Evaluation of the biological-economic and biochemical traits of promising Ribes nigrum hybrids in Estonia.

The evaluation of promising hybrids of blackcurrant (Ribes nigrum L.) was carried out in 2016--2018 in South- Estonia at Polli Horticultural Research Centre of the Estonian University of Life Sciences. The objective of the Estonian blackcurrant breeding programme is to produce cultivars that are winter hardy, resistant to gall mite (Cecidophyopsis ribis Westw.) and gooseberry mildew (Sphaerotheca mors-uvae (Schw.) Berk.), well suited to machine harvesting, with good yield and quality of fruits. The evaluation plot was established in the autumn of 2014. Twenty-four blackcurrant promising hybrids from the Estonian blackcurrant breeding programme and a new Estonian cultivar 'Mairi' as the standard were evaluated for beginning of flowering and fruit ripening (expressed in growing degree-days, GDD), winter hardiness, resistance to diseases and pests (expressed in scores 1--9), number of fruits per cluster, yield (kg per bush), weight of fruit and content of the soluble solids (°Brix). Fruits were analysed for titratable acids, ascorbic acid, anthocyanins and polyphenols. The evaluation revealed the best black-fruited genotypes to be Nos 3-08-1 ('Ben Alder' x 'Titania'), 7-08-1, 7-08-2 ('Intercontinental' x 'Pamyat Vavilova') and 15-09-1 ('Asker' free pollination), and the green-fruited genotype No. 8-09-3 ('Öjebyn' x 'Mairi'). All these genotypes are winter hardy and visually resistant to gall mite and gooseberry mildew. The first four produced good yields and large fruits. [ABSTRACT FROM AUTHOR]