Browsing by Subject "marjanlaatu"

The global demand for berries has grown recently, which is why the berry plants are now being cultivated in the greenhouse during the winter. In Finland, availability of natural light in the winter season is limited, and the light conditions in greenhouses are typically improved with HPS lights, but their spectrum is limited in blue light which is required by plants. LEDs are the first energy-efficient light source that enables the spectrum to be optimized to match the wavelengths absorbed by plant photoreceptors. This study compared the effect of two different light treatments on the primocane raspberry plant (Rubus idaeus L. 'Shani') in winter season. The aim was to study how blue and red LED light in addition to HPS light affect the growth, morphology, yield and berry quality of primocanes in greenhouse conditions during winter in Finland. The experiment was carried out at the University of Helsinki's greenhouses in Viikki between August 2018 and February 2019. In the vegetative stage, amount of vegetative growth, flavonoid, anthocyanin, chlorophyll content and leaf photosynthesis were measured. In the generative stage, the timing of harvest, the number of inflorescences, yield, and the berry quality (soluble solids, titratable acids, total phenolic and anthocyanin content) were measured. Increasing blue and red light in the spectrum (HPS+LED) affected both the vegetative growth and the berry quality compared to HPS light alone. Differences were observed in leaf temperature, photosynthetic activity, leaf chlorophyll and flavonoid content, growth of lateral shoots and berry anthocyanin content. In the vegetative growth phase, the HPS+LED light, contrary to the hypothesis, did not reduce the length of the main shoot, but on the other hand strongly reduced the length of the lateral shoots. HPS+LED light increased the flavonoid and anthocyanin concentration in leaves and berries, respectively, while the anthocyanin concentration in leaves and the total phenolic concentration in berries were not affected. The total yield was less than one kilogram per plant, and not affected by the light treatment. From an economic point of view the marketable yield, along with the berry quality are the key factors when producing raspberries indoor in winter because the plants were grown in completely controlled environment with additional energy. Ultimately, different wavelengths seem to interact, and their mutual relationships change the already known effects of a single wavelength.