitted radiation can be developed with suitable radiometric characteristics in order to influence plant vegetative activity. In order to study such films, experimental tests were carried out at the experimental farm of the University of Bari in Valenzano (Bari, Italy), at latitude 41° 05' N, from December 2006 to September 2007. Two photoselective films (GREEN4% and GREEN2%), three photoluminescent films (RED,BLUE and RED-BLUE) and one low density polyethylene film were used as greenhouse coverings for cherry trees and peach trees. The photoselective films GREEN4% and GREEN2% alter the quality of solar radiation passing through the covering materials modifying the spectral distribution of the solar radiation in the wavelength range of the red radiation (R, 650-670 nm) and of the far red radiation (FR, 720-740 nm) in comparison with the natural solar radiation recorded in open field. The photoluminescent films RED, BLUE and RED-BLUE have the capacity to absorb UV radiation in order to re-emit it in the wavelength of red radiation,blue radiation and red-blue radiation, respectively.The results showed the radiometric characteristics of these innovative plastic films. The photoselective films GREEN4% and GREEN2% were characterised by a reduction of the R/FR ratio of the photon fluence rate in the red to that in the far red in comparison to the natural solar radiation.

Plastic films for protected cultivation capable of modifying the spectral distribution of the transmitted radiation can be developed with suitable radiometric characteristics in order to influence plant vegetative activity. In order to study such films, experimental tests were carried out at the experimental farm of the University of Bari in Valenzano (Bari, Italy), at latitude 41° 05' N, from December 2006 to September 2007. Two photoselective films (GREEN4% and GREEN2%), three photoluminescent films (RED,BLUE and REDBLUE) and one low density polyethylene film were used as greenhouse coverings for cherry trees and peach trees. The photoselective films GREEN4% and GREEN2% alter the quality of solar radiation passing through the covering materials modifying the spectral distribution of the solar radiation in the wavelength range of the red radiation (R, 650- 670 nm) and of the farred radiation (FR, 720- 740 nm) in comparison with the natural solar radiation recorded in open field. The photoluminescent films RED, BLUE and REDBLUE have the capacity to absorb UV radiation in order to retransmit it in the wavelength of red radiation, blue radiation and redblue radiation, respectively.The results showed the radiometric characteristics of these innovative plastic films. The photoselective films GREEN4% and GREEN2% were characterised by a reduction of the R/FR ratio of the photon fluence rate in the red to that in the farred in comparison to the natural solar radiation.

Film plastici utilizzati per la protezione delle colture in grado di influenzare la distribuzione spettrale della radiazione solare che li attraversa con opportune caratteristiche radiometriche sono stati recentemente sviluppati per condizionare la crescita delle piante. Allo scopo di valutare gli effetti di tali film sono state condotte, da dicembre 2006 a settembre 2007, prove sperimentali in ambiente protetto su alberi di pesco e ciliegio presso il centro sperimentale dell’Università di Bari utilizzando due film sperimentali fotoselettivi (GREEN4% e GREEN2%), tre film sperimentali fotoluminescenti (RED, BLUE e REDBLUE) e, per confronto, un film standard in polietilene a bassa densità. I filmfotoselettivi GREEN4% e GREEN2% filtrano particolari lunghezze d’onda della radiazione solare, cioè variano la distribuzione spettrale della radiazione solare nel rosso e nel rosso lontano rispetto alla radiazione solare in pieno campo. I film fotoluminescenti Red, Blue e RedBlue hanno la capacità di assorbire le radiazioni solari incidenti nell’ultravioletto per riemetterle in corrispondenza delle lunghezze d’onda rispettivamente della radiazione rossa, blu e della combinazione di entrambe. I risultati presentati riguardano la caratterizzazione radiometrica dei film plastici innovativi. I film fotoselettivi Green4% e Green2% hanno mostrato un’elevata capacità di ridurre il rapporto R/FR tra radiazione presente nel rosso (R: 650- 670 nm) e nel rosso lontano (FR: 720- 740 nm) rispetto al valore calcolato in presenza di radiazione solare naturale.