• Fragaria × ananassa
• light conversion film
• Rubus fruticosus L.
• solar light modulation
• Vaccinium corymbosum L.

The optimization of solar radiation is a new strategy to enhance plant productivity and facilitate plant acclimation to enrich light conditions compared to natural sunlight. The spectral characteristics of solar light play a significant role in plant development; however, plant responses to light quality are not uniform and can vary by species. Physiological parameters, such as photosynthetic capacity determined by CO2 assimilation and PSII photochemical efficiency, serve as key indicators of plant status and response to transmitted light. Additionally, the naturally derived antioxidants and nutraceuticals found in fruits are also light-dependent attributes influencing the functionality of edible fruit.
Light Cascade® company (LC®) specializes in research and development of light conversion formulations, have designed light downconversion films (Red, Pink, and Blue) made from polyethylene covering material with optical performances. LC® films can effectively modulate light wavebands in on-field growing conditions by converting less-utilized light into more beneficial wavelengths, thereby enhancing photosynthesis and agricultural productivity. The Red film converts green light into red light, while the Pink film shifts green light and ultraviolet (UV) light into red and blue lights, respectively. The Blue film primarily converts UV light into blue light. This thesis explores the effects of light downconversion films (Red, Pink, and Blue) on the physiological characteristics of Fragaria × ananassa cv. “Aromas,” Rubus fruticosus L. var. “Loch Ness,” and Vaccinium corymbosum L. var. “Duke,” as well as the accumulation of bioactive compounds in the fruit. The evaluation of the effects of LC® films was conducted throughout several plant phenological stages in comparison with plants grown under transparent polyethylene film.
Fragaria × ananassa plants grown under LC® films showed an increased biomass, with Blue film inducing positive results in leaf area and leaf thickness. During the flowering stage, plants grown under the Blue film demonstrated a significantly elevated net photosynthetic rate. The Blue film improved the total phenolic and flavonoid contents in fruits, with an increase in targeted phenolic compounds such as quercetin, ellagic acid, and procyanidins.
Similarly, Rubus fruticosus L. plants subjected to the Red and Blue films showed enhanced net photosynthetic rates alongside improved stomatal conductance. Both films significantly contributed to increased blackberry fruit yield, with the Red film promoting greater fruit number and the Blue film enhancing single fruit weight. No significant influence on the nutraceutical quality of the blackberry fruits were observed.

The Red film was associated with a significant increase in plant biomass of Vaccinium corymbosum L. plants, mainly new shoots and leaves, thus improving plant capacity to produce flowers in the subsequent year. Additionally, leaf thickness marked in plants grown under the Blue film was associated with the increase in palisade parenchyma portion. The highest fruit yield was recorded in plants cultivated under the Blue film, whereas the single fruit weight was significantly higher in those grown under the Red film. The Blue film additionally induced favorable organoleptic properties and enhanced antioxidant capacity, while the Pink film resulted in increased total phenolic content in blueberry fruits. In general, our findings indicated that fruits cultivated under the Blue film were able to maintain their organoleptic and nutraceutical properties when stored in cold conditions as ready-to-eat products.
In summary, this thesis explores the application of light conversion technology in berries cultivation. The findings underscore the role of solar spectrum modulation in enhancing the physiological functions, growth, and metabolism of plants. Finally, the implementation of light conversion films designed with specific wavelengths as covering material can influence key fruit parameters that are vital for fruit economic value and marketability.