Browsing by Subject "Amerikankarpalo"

This study investigated the frost hardiness of cranberry (Vaccinium macrocarpon Ait.) in four cultivars (’Early Black’, ’Howes’, ’Pilgrim’ and ’Stevens’), focusing especially on the frost hardiness of roots in soilless cultivation. Plants for the study were forced in a greenhouse from cuttings of mother plants. The cuttings were rooted in pots diameter of 10 cm x 10 cm in forest peat. Plants were set to grow in the high tunnel over the growing season. Two experiments were conducted during winter 2020–2021. In the experiments, whole plants with pots were exposed to freezing treatments in a controlled freeze chamber at the temperatures of -10, -15, -20 and -30 °C. Control plants were exposed to cooling at +2 °C for an equal time. In the first experiment, plants were exposed to freezing treatment in November straight from the high tunnel. The second experiment took place in January, and plants were overwintered outside until the experiment. After the freezing treatment one upright in each plant was cut, set in a glass tube containing distilled water, and forced in the greenhouse for 14 days. The vitality of the buds, leafs and stems in the cuttings was observed with a stereomicroscope. After the freezing treatment the vegetative growth of the plants grown in pots was cut off exluding the main shoot, which was cut 5 cm above the soil surface. Thereafter plants were forced in the greenhouse over 10 weeks (the light period of 18/6 h, temperature +20 °C). The vitality of the roots was determined by measuring the amount of the new vegetative growth. All the plants tolerated -10 ° C freeze in November and -15 ° C in January, respectively without injury. Some new growth was observed in plants exposed to freezing treatments of -5 ° C below the temperature mentioned above, but frost damage occurred, and the re-growth was decreased compared to control plants. Cultivar Stevens was more tolerant than the others in both experiments conducted. It maintained its growth potential after -15 °C freezing treatment in November, and -20 °C in January respectively. Frost hardiness (LT50) of buds ranged in November from -19 °C to -27 °C. In January ’Stevens’ buds had the highest frost hardiness (LT50 =-36 °C) and ’Pilgrim’ buds had the lowest (LT50 =-27 °C). The environmental conditions throughout the whole growing season may affect frost hardiness, thus, this experiment should be repeated for verifying the results obtained. Also the potential impact of dormancy in the experiment conducted in November cannot be ignored.

The american cranberry (Vaccinium macrocarpon) is a woody perennial plant. Cranberry fruit has been studied for its many different health benefits due to the high level of human health-promoting compounds such as flavonoids and anthocyanins. The growing season is too short in Finland, and the fruits must be harvested before frost. Studies have shown that post-harvest lighting can affect the quality of fruits. Light treatment increases the anthocyanins content and red color in fruits. Lighting during storage might improve also shelf life. The aim was to find out how different light treatments affect different quality characteristics of fruits. In this thesis, the effect of three different light treatments on the accumulation of anthocyanins and phenols during 14 days following harvest in american cranberry fruits was investigated. The light treatment was APL (multispectrum), blue and red light. The control was dark treatment. In addition, the color of the fruits, the sugar content and titratable acids were measured. Light treatments increased anthocyanin content in all varieties compared to dark control. The most effective was APL treatment. The phenol content first (7 days) increased in all varieties, after which the increase continued only in Early Black and Howes varieties. There were statistically significant differences between the light treatments only for these varieties, but only 14 days after the treatments. The treatment did not have significant effect on sugar content or the titratable acids. The berries turned red in light treatments and the color intensity increased. The treatments differed significantly from the dark, but not with each other. The results of this thesis indicate that it would be possible to ripen cranberry fruits during storage. The berries could be harvested half ripe and ripened during storage using lights. There would also be a demand for domestic cranberries in the food industry, allowing imported cranberries to be replaced by a domestic alternative.