RESUMO
The aim of this study was to examine the influence of shoot age on the biological and chemical properties of 13 black currant cultivars with different origins and ripening times. Phenological observations together with examined pomological and chemical characteristics were studied in two consecutive years at the experimental field near Belgrade, Serbia. The total content of phenols was estimated spectrophotometrically by the Folin-Ciocalteu method, while quantitative analysis of anthocyanin and flavonols aglycones was performed using a high-performance liquid chromatographic (HPLC) method. Principal component analysis was performed to establish differences in biological and chemical properties of black currants. Three-year-old shoots had an earlier start of all examined phenological stages, better generative potential, higher yields, while clusters and berries from 2-year-old shoots had significantly higher values for physical properties, total phenols, anthocyanin and flavanols aglycones and antiradical capacity. Late ripening cultivars had higher contents of all chemical compounds. The berries on 2-year-old shoots had total phenolics that ranged between 123.0 ('Titania') and 298.3 mg/100 g fresh weight (FW) ('Ometa'), while total anthocyanins ranged between 398.5 ('Ojebyn') and 1160.8 mg/kg FW ('Ometa'). According to the obtained results, cultivars 'Ometa', 'Ben Lomond', 'Tsema' and 'Malling Juel' can be recommended as the most promising for growing in the continental climate because they stood out with higher generative potential and yield, physical traits of cluster and berry, higher level of primary and secondary metabolites and DPPH activity in their berries.
RESUMO
BACKGROUND: Changes of environmental factors, created under the influence of various shading nets, could significantly affect the biological characteristics of plants grown in such conditions as well as biosynthesis of primary metabolites and ascorbic acid. Five blackcurrant cultivars - 'Ben Sarek', 'Ben Nevis', 'Ben Lomond', 'Ometa' and 'Cacanska Crna' - were cultivated in the shade of two green polyethylene nets and exposed to direct sunlight during two experimental seasons. RESULTS: In the control treatment, all cultivars contained the highest amounts of soluble solid content and number of flower buds per shoot in both years of cultivation. The bushes exposed to direct sunlight had the highest sunburn damage to the berries and leaves, and loss of yield. The greatest yield loss caused by berry damage in the present study during the experimental period was in cultivar 'Ben Sarek': 9.0% in 2010 and 15.4% in 2011. Growing in the shade of light-green net contributed the highest content of ascorbic acid. Control bushes and those shaded by light-green net had significantly higher radical scavenging activity, with values between 1.15 and 1.22 mg mL(-1). CONCLUSION: Plants shaded by nets in both years of cultivation had lower damage to leaves and berries and percentage of loss of yield, and usage of the net would be economically advantageous to growers. Fruit of blackcurrant cultivars grown in shading conditions still represent a good source of valuable nutritive and biologically active compounds.
