Some Asian pear cultivars, if cultivated in regions where less chilling hours are accumulated during winter, may present uneven budding and blooming and hence, need to have their dormancy broken by artificial means. In order to minimize such problem, an experiment was conducted in a 4-year-old 'Hosui' pear (Pyrus pyrifolia) with 4.0 x 4.0m tree spacing orchard, at the Canguiri Station, in Pinhais-PR (latitude 25º25'S, longitude 49º08' and altitude of 920m), pertaining to the Federal University of Parana, in which accumulation of 141 chilling hours under 7.2ºC was reached during the 2005 winter. Treatments were applied when plants were at the A1 phenological stage (bud swelling), using a completely randomized factorial design with 4 replications in a 2x4x7 factorial scheme in which two types of tree training, vase or central leader, three mineral oil concentrations, 4, 6 or 8%, and a control applied from August to November 2005, and seven weekly performed evaluations based on the number of buds at pre-budding stage as well as broken and dead buds in four previously selected horizontally inclined 1-year-old stems per tree were tested. Obtained results showed that application of mineral oil at 4, 6 and 8% anticipated bud break compared to the control and enhanced bud break percentage in both training systems, being the concentrations of 6% and 8% more effective in anticipating bud break than 4%. The percentage of bud break at the 84th day after mineral oil application did not differ between the two training systems, i.e. vase and central leader.
Pyrus pyrifolia; chilling hours; shoot inducers; organic production; training systems
