Nutrient Uptake and Utilization and Antioxidants of Fruits in Red Raspberry (Rubus idaeus L.) Cultivar ‘Autumn Bliss’ in response to Fertilization under Extended Photoperiod

Annual-fruiting cultivars of red raspberry ( Rubus idaeus L.) complete its entire cycle of vegetative growth, flowering, and fruiting in one growing season, which has not been well studied in response to treatments of photoperiod and fertilization. In this study, micro-propagated plantlets of ‘Autumn Bliss’ were planted in a greenhouse at Dalian, Northeast China. Some were treated with fertilizers at the rate of 12 g per plant (N-P 2 O 5 -K 2 O, 14-14-14) under extended photoperiod of 17 h with PPFD of 240 μmol m -2 s -1 at dark-time (Pho.+Fert.), while others were treated with longer photoperiod (Pho.) or with the control. Compared to the control, both growth and biomass in shoot part of ‘Autumn Bliss’ were promoted by the Pho.+Fert. treatment, but foliar nutrients declined as the symptom of nutrient dilution. The Pho. treatment had no effect on either growth or nutrient uptake in leaves, resulting in the symptom of nutrient depletion compared to the Control. Soil P availability positively correlated with foliar P concentration but negatively correlated with root length. Only the Pho.+Fert. treatment resulted in the advance of fruiting by two months at July when fruits were measured to have acceptable fruit weight of about 3 g and contents of anthocyanin at ~26.4 mg cyaniding-3-glucoside equiv. 100 g -1 Fw and total phenolic content at ~17.5 mg GAE 100 g -1 Fw.