Epsilon Open Archive

Abstract

Vaccinium myrtillus, a small dwarf-shrub native to northern Europe has received much attention during recent decades because of its economic value and as a result of the health promoting substances found in the fruits. The work outlined in this thesis focused on the effects of exogenous factors such as temperature, light and nutrient availability on the concentration of anthocyanidins in the fruits. The research also examined whether the biosynthesis of anthocyanidins in V. myrtillus fruits (bilberries) is mainly under genetic or environmental control. This information is intended to be used in developing the cultivation of the species. The concentration of anthocyanidins in bilberries was found to be sensitive to changes in temperature and day length, with higher concentrations in fruits exposed to high mean temperatures (16°C) compared to low mean temperatures (11°C) and under long day (24 h) compared to short day (12 h) conditions. However, anthocyanidin concentrations were higher in the fruits of plants growing under a closed forest canopy compared to those in direct sunlight, certain years. Anthocyanidin concentrations were also found to be positively correlated with thermal sum (after first of May each year) up to 1350 degrees (C); above this value, concentrations decreased. Even though anthocyanidin concentrations in bilberries were affected by climatic factors, the results obtained clearly show that anthocyanidin biosynthesis in bilberries is primarily under genetic control. Clones of plants originating from different latitudes differed in anthocyanidin concentration even when they were grown under the same climatic conditions and at the same latitude for a period of more than ten years. Higher anthocyanidin concentrations were found in fruits from clones with a more northerly origin compared to those from further south. The same pattern was found in wild populations. The results gathered during the work underlying this thesis indicate that with selection of suitable genotypes and with controlled growth environment, the anthocyandin concentration in bilberries could be greatly enhanced compared to natural levels and concentrations could probably be stabilized thus reducing variation between years. In combination with the strong market for bilberries there are good prospects for future cultivation of V. myrtillus.