Prohexadione-Ca and young cane removal treatments control growth, productivity, and fruit quality of the Willamette raspberry

Plant growth retardants’ applications have a practical use in fruit production, generally resulting in better vegetative growth and cropping level balance. Foliar applications of the gibberellin synthesis inhibitor prohexadione-Ca (ProCa), removal of young canes, and the combination of these treatments were evaluated in the Willamette raspberry (Rubus idaeus L). The experiment consisted of 5 treatments, including 1 untreated control. ProCa was applied during the period of April–May, as a foliar spray at active ingredient concentrations of 100 ppm (first application) and 200 ppm (second application) at a 3-week interval, either in treatment with ProCa alone or in combination with young cane removal (R+ProCa). The first series of young primocanes were removed for the first time in mid-April (R and R+ProCa) and for the second time at the beginning of May (2R). Application of a growth retardant resulted in the inhibition of the cane’s growth, followed by increasing the number of nodes per meter of cane. Positive effects of ProCa and R+ProCa on the number of fruiting laterals and yields per floricane were found without negative consequences on fruit quality, except for a reduction of total acidity. All treatments increased yield per cane. Total antioxidant capacity, total phenolics, and anthocyanin contents were significantly increased using ProCa.