J. Milivojević¹, D. Radivojevic¹, J. Dragišić Maksimović², R. Veberic³ and M. Mikulic-Petkovsek^3
1 University of Belgrade, Faculty of Agriculture, Belgrade, Republic of Serbia ² University of Belgrade, Institute for Multidisciplinary Research, Belgrade, Republic of Serbia ³ University of Ljubljana, Biotechnical Faculty, Department of Agronomy, Ljubljana, Slovenia

SUMMARY Two semi-erect blackberry cultivars, ‘Loch Ness’ and ‘Triple Crown’, were used to investigate the effect of Prohexadione-Ca (ProCa) on vegetative growth, generative potential and fruit quality parameters. ProCa reduced the cane and internode length, but increased the node number per meter of cane length in both cultivars. ProCa application enhanced the number of fruiting branches and yield per bush in the following year. Fruit weight, number of drupelets per fruit, fruit shape index, content of soluble solids, shikimic acid and some phenolics were significantly increased by ProCa. ProCa-cultivar interaction was significant regarding the content of quercetin-3-rutinoside and procyanidin trimer. ‘Loch Ness’ had approximately 40% higher yields per bush and contained abundant quantities of anthocyanins and flavonols, whereas larger fruits and higher content of primary metabolites, some flavanols and total hydroxycinnamic acid derivatives were found in ‘Triple Crown’. According to obtained results, the ProCa application at the rate from 100 to 200 mg L-1 is able to establish acceptable growth control without negative effects on yield and chemical fruit composition. Keywords growth retardant, fruit quality, organic acids, phenolic compounds, productivity, Rubus Watson, sugars, vegetative potential

Significance of this study What is already known on this subject? Prohexadione-Ca (ProCa) is applied to agronomic and horticultural crops to reduce unwanted longitudinal shoot growth without lowering productivity. What are the new findings? The application of this compound is able to establish growth control of blackberries without negative effects on yield and fruit quality. What is the expected impact on horticulture? Modification of vegetative primocane growth during the first season, aiming at increased quantity and quality of fruits in the next season.

E-mail: draxy@imsi.bg.ac.rs  

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Received: 31 January 2017 | Accepted: 16 May 2017 | Published: 22 August 2017 | Available online: 22 August 2017