Browsing by Subject "Vaccinium"

Phytoplasmas are plant pathogenic phloem colonizing bacteria-like organisms. They can cause severe growth disorders in plants and thus weaken the productivity of crop plants or even kill them. Phytoplasmas have not caused any epidemics on crop plants in Finland and thus they have been little studied. The aim of this study was to find out if plants that have phytoplasma-like symptoms are actually infected by phytoplasmas. Plants with growth disorders were collected and their DNA was extracted. Phytoplasmal DNA was multiplied from the samples using PCR with phytoplasma-specific primers P1 and P7. The products were sequenced and compared with sequences available from databases. Phylogenetic trees were constructed to show the kinship between the phytoplasmas. In this thesis X-disease phytoplasmas were found from dandelion (Taraxacum spp. Weber), scentless mayweed (Tripleurospermun inodorum Schultz Bip.), creeping thistle (Cirsium arvense L.), alsike clover (Trifolium hybridum L.) and blueberry (Vaccinium myrtillus L.). Aster yellows phytoplasma was found from one red clover (Trifolium pratense L.). Data on phytoplasmas has not been published in other Nordic countries. In Lithuania phytoplasmas have been detected in several plant species such as raspberry (Rubus idaeus L.), sour cherry (Prunus cerasus L.), apple (Malus sp. Mill.), barley (Hordeum vulgare L.), oat (Avena sativa L.) and several other grasses that also grow in Finland. The climate change can increase the amount of vector insects in Finland, which will most likely help phytoplasmas spread more efficiently and cause diseases also on crop plants. The import of plants from other countries may enable the spread of new vector and phytoplasma species in Finland.

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.