The Impact of Bioregulators and Biostimulator on the Fruit Quality of Sweet and Sour Cherries

Bioregulators and biostimulators play a significant role in enhancing fruit set, weight and firmness in different tree fruit species. The aim of this study was to examine the effects of the products based on gibberellic acid (GA), 6-benzyladenine (BA), and α-naphthaleneacetic acid (NAA) on fruit set and fruit quality in the sweet and sour cherry cultivars ʻSkeena’ and ʻÉrdi Bötermö’. For sweet cherries, the treatments involved ʻOroGibbʼ (GA3 1.6 % + BA 1.6 % + B) and ʻGranPeraʼ (GA3 2% + P, K), at concentrations of 10 mg l-1 and 20 mg l-1 active ingredient (a.i.), applied at the flowering fading (BBCH 67) or when the fruit reached 60% of final size (BBCH 76). The following treatments were established: I (ʻOroGibbʼ at 10 mg l-1 a.i., applied at BBCH 67 stage); II (ʻOroGibbʼ at 20 mg l-1 a.i., applied at BBCH 67 stage); III (ʻGranPeraʼ at 10 mg l-1 a.i., applied at BBCH 67 stage); IV (ʻGranPeraʼ at 10 mg l-1 a.i., applied two times at BBCH 76 stage); V (ʻGranPeraʼ at 20 mg l-1 a.i., applied at BBCH 67 stage); VI (ʻGranPeraʼ at 20 mg l-1 a.i., applied two times at BBCH 76 stage). In addition to ʻOroGibbʼ and ʻGranPeraʼ, ʻFrutaFijaʼ (amino acids 4.5%; P2O5 13%; K2O 18%; B 0,5%; Fe 0.04%; Cu 0.01%) biostimulator was also used for sour cherry. The applied concentrations were 10 mg l-1 and 20 mg l-1 a.i., and time of application was at the end of flowering (BBCH 69) or/and when the fruit reached 60% of final size (BBCH 76). The following treatments were established: I (ʻOroGibbʼ at 10 mg l-1 a.i., applied at BBCH 69 and BBCH 76 stages); II (ʻOroGibbʼ at 20 mg l-1 a.i., applied at BBCH 69 and BBCH 76 stages); III (ʻGranPeraʼ at 10 mg l-1 a.i., applied at BBCH 69 and BBCH 76 stages); IV (ʻGranPeraʼ at 20 mg l-1 a.i., applied at BBCH 69 and BBCH 76 stages); V (ʻFrutaFijaʼ at 20 mg l-1 a.i., applied at BBCH 69 stage). Untreated trees of both fruit species were used as control. The highest fruit weight (11.6 g) and diameter (29.0 mm) of ʻSkeenaʼ were recorded in treatment VI. Applied treatments had no impact on fruit firmness, soluble solids content and acidity of ʻSkeenaʼ fruts. The highest fruit set of sour cherry cultivar ʻÉrdi Bötermö’ was recorded in the treatment I (27.4%), but only this treatment showed no significantly higher fruit weight and diameter compared to the control. Sour cherry fruits from treatment III exhibited significantly higher fruit firmness compared to the control, while the fruits from treatments I, II and III were characterized by a higher content of soluble solids and total acids.