Breaking Dormancy of “Tupy” Blackberry in Subtropical Conditions

Abstract

In subtropical or tropical conditions, the insufficient winter chill accumulation is often a limiting factor to break the dormancy of temperate-climate species such as the blackberry, which requires using products to help break dormancy. This study evaluates the efficacy of compounds in breaking dormancy of blackberry and its consequent influence on phenology and crop yields. The experiment was conducted in S ? o Manuel, State of S ? o Paulo, Brazil, in the 2011/2012 production cycle. The plants used were two-year-old “Tupy” blackberry ( Rubus spp.), with 0.6 × 4.0 m spacing (4.166 plants·ha -1 ). Pruning was performed in August, followed by the application of these treatments: control (water); hydrogen cyanamide (Dormex ? ); nitrogen fertilizer (Erger ? ) and mineral oil (Assist ? ). The concentrations of each compound used were: 2.0%, 4.0%, 6.0% and 8.0%. The compounds used influenced the budding, flowering and fruit harvest stages, in addition to providing increased yields depending on the concentration used. For hydrogen cyanamide the recommended concentration is of 4.2% and 5.4% for nitrogen fertilizer; doses above these concentrations may cause phytotoxic effects. For mineral oil the dose recommended is of 8.0%.