Hedi Kaldmäe

Development of the Northern European Ribes core collection based on a microsatellite (SSR) marker diversity analysis

The purpose of the study was to support the selection process of the most valuable currant and gooseberry accessions cultivated in Northern Europe, in order to establish a decentralized core collection and, following the selection, to ensure sufficient genetic diversity in the selected collection. Molecular analyses of the material from nine project partners were run at seven different laboratories. The results were first analysed for each partner separately, and then combined to ensure sufficient genetic diversity in the core collection.

Influence of Pollination Conditions on Fruit Set of Selected Blackcurrant Genotypes and Recently Released Cultivars

Fruit set of blackcurrant (Ribes nigrum L.) cultivars ‘Almo’, ‘ Ats’, ‘ Elo’, and ‘ Karri’ and four breeders selections was investigated under open pollination, artificial, and natural self-pollination conditions in 2006–2007. The percentage of fertilized flowers, number of seeds per fruit, and fruit weight was largely genotype dependant, but it was also affected by the pollination conditions. All genotypes proved to be self-fertile, but the best fruit set occurred under open pollination conditions. There was a medium strength positive correlation between fertilization rate and fruit weight, and a below average positive correlation between the number of seeds and fruit weight.

Genotype and climate conditions influence the drop off of flowers and premature berries of blackcurrant (Ribes nigrum L.)

Abstract The aim of the present research was to study the extent of the drop off of blackcurrant flowers and young berries in the conditions of northern Europe, depending on particular genotypes and weather conditions. The study was carried out in southern Estonia in 2004–2007. The experiment involved nine recently selected genotypes from the blackcurrant breeding program of the Estonian University of Life Sciences Institute of Agricultural and Environmental Sciences Polli Horticultural Research Centre and 10 parent genotypes. Drop off is considerably influenced by the weather conditions during flowering (temperature, precipitation) and the particular genotype. Drop off is lower in genotypes ‘Ats’, 6-90-5, 1-90-15 and ‘Pilenai’, whereas it is high in genotypes ‘Zagadka’ and ‘Karri’. There is an average positive correlation between the cluster length, the number of flower buds in cluster and the extent of drop off. A strong negative correlation was found between the intra-flower fertilization ability of the genotype and drop off. There may be specimens with both similar as well as a very different extent of drop off among the genotypes originating from the same crossing combination. Drop off was lower among the genotypes where cultivar ‘Öjebyn’ was one of the parents.

Antibacterial and antioxidative properties of different parts of garden rhubarb, black currant, chokeberry and blue honeysuckle: Antibacterial and antioxidative properties of different parts of garden rhubarb, black currant, chokeberry and blue honeysuckle

BACKGROUND It is important to find plant materials that can inhibit the growth of Listeria monocytogenes and other food-spoiling bacteria both in vitro and in situ. The aim of the study was to compare antibacterial and antioxidative activity of selected plant-ethanol infusions: leaves and berries of blackcurrant (Ribes nigrum L.), berries of chokeberry (Aronia melanocarpa (Michx.) Elliott) and blue honeysuckle (Lonicera caerulea L. var. edulis); petioles and dark and light roots of garden rhubarb (Rheum rhaponticum L.) for potential use in food matrices as antibacterial and antioxidative additives. RESULTS The strongest bacterial growth inhibition was observed in 96% ethanol infusions of the dark roots of rhubarbs. In 96% ethanol, nine out of ten studied plant infusions had antibacterial effect against L. monocytogenes, but in 20% ethanol only the infusions of dark rhubarb roots had a similar effect. Chokeberry and other berries had the highest antioxidative activity, both in 20% and 96% ethanol infusions. CONCLUSION The combination of dark rhubarb roots or petioles and berries of black chokeberry, blackcurrant or some other anthocyanin-rich berries would have potential as both antibacterial and antioxidative additives in food.

Qualitative Properties of the Fruits of Blackcurrant Ribes Nigrum L. Genotypes in Conventional and Organic Cultivation

Abstract The aim of the investigation was to evaluate the effect of genotype and growing conditions on blackcurrant fruit weight and biochemical composition. The trial was carried out during the years 2011 and 2012 in South Estonia with two cultivation methods (conventional and organic) and eight genotypes of different genetic background, including two Scottish, ‘Ben Alder’ and ‘Ben Lomond’; two Swedish ‘Intercontinental’ and ‘Titania’; a Belarusian ‘Pamyati Vavilova’, and three recently selected genotypes from the Estonian blackcurrant breeding programme, ‘Karri’, ‘Asker’, and ‘Mairi’. From each genotype and in both cultivation sites 500 g of fruit at full maturity was collected in three replications. Fruit weight, soluble solids (SS), sugars, organic acids, sugar/acid ratio, and ascorbic acid (AsA) concentrations were determined. Fruits from the organic cultivation site were smaller and contained more SS and sugars, they also had a higher sugar/acid ratio than conventionally grown berries. Organic acids and AsA concentrations were higher in berries from conventional cultivation systems compared to the organic ones. ’Karri’ had the highest SS and sugar concentrations and sugar/acid ratio and the lowest concentration of acids on average over the years and cultivation methods. The highest AsA concentration was determined in ‘Asker’ and ‘Ben Lomond’.

Damage by the raspberry beetle (Byturus tomentosus De Geer) in different raspberry cultivars

Growing cultivars less susceptible to raspberry beetles (Byturus tomentosus De Geer) reduces the need for chemical control and therefore has a great impact on environmentally friendly raspberry production. To determine the susceptibility of raspberry cultivars to raspberry beetles, larvae-induced damage to raspberry cultivars from the collection of the Polli Horticultural Research Centre of the Estonian University of Life Sciences, Estonia was determined during the years 2003–2011. A total of 17 cultivars were assessed: Aita, Alvi, Herbert, Ivars, Novokitaivska, Preussen, Tomo, Algonquine, Ottawa, Haida, Helkal, Glen Ample, Glen Magna, Glen Rosa, Nagrada, Norna and Veten. The early-flowering cultivars were significantly more damaged than the late-flowering cultivars. The most damaged cultivars were Ivars and Novokitaivska. The lowest damage occurred in the late-flowering cultivars Glen Ample and Glen Magna. Late-flowering cultivars are phenologically more isolated from the raspberry beetle. Growing late-flowering and less-susceptible cultivars is a promising alternative to minimise raspberry beetle-induced damage in integrated pest management and organic farming systems.