Influence of growth retardant Regalis on blackberry fruit quality

Abstract

In the group of berry species, blackberry is, by economic importance for Republic of Serbia, immediately behind raspberry and strawberry. As a consequence of the hyper- production on one side and the uncertain sales prospects on the other side, the average blackberry production in Serbia has declined in recent years to approximately 12,000 t (spread to app. 15,000 individual farms). The blackberry orchards in Serbia are dominated by the Čačanska Bestrna and Thornfree cultivars, with more than 95% share, followed by the Black Satin, Dirksen Thornless and some more recent cultivars, such as Loch Ness, Chester Thornless, Triple Crown. The intensification of the cultivation technology accompanied by the introduction of the application growth retardant resulted in increasing the share of quality fruits, i.e. reducing vigour of bush. The paper presents results of a two-year study (2018–2019) into the impact of foliar application Regalis (growth retardant) on morphometric and chemical properties of blackberry fruit. It was observed that most of the tested parameters were affected by foliar application of retardant during the research, as well as by their interaction. In terms of the morphometric properties, weight (10.89 g), height (34.14 mm), and width (26.90 mm) were higher in treatment with Regalis than treatment without application. All chemical properties tested, soluble solids (9.95%), total sugars (4.98%), inverted sugars (4.71%) content, except sucrose and total acids content had higher values in the same treatment. In addition to this, the foliar application of Regalis had a positive effect on the content of secondary metabolities (total anthocianins-67.11 mg/100 g FW; total phenols-636.06 mg/100 g FW), and antioxidant capacity of fruit (2.53mmol Trolox/100 g FW).